zhaw icp research report 2011

Research Report 2011

Zurich Universities of

Applied Sciences and Arts www.engineering.zhaw.ch Research & Development

r d

Beispiel einer virtuell konstruierten Mikrostruktur. Diese wirdmit Hilfe eines stochastischen Simulationsansatzes mit kon-trollierter Variation der relevanten Transportparameter wieTortuosität oder Konstriktivität erstellt. Dargestellt mit Visuali-sierung von Transport-Stromlinien.

Example of a virtual microstructure produced with a stochas-tic simulation approach with controlled variation of transportrelevant parameters as tortuosity or constrictivity togetherwith visualization of transport streamlines.

Research Report 2011 Institute of Computational Physics

Contents

Vorwort 5

Preface 7

1 Sensors, Actuators and More 91.1 Characterisation of thermally induced damages in CRFP . . . . . . . . . . . . . . . . 101.2 Beschichtungskontrolle mit thermischer Schichtprüfung . . . . . . . . . . . . . . . . 111.3 Automatic algebraic mesh generation . . . . . . . . . . . . . . . . . . . . . . . . . . 121.4 Computergestützte Karamellproduktion . . . . . . . . . . . . . . . . . . . . . . . . . 131.5 Fussgängersimulation bei hohen Personendichten . . . . . . . . . . . . . . . . . . . 14

2 Electrochemical Cells and Energy Systems 152.1 Belenos Fuel Cell Stack: Simulation and Freezing . . . . . . . . . . . . . . . . . . . 162.2 Development of membrane mechanics in micro SOFC . . . . . . . . . . . . . . . . . 172.3 Weiterentwicklung SOFC Brennstoffzellenmodul . . . . . . . . . . . . . . . . . . . . 182.4 An interdisciplinary study of electrode degradation in solid oxide fuel cells (SOFC) . 192.5 Structural Segmentation and Stochastic 3D Modeling of La0.6Sr0.4CoO3−δ-cathodes 202.6 Calibration of Hexis fuel gas-to-air flow controller . . . . . . . . . . . . . . . . . . . . 212.7 Thermogradientenprüfstand für Brennstoffzellen . . . . . . . . . . . . . . . . . . . . 22

3 Organic Electronics and Photovoltaics 233.1 Exploring and Improving Durability of Thin Film Solar Cells (DURSOL) . . . . . . . . 243.2 APOLLO - Efficient areal organic solar cells via printing . . . . . . . . . . . . . . . . 263.3 Improving amorphous silicon solar cells by model-based characterization . . . . . . 273.4 Characterizing Large Area Tandem Thin-Film PV-Modules . . . . . . . . . . . . . . . 283.5 AEVIOM - Advanced Experimentally Validated Integrated OLED Model . . . . . . . . 293.6 Integrated Multidisciplinary & Multiscale Modeling for Organic Light-Emitting Diodes

(IM3OLED) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303.7 Numerical simulation and design of extremely thin absorber solar cells . . . . . . . . 31

Appendix 33A.1 Student Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34A.2 Scientific Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34A.3 News Articles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35A.4 Book Chapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35A.5 Exhibitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35A.6 Conferences and Workshops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35A.7 Prizes and Awards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37A.8 Teaching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37A.9 Spin-off Companies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38A.10 ICP-Team . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39A.11 Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

3 ZHAW

Institute of Computational Physics Research Report 2011

ZHAW 4


Vorwort

Auf welche Energie vertrauen Sie?

«Das Vertrauen in die Kernenergie nimmt zu» titelte 2008 eine Medienmitteilung der «swissnucle-ar», Fachgruppe Kernenergie der swisselectric.1 Im Frühling 2011 hätte das Ergebnis der schweiz-weiten Telefonbefragung wahrscheinlich anders ausgesehen. Die Katastrophe von Fukushima er-schütterte auf der ganzen Welt das Vertrauen in die Beherrschbarkeit der Kernenergie.2

Setzte die Schweiz in der Vergangenheit hauptsächlich auf die beiden Eckpfeiler Wasserkraft undKernenergie, so haben Bundes- und Nationalrat mittlerweile den Ausstieg aus der Kernenergiebeschlossen.3 Um Alternativen zu entwickeln, sind neue Konzepte gefragt. Klar ist, dass es kei-ne einfache Lösung geben wird. Die Kernenergie wird nicht durch eine einzige Technologie ersetztwerden können. Anstatt dessen ist ein breiter Mix an Massnahmen in den Bereichen Effizienztech-nologie, Elektrizitätsübertragung, Energiespeicherung sowie der Bereitstellung von Elektrizität ge-fragt.4 Neben zentralen Grosskraftwerken werden auch dezentrale, auf bestimmte Anwendungenmassgeschneiderte, Lösungen eine Rolle spielen.Die Wissenschaftler des Institute of Computational Physics (ICP) beschäftigen sich schon seiteinigen Jahren mit Themen der dezentralen Energieversorgung. Dazu zählen Brennstoffzellen fürmobile und stationäre Anwendungen (Kapitel 2) sowie neue Typen von Solarzellen (Kapitel 3).Effiziente Energienutzung ist ein wichtiges Merkmal der Displays und Beleuchtungen auf Basisorganischer Halbleiter (OLEDs) in Kapitel 3.Dass wir bei aller Euphorie über die Mitgestaltung der Energiezukunft nicht die Bodenhaftung ver-lieren, verdanken wir dem starken Praxisbezug unserer Projekte – nicht nur im Energiebereich,sondern auch in anderen Anwendungsgebieten wie beispielsweise der Thermografie. Zur kontakt-losen Messung von Beschichtungen haben wir zusammen mit unserer Spin-Off-Firma WinterthurInstruments ein eigenes Gerät entwickelt, den «CoatMaster».5

An dieser Stelle möchte ich allen Mitarbeitern unseres Instituts für ihr grosses Engagement, ihreBegeisterungsfähigkeit und die tolle gegenseitige Unterstützung ganz herzlich danken.

Thomas HockerInstitutsleiter

1www.swissnuclear.ch/upload/cms/user/MM_Eckwertstudie.pdf2en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster3www.drs.ch/www/de/drs/tagesthema/272551/275400.nationalrat-beschliesst-atomausstieg.html4www.sbf.admin.ch/htm/dokumentation/publikationen/forschung/11.06.06.NFO.StandPerspektivenEnergieforschung_d.pdf5www.winterthurinstruments.com/

5 ZHAW

www.swissnuclear.ch/upload/cms/user/MM_Eckwertstudie.pdf

en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster

www.drs.ch/www/de/drs/tagesthema/272551/275400.nationalrat-beschliesst-atomausstieg.html

www.sbf.admin.ch/htm/dokumentation/publikationen/forschung/11.06.06.NFO.StandPerspektivenEnergieforschung_d.pdf

www.winterthurinstruments.com/


ZHAW 6


Preface

In what type of energy technology do you believe?

«The confidence in nuclear power is increasing» was the title of a press release by the expert group«swissnuclear» in 2008.1 In spring 2011 the outcome of this telephone survey most probably wouldhave been the opposite. The Fukushima disaster had just happened and was a shock to the wholeworld. It definitely undermined our trust in the safety and manageability of nuclear power.2

In the past Switzerland relied on hydro-electric and nuclear power as primary electricity sources.However, later in 2011, both the Swiss Federal Council and the Swiss Parliament decided to aban-don nuclear power in the long run.3 To develop alternatives new concepts and ideas are now inurgent demand. It is already clear that there is no simple solution. There won’t be a single newtechnology to substitute today’s nuclear power capacities. Instead a mix of new technologies inthe fields of energy efficiency, energy storage, and electricity transmission seems to be our bestbet.4 Large, central power stations most probably will be complemented by decentralized andcustom-made combined heat and power applications.Researchers at our Institute of Computational Physics (ICP) have already worked for many yearson solutions for decentralized energy supplies. Projects are performed on mobile and stationaryapplications of fuel cells (chapter 2) as well as on new types of solar cells (chapter 3). The efficientusage of electricity is a key feature of displays and illuminants based on organic semiconductors(OLEDs) discussed in chapter 3.Since our research has a highly practical component there is no danger in loosing grip. This is notonly true for our work on energy topics, but also for example for our thermography applications. Incollaboration with our spin-off company Winterthur Instruments, we developed the «CoatMaster»,a device for the non-destructive measurement of coating thicknesses.5

At this point I would like to thank my colleagues for their strong commitment, their enthusiasm andmutual support.

Thomas HockerHead of the institute

1www.swissnuclear.ch/upload/cms/user/MM_Eckwertstudie.pdf2en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster3www.drs.ch/www/de/drs/tagesthema/272551/275400.nationalrat-beschliesst-atomausstieg.html4www.sbf.admin.ch/htm/dokumentation/publikationen/forschung/11.06.06.NFO.StandPerspektivenEnergieforschung_d.pdf5www.winterthurinstruments.com/

7 ZHAW

www.swissnuclear.ch/upload/cms/user/MM_Eckwertstudie.pdf

en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster

www.drs.ch/www/de/drs/tagesthema/272551/275400.nationalrat-beschliesst-atomausstieg.html

www.sbf.admin.ch/htm/dokumentation/publikationen/forschung/11.06.06.NFO.StandPerspektivenEnergieforschung_d.pdf

www.winterthurinstruments.com/


ZHAW 8


Sensors, Actuators and More

9 ZHAW


1.1 Characterisation of thermally induced damages in CRFP

Contributors: M. Bonmarin, N.A. Reinke

Partners: IDP-ZHAW, IMPE-ZHAWFunding: ZHAW School of Engineering (SoE), internal fundingDuration: 2011 – 2012

The high stiffness, strength, the good fatigueproperties and low weight make carbon rein-forced fibre plates (CRFP) a material of choicefor the aeronautical industry. Nonetheless, theexposition of CRFP to high temperatures candurably affect their performance. The detectionand the characterisation of those temperature-induced damages are crucial.Involving three Institutes of the School of Engi-neering of the ZHAW (IDP, ICP and IMPE), thisproject intends to detect thermally induced dam-ages and characterise their consequences onthe performance of carbon reinforced fibres.Small variations of the thermal properties ofCRFP resulting from the exposition to high tem-perature are investigated using highly sensitiveactive thermography methods such as lock-inand pulsed thermography (see Fig. 1).

Fig. 1: Compact measurement system for lock-inthermography

The modification of the performance consecu-tive to heat exposition are characterised withthe help of analytical methods and mechanicaltests. A powerful, compact measurement sys-tem has been developed, which allows field ap-plication of lock-in thermography.

Fig. 2: Lock-in thermographic images of CRFP before(left) and after (right) exposition to high temperature(60 seconds at 300°C)

ZHAW 10


1.2 Beschichtungskontrolle mit thermischer Schichtprüfung

Contributors: N.A. Reinke

Partners: IDP-ZHAW, Winterthur Instruments GmbHFunding: Winterthur Instruments GmbHDuration: 2011 – 2012

Heutzutage trägt nahezu jedes Objekt einefunktionelle oder dekorative Beschichtung. Da-bei sind die Aufgaben dieser Beschichtung sovielfältig wie der Verwendungszweck des Ge-genstandes selbst. Die Beschichtung, bestimmtnicht nur das Aussehen, sondern beeinflusstseine mechanischen Eigenschaften und seineKorrosionsbeständigkeit.Eine kontinuierliche Kontrolle des Beschich-tungsprozesses ermöglicht eine gezielte Ein-sparung von Beschichtungsmaterial und ist da-mit sowohl von ökonomischer als auch von öko-logischer Bedeutung. Der CoatMaster der FirmaWinterthur Instruments GmbH ermöglicht dieberührungslose und zerstörungsfreie Prüfungvon Beschichtungseigenschaften wie Schichtdi-cke und thermische Eigenschaften.

Fig. 1: CoatMasterOne

Der CoatMaster basiert auf der thermischenSchichtprüfung, die an der Zürcher Hochschulefür Angewandte Wissenschaften entwickelt wur-de. Hierbei handelt es sich um eine innovati-ve Untersuchungsmethode, bei der die Ober-fläche einer Beschichtung mit einer Lichtquel-le erwärmt wird, um Rückschlüsse auf die Ei-genschaften der Beschichtung zu ziehen. Nacheiner kurzzeitigen Erwärmung um wenige GradCelsius erfolgt die Abkühlung der Oberflächedurch Wärmeleitung in tiefere Bereiche. DerVerlauf der Abkühlung hängt von den physikali-schen Eigenschaften der Beschichtung und derUnterlage ab.Die Oberflächentemperatur klingt umso schnel-ler ab, je dünner die Beschichtung ist, sofern sie

eine geringere thermische Leitfähigkeit als derUntergrund hat. Ebenso bewirkt ein schlechtesHaftungsverhalten eine Verzögerung der Ab-kühlung, weil an der Grenzfläche ein starkesTemperaturgefälle entsteht. Es kommt zu ei-nem Temperaturstau in der Beschichtung. Ausdem zeitlichen Verlauf der Oberflächentempera-tur kann also auf die Dicke und Materialeigen-schaften der Beschichtung geschlossen wer-den.

IR-Sensor

Blitzlampe

Unterlage

Beschichtungen

IR-Strahlung

impulsartiger

Wärmeeintrag

Fig. 2: Messprinzip

Der CoatMaster ermöglicht die Bestimmung vonrelativen Schichtdicken ohne Kenntnis der ther-mischen Eigenschaften der Beschichtung. Ab-solute Schichtdicken, können mittels einer Re-ferenz bestimmt werden.Zudem können Beschichtungsparameter wieDicke oder Materialeigenschaften von mehrla-gigen Schichtsystemen in Abstimmung mit derFirma Winterthur Instruments GmbH untersuchtwerden. Die Genauigkeit der Messung hängtvom thermischen Kontrast der Materialeigen-schaften der Beschichtung und des Substratsab. Für einen dunklen Pulverlack auf einem me-tallischen Substrat liegt die Reproduzierbarkeitbei 2% vom Messwert.Unsere Kunden setzen den CoatMaster für dietägliche Prüfung von Beschichtungen auf Kunst-stoff, Keramik, Metall, Holz sowie Beschichtun-gen auf Papier ein.

11 ZHAW


1.3 Automatic algebraic mesh generation

Contributors: G. Sartoris, M. Robbiani

Partners: ZHAW, ZAMP-ZHAW, NM-Numerical Modeling GmbHFunding: Gebert Ruef StiftungDuration: 2008 – 2011

The solution of a partial differential equation bythe finite-element (FE) method depends in acrucial way on a grid which corresponds to adiscretization of the underlying physical domain.Therefore, the most time-consuming part of thesolution process of a partial differential equationmay be devoted to the generation of an ade-quate grid. The task becomes even more chal-lenging when the underlying physical domain isto be dynamically varied by the user. For theFE-simulation there are two main approachesto grid generation: geometry import from CADtools, with subsequent automatic mesh genera-tion or algebraic and functional grid constructionfrom simple domains mapped and combined to-gether to form the real geometry. The simplic-ity of the first approach allows the treatment ofcomplex geometries with relatively little user in-teraction but it is counterbalanced by the factthat unnecessarily large grids are generally cre-ated. The second approach is time consuming,requires quite a bit of skill to discover appropri-ate maps but has an inherent mathematical de-scription enabling easy variations of the geome-try and a better control of the numerical error.This project aims to develop new methods foralgebraic automatic grid generation which arerelevant to practical applications, in particular todynamical grid generation. The actual practi-cal limitations of the algebraic approach shouldbe explored and new theoretical methods inves-tigated, validated and implemented in efficientalgorithms ready to be used in real engineer-ing problems. The calculus of variations pro-vides an excellent framework for the generationof structured grids by the algebraic method. Theidea is to model the essential properties of agrid through an appropriate functional such thatoptimal grid qualities lead to extremal values ofthat functional. Thus the determination of theideal grid reduces to an optimization process towhich a broad range of numerical methods ap-ply. In particular, we may again use FE methodsto find approximate solutions to these saddle-point problems. For the selection of a func-tional, there exist many reasonable choices. Inparticular, the functional can depend on first orhigher order derivatives of the deformation gra-

dient. However, in order to minimize computa-tional time, we focus on functionals dependingexclusively on first order derivatives, i.e. on themetric tensor. Functionals determining the qual-ity of the grid as smoothness, orthogonality orconformality are well known in the literature, butin practice several qualities need to be satisfiedso that one actually works with a combinationof these functionals - the relative weight of thefunctionals being prescribed by the user.During the course of the project, it was soonapparent that the major problem is the lack ofunivocity of the diffeomorphism, a property thatmust be guaranteed in order to successfully ap-ply the algebraic method for mesh generation.Mathematically just for 2D domains and somesimple shapes one can guarantee this one-to-one property, so that for the general case, wehave to work with approximations thereof. Inparticular, a viable practical solution consists inworking with functionals showing a strong singu-lar behavior when the determinant of the met-ric tensor goes to zero. Such functionals arestrongly non-linear and a dynamic homotopicapproach is required to find numerical solutions.

Fig. 1: Dynamically deformed grid due to the rotationof the inner block and continuously adapted outermesh.

ZHAW 12


1.4 Computergestützte Karamellproduktion

Contributors: R. Axthelm

Partners: Max Felchlin AGFunding: Swiss Food ResearchDuration: 2012

Fig. 1: Farbentwicklung bei Karamellschmelze

Karamell ist eine beigefarbene, feste oder cre-mige Masse, die im Wesentlichen aus ge-schmolzenem Zucker besteht. Bei etwa 135◦C beginnt Kristallzucker zu schmelzen, wobeierst bei Temperaturen um 150 ◦C das eigentli-che Karamellisieren einsetzt, bei dem sich Far-be und Geschmack verändern. Für den star-ken Bruch, sind Temperaturen von 180 bis 200◦C notwendig. Je nach Temperatur verfärbt sichder Karamell dabei goldgelb bis tiefbraun (sieheFig. 1) und entwickelt ein typisches, mehr oderweniger herbes Röstaroma. Allerdings ist nichtnur die Temperatur sondern auch die Schmelz-dauer von Bedeutung. Beginnt der Zucker zuschmelzen, dauert es nur wenige Sekunden,bis der Karamell eine dunkle Farbe annimmt- die Herstellung verlangt entsprechend stän-dige Aufmerksamkeit. Damit die Masse ansch-liessend nicht erstarrt, wird sie, wenn der ge-wünschte Bräunungsgrad erreicht ist, mit Rahmabgelöscht.Während des Karamellisierens findet eine Rei-he chemischer Prozesse statt. Kohlenhydrateverbinden sich zu verschiedenen Polymeren,von denen einige für die braune Färbung undden bitteren Geschmack verantwortlich sind.Karamell schmeckt umso herber, je dunkler ergebrannt ist. Dabei spielen bereits kleine Nuan-cen (siehe Fig. 2) eine grosse Rolle.Der Moment bei dem der Karamell abgelöschtwird ist entscheidend. Verpasst man diesen soist das Produkt nicht mehr verwertbar und dieverwendete Menge an Zucker ist verloren. Beider Firma Felchlin ist zur Abpassung des richti-gen Moments ein Mitarbeiter verantwortlich, dermit geschultem Auge den ungefähr zehn Minu-

ten andauernden Prozess überwacht.

Fig. 2: Nuancen in der Farbgebung

Die Vermutung ist, dass nicht etwa der abso-lute Farbwert des Karamells massgeblich istfür die Bestimmung des optimalen Ablöschzeit-punktes, sondern ein Moment innerhalb derzeitlichen Farbentwicklung. Wahrscheinlich, unddas gilt es in diesem Projekt herauszufinden,sind dies Geschwindigkeit und Beschleunigungdes Schmelzprozesses, was über die Farbent-wicklung gemessen werden kann.Der Schmelzprozess wird gefilmt und der mitt-lere Farbwert in Abhängigkeit der Zeit aus demVideomaterial ermittelt. Im YUV-Farbraum neh-men die Farbwerte eine charakteristische Form(siehe Fig. 3) an. Nachdem die so ermittelteKurve geeignet entrauscht wurde können weite-re Eigenschaften des Karamellisierens ermitteltund untersucht werden.

-0.14

-0.12

-0.1

-0.08

-0.06

-0.04

-0.02 0.02 0.03

0.04 0.05

0.06 0.07

0.08 0.09

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9 Y

U V

Fig. 3: Farbentwicklung von Karamell im YUV–Farbraum

Ziel des Projektes ist die Konstruktion einesHeizkessels mit eingebauter Kamera, an dieein Computer angeschlossen ist. Eine eigensfür diesen Zweck implementierte Software sollzum richtigen Zeitpunkt einen Signalton abge-ben, womit der entsprechende Mitarbeiter, zu-sätzlich zu seinem geschulten Auge, Unterstüt-zung erhält.

13 ZHAW


1.5 Fussgängersimulation bei hohen Personendichten

Contributors: R. Axthelm

Partners: ASE GmbHFunding: ICP-ZHAWDuration: 2013

Fig. 1: Duisburger Loveparade (SZeit online", 04.08.2010)

Seit dem Unglück bei der Loveparade in Duis-burg 2010 wird der Begriff Crowd-Managementim deutschen Sprachraum öffentlich verwen-det. Er beinhaltet die systematische Planungund Überwachung einer geordneten Bewegungoder Versammlung von Menschen. Zur Verbes-serung dieser Planungen könnten Simulatio-nen von Fussgängerströmen dienen. Zum einenliessen sie sich bei der räumlichen Planung vonZu– und Abgängen einsetzen und zum ande-ren zur Kontrolle wärend des Veranstaltungs-ablaufs, wobei die Simulationsergebnisse sichdann zusätzlich auf Realdaten stützten.Der Anwendungsbereich solcher Simulations-rechnungen lässt sich nicht nur auf andereGrossveranstungen wie z.B. Fussballspiele er-weitern, sondern auch auf Planungen und Kon-zeptionierungen von Gebäuden wie Bahnsteige,Bahnhofs- oder Flughafenhallen.Die Firma ASE ist spezialisiert auf videobasier-te Erfassung von Personenströmen, agenten-basierte Simulation realistischer Szenarien unddie ereignisorientierte Simulation der Auslas-tung von Serviceplätzen. Solche sogenanntenmikroskopischen Simulationen, die jeden Fuss-gänger einzeln darstellen, stossen bei hohenPersonendichten schnell an Grenzen, so dasskeine zuverlässige Analyse mehr möglich ist.Makroskopische Modellansätze versprechen insolchen Situationen bessere Rechenergebnis-se. Bis heute ist aber keine kommerzielle Lö-sung verfügbar.Der makroskopische Modellansatz von Perso-nendichten basiert zum einen darauf die Men-schenmasse als Kontinuum anzusehen undzum anderen auf drei Hypothesen die für Perso-nenbewegungen in grossen Dichten aufgestelltwerden:

1. Die Geschwindigkeit eines einzelnen Indi-viduums wird durch die benachbarten Per-sonen und das Verhalten der Menge be-stimmt.

2. Die Fussgänger haben ein gemeinsamesZiel, das sie verfolgen.

3. Die Fussgänger nähern sich auf dem di-rektesten Weg zu ihrem Ziel, wobei siegrössere Personendichten zu vermeidenversuchen.

Anhand dieser drei Hypothesen lassen sich dieBewegung und die Dichteentwicklung der Men-schenmasse als Kontinuum mit der folgendenGleichung beschreiben:

t + ∇ · ( u) = 0 ,

wobei für die Dichte und u für die vektorielleGeschwindigkeit der Personenmasse steht. DieGeschwindigkeit hängt sowohl von der Dichte,denn jeder versucht hohe Menschenansamm-lungen zu vermeiden, als auch von der Positi-on des Ziels, in der Regel der Ausgang oder dieKonzertbühne, ab. In den verschiedenen Litera-turen werden an dieser Stelle verschiedene An-sätze gemacht. Herauszufinden, welche dieserAnsätze für die zu betrachteten Situationen diebesten Ergebnisse erzielen, ist neben der nu-merischen Berechnung einer entsprechendenLösung Teil dieses Projektes. Fig. 2 zeigt einerstes Simulationsergebnis, welches zunächstnur eine einfache Variante des eigentlichen Mo-dellansatzes darstellt.

Fig. 2: Bewegungsrichtung und Dichteverteilung ineinem Raum mit Hindernissen.

ZHAW 14


Electrochemical Cells and

Energy Systems

15 ZHAW


2.1 Belenos Fuel Cell Stack: Simulation and Freezing

Contributors: B. Perucco, A. Gentsch, F. Büchi, J. Roth, J.O. Schumacher

Partners: Paul Scherrer Institut, Belenos Clean PowerFunding: Swiss Federal Office for Energy (SFOE), Belenos Clean PowerDuration: 2010 – 2014

The project aims at providing fundamentalknowledge for future fuel cell and system de-velopments. One aspect is the operation ofa proton exchange membrane fuel cell on H2

and O2 below ambient pressure. This topic isapproached by model validation and calibrationwith a numerical one-phase 2+1D model, devel-oped by the ICP, while the PSI is providing theexperimental background for validation and cal-ibration.

Fig. 1: Geometry of the 1D MEA model. The electro-chemical reactions are simulated in the catalyst lay-ers. The model accounts for the transport of oxygen,hydrogen, water vapour, dissolved water, electricalcharge, and heat.

At the ICP, the model developement is dividedinto three subtasks. One subtask addresses thedevelopment of a flow-field model that describesthe gas flow distribution within the bipolar plates.A model reduction is performed that allows tosolve a two-dimensional flow problem of thegas distribution channels instead of a full three-dimensional problem. This reduces the compu-tational time to solve the Navier-Stokes equa-tions. The generation of a discretization mesh ofthe flow-field was achieved with the multiphysicssoftware SESES. A customized 2D mesh gener-ator was built which uses NURBs (non uniformrational B-splines) to represent curved gas dis-tribution channels.The second subtask includes the develop-ment of a 1D model of the transport pro-cesses through the membrane electrode as-sembly (MEA). The transport of electrons, pro-tons, oxygen, hydrogen, water vapour, dissolvedwater, and heat through the MEA are describedby the model. The MEA model consists of the

five layers along the through-plane direction de-picted in Fig. 1. Different model versions aretested and a simulated current-voltage curvewhere pure oxygen and air is used to operatethe fuel cell is shown in Fig. 2.We implemented a numerical solution algo-rithm to solve the partial differential equationsof the 1D MEA model. This solution algorithmcan be combined with the 2D flow-field modelin SESES. The development of this combined2+1D model is adressed in the third subtask.A Galerkin Finite Element method is used todiscretize the partial differential equations ofthe model. The nonlinear system of equationsis solved by the Newton-Raphson method thatis implemented in a runtime efficient C codelibrary. For example, a single point on thecurrent-voltage curve is calculated within about40 ms depending on the discretization. In a nextstep, the C code library will be loaded in SESESin order to solve a numerical one-phase 2+1Dmodel.Furthermore, a two-phase flow model was de-veloped describing the water transport in thegas diffusion layer (GDL) and catalyst layer(CL) of a proton exchange membrane fuel cell(PEMFC). The influence of the treatment of theGDL with a hydrophobic polymer (PTFE) on thesaturation was investigated. Thereby, we stud-ied different types of boundary conditions to cor-rectly model the flux of water from the gas diffu-sion layer into the gas channel (GC).

0.0 0.5 1.0 1.5j@A�cm2

D0.0

0.2

0.4

0.6

0.8

1.0Vcell@VD

Air

Oxygen

Fig. 2: Simulated current-voltage curves of protonexchange membrane fuel cells. Operation with pureoxygen and air to operate the fuel cell was compared.The assumptions are: pressure: P = 2.6 bar for H2, P= 2.5 bar for O2, P = 0.53 bar for air, temperature: T= 74 ◦C, dewpoint: DP = 60 ◦C

ZHAW 16


2.2 Development of membrane mechanics in micro SOFC

Contributors: Y. Safa, T. Hocker

Partners: ETH-NIM, ETH-LTNT, EPFL-SAMLAB, CSEM, NTBFunding: Swiss National Science Foundation (SNSF) SinergiaDuration: 2010 – 2012

The aim of ONEBAT project is the developmentof a miniaturized Solid Oxide Fuel Cell (micro-SOFC) power source for portable electronic de-vices used in industrial and medical fields.This new type of energy converting devicebased on liquid gas has the advantage of highflexibility (geographical independence, immedi-ate charging) and an expected large increase inenergy density.The design of micro sofc built upon multi-layerceramic films may exhibit some functional prob-lems. It has a low resistance against peelingstress at the interface between different layerswhere cracks (delamination) may occur. In ad-dition, the membrane is subjected to in-planecompressive stresses, and then, it may undergoan instability transition by buckling. Both buck-ling and cracks reduce the load carrying capac-ity of the structure. Furthermore, crack prop-agation can lead to a failure mode limiting theservice life of the fuel cell. The compression inthe film can arise during the deposition processfrom uniform temperature changes, in case ofthermal expansion mismatch between the lay-ers.In the framework of thermo-mechanical re-search activities during 2011 we mention: ex-perimental tests to investigate conditions of thebuckling patterns are handled by NonmetallicInorganic Materials Group at ETH Zurich, opti-cal measurement of the curvature of membraneand advanced measurement of the buckling am-plitudes are achieved at SAMLAB Laboratoryat EPFL Lausanne. The main contribution tothis work at ICP ZHAW was focused on the nu-merical analysis and the physical modelling ofbuckling and delamination phenomena in thethin film. On the light of Rayleigh-Ritz methodwhich is implemented in the in-house Mathe-matica code the deformation of the thin film isanalyzed as superposition of buckling modes.The energy minimization concept has allowedthe justification of the buckling shape based onthe energy storage modes.A post-processing routine is developed for thecalculation of the principal stresses in order toderive yielding conditions for the post-bucklingstage according to the Mohr-Coulomb criterion.The holding of the buckling shape under heat-

ing conditions is analyzed numerically and an-alytically based on the spectrum of the Hes-sian of post-buckling energy. The input valuesfor the simulation are determined by measure-ments achieved by NIM-ETHZ and at SAMLABEPFL (cf. Figs. 1 and 2).On the other hand, a new semi-analyticalmethod for the prediction of the buckling drivendelamination phenomena is formulated and im-plemented in Mathematica. This new formula-tion leads to an innovative contribution for theprimary design of similar applications (e.g. ther-mal barrier coatings).

Fig. 1: 3D view of an 8YSZ membrane at room tem-perature taken with white light interferometry at SAM-LAB EPFL

Fig. 2: Numerical simulation corresponding to 800MPa residual compressive stress. An octopus-likepattern with branched buckling folds is obtained

17 ZHAW


2.3 Weiterentwicklung SOFC Brennstoffzellenmodul

Contributors: P. Diggelmann (IEFE), T. Hocker, Ch. Meier

Partners: Hexis AG WinterthurFunding: Swiss Federal Office of Energy (SFOE), Swiss Electric ResearchDuration: 2011 – 2013

Zur Reduktion von Material- und Montagekos-ten entschied sich die Firma Hexis AG zurNeukonstruktion ihres Brennstoffzellenmoduls(BZM). In das BZM integriert sind nebst Zell-stack und Reformer auch wärmetauschendeElemente, welche die Betriebstemperatur so-wie die Temperaturgradienten an der Zelle be-einflussen. Die thermisch-fluidische Auslegungdes neuen Designs wird vom ICP, zusammenmit dem Institut für Energiesysteme und Fluid-Engineering (IEFE), durch Modellbildung unter-stützt.In der Konzeptphase konnte durch Analyse derMassen- und Energieströme, der Charakteri-sierung der wesentlichen Systemkomponentensowie der Abbildung des BZM-internen Wär-metauschernetzwerkes ein optimierter Betrieb-spunkt identifiziert werden (Fig. 1). Dieser soll-te mit reduzierten Wärmetauscherflächen diegeforderten Betriebstemperaturen garantieren,wodurch die BZM-Konstruktion wesentlich ver-einfacht werden kann. Erste experimentelle Un-tersuchungen bestätigten die getroffenen An-nahmen.

Brennstoff-zellenmodul

BZMWärmerück-gewinnung

WRG

Gas-Luft-Verbund

GLV

Luft-Wasser Wärmetausch.

LWWT

Eigenver-brauch EV

PDC PAC

Abgas

Heizung Vor- und Rücklauf

Wärmeverluste Umgebung

Kondensat

Inverter INV

Abwärme, Rekuperierbar

Erdgas

Luft PAC,net

Aussenhülle Galileo 1000N

Fig. 1: Fliessdiagramm der Massen- und Energieströ-me

Die laufende Konstruktionsphase soll nun durchdreidimensionale, numerische Strömungssimu-lation (CFD) in Ansys CFX unterstützt wer-den. Berechnet werden das Strömungs- unddas Temperaturfeld unter Berücksichtigung vonStrahlungswärmetransport (Fig. 2).Eine primäre Anforderung an unsere Strö-mungssimulation ist eine verkürzte Berech-nungsdauer im Vergleich zu früheren CFD Mo-dellen. Eine einzelne Berechnung nahm meh-

rere Tage in Anspruch, da die Strömungskanä-le im Stack geometrisch voll aufgelöst wurden.Das neue Modell bedient sich stattdessen ei-nes von CFX angebotenen Ansatzes für Strö-mungen in porösen Medien, wodurch der Stackzu einem mehrphasigen, dafür kontinuierlichen,Berechnungsgebiet wird.Die Strömung und der Wärmetransport im Stackwurden zunächst in CFD-Simulationen einereinzelnen, geometrisch voll aufgelösten StackRepeat Unit untersucht. Effektive Wärmeleitfä-higkeiten sowie Strömungswiderstände wurdenaus dem Detailmodell extrahiert und in das Ge-samtmodell eingefügt.Durch die besagten geometrischen Vereinfa-chungen, der Reduktion der Anzahl Fluid-Solid-Interfaces sowie einer 1:1-Gittergenerierungkonnte die Berechnungsdauer bei verbesser-tem Konvergenzverhalten auf rund 2 Stundenreduziert werden. Somit können umfangreiche-re Material- und Designparameterstudien innertnützlicher Frist durchgeführt werden.

Stack

Reformer

Gaseintritt

Lufteintritt

Fig. 2: Temperaturfeld des BZM (numerische Strö-mungssimulation in Ansys CFX )

ZHAW 18


2.4 An interdisciplinary study of electrode degradation in solid

oxide fuel cells (SOFC)

Contributors: L. Holzer, T. Hocker, B. Iwanschitz, B. Muench, P. Gasser

Partners: Hexis AG Winterthur, EMPA Dübendorf, ETH-EMEZFunding: Swiss Electric Research, Swiss Federal Office of Energy (SFOE), EU-FP7Duration: 2011 – 2014

Increasing the life time represents a key issuefor a successful market entry of solid oxide fuelcell (SOFC) systems. In recent years consid-erable progress was achieved due to detailedinvestigations of the involved material compo-nents, of their chemical and structural stabilitiesand of the compatibility among those compo-nents. Of particular importance thereby is themicrostructure stability of the porous electrodes,which is the focus of this project. The studycombines microstructure analysis (i.e. electronmicroscopy, nanotomography, image analysis)with multi-physics simulations (finite elementmodeling) and with experimental investigations(variation of electrode compositions, fabricationparameters and operating conditions).Quantitative analyses of the microstructure laythe foundations of these degradation stud-ies. New analytical methodologies were de-veloped over the last years using FIB/SEM-nanotomography (see Fig. 1) and image model-ing. Based on these developments it is now pos-sible to measure the microstructure parameters,which are critical for charge and mass transport

Fig. 1: Visualization of 3D microstructure in a Ni-CGOanode based on FIB/SEM-tomography.

(i.e. tortuosity and constrictivity) and for theelectrochemical activity (i.e. surface area, in-terfaces, TPB, connectivity). By means oftime lapse tomography even the time dependentchanges of these parameters can be described(see Fig. 2).Microstructure modeling was then introduced atICP in order to study the effects of morphologi-

cal changes on the electrode performance. Thedata from microscopy is used as structural in-put for finite element modeling. In these sim-ulations, electrochemical reactions are coupledwith charge and mass transport. These multi-physics simulations allow the calculation

Fig. 2: Change of Nickel particle size (r50) duringdegradation at 850 °C in humidified hydrogen fuel.

of area specific resistances distinguishing be-tween ohmic and polarization components, asa function of the specific microstructures as ob-served by microscopy. Including the informationfrom time lapse tomography, the FE-simulationsallow for a time dependent description of theelectrode performance as a function of the cor-responding operating conditions (i.e. temper-ature, fuel composition, water vapour content,current density).These investigations are then complementedwith systematic degradation experiments thatare performed by our industrial partners (HexisAG) and by an international consortium inthe framework of an ongoing european project(SOFC life).The interdisciplinary approach opens new pos-sibilities to study degradation on a quantitativelevel and to understand the complex interplaybetween materials and fabrication parameters,operating conditions and their influence on thedegradation kinetics. The quantitative descrip-tion of the degradation kinetics also representsthe basis for systematic improvements of a newgeneration of SOFC electrodes with longer lifetime and higher efficiency.

19 ZHAW


2.5 Structural Segmentation and Stochastic 3D Modeling of

La0.6Sr0.4CoO3−δ-cathodes

Contributors: M. Neumann, L. Holzer, T. Hocker, G. Gaiselmann, V. Schmidt, M. Prestat

Partners: Ulm University, ETH-NIM, EMPA DübendorfFunding: Swiss National Science Foundation (SNSF)Duration: 2011 – 2014

In this joint project between Ulm University,EMPA Dübendorf and ZHAW Winterthur themicrostructure of La0.6Sr0.4CoO3−δ cathodes(LSC) in solid oxide fuel cells (SOFC) is in-vestigated. A parametric stochastic 3D sim-ulation model is developed by Ulm University,which is able to describe the geometry of atwo-phase microstructure. Hereby, one phaseis completely connected and consists of spher-ical particles. Microstructures with these prop-erties appear e.g. in SOFC-electrodes, that areproduced from LSC nanopowder manufacturedwith flame spray synthesis (see Prestat et al.(2010), Electrochemistry Communications 12,292-295).The stochastic model is developed to detect cor-relations between the production process (e.g.variation of sinter temperatures and/or changeof pore former contents) and the resulting mi-crostructures as well as the corresponding elec-trode performance. It is based on image dataof LSC-cathodes with different sinter tempera-tures, that is to say 750◦C, 850◦C and 950◦C,gained by high resolution FIB-SEM tomography(see Fig. 1).

Fig. 1: Left: Real data from LSC-cathode with sintertemperature 850◦C. Right: Realization of the modelwith sinter temperature 850◦C.

On the 3D-images one can see, that the LSC-phase is dominated by a dense packing ofspherical particles. This phase is representedby a union of moderately overlapping spheres

in a first step, whereas the proceeding is similarto the one for segmentation of porous electrodematerial in Li-ion batteries (see Thiedmann etal. (2011), Computational Materials Science,50, 3365-3376).Based on the sphere representation, the LSC-phase is modelled with ideas from stochasticgeometry and graph theory. The model con-sists of a random sphere system, where themidpoints are realizations of a complex 3D pointprocess. In order to assure the perfect connec-tivity of the sphere system, a modified version ofthe relative neighborhood graph is introduced,which controls the radii of the random spheres.Finally the stochastic model of the LSC-phaseis described by certain parameters, whichare fitted to three different microstructures ofLSC-cathodes, produced of sintering temper-atures 750◦C, 850◦C and 950◦C. For eachconstellation of parameters corresponding 3D-microstructures can be realized. The model isthen validated by comparing structural charac-teristics (e.g spherical contact distribution func-tion, continuous pore size distribution) from the3D-realizations and the FIB-tomographs. For allthree sinter temperatures a good fit is achieved(see Fig. 2).

Fig. 2: Comparison of the spherical contact distri-bution functions from the binarized FIB-SEM data(black) and realizations of the model for different sin-ter temperatures (blue). From left to right: 750◦C,850◦C, 950◦C.

ZHAW 20


2.6 Calibration of Hexis fuel gas-to-air flow controller

Contributors: M. Linder

Partners: Hexis AG WinterthurFunding: Hexis AG WinterthurDuration: 2010 – 2011

The Hexis fuel cell system Galileo 1000 N pro-vides the electrical energy and heat demandof single family homes from natural gas. Forfuel cell operation, an upstream gas reforma-tion is necessary to convert the natural gas,i.e. mostly methane, into hydrogen and carbon-monoxide. This conversion is realized by a cat-alytic partial oxidation (CPOx) process. Thechallenge for the CPOx-process is to accuratelycontrol the fuel-to-air ratio to avoid soot genera-tion and CPO-catalyst overheating. Both causeefficiency losses and damages to the fuel celland the reformer. The Hexis gas-to-air ratio con-troller (GARC) uses two hot film anemometers.Since this measurement principle relies on thethermo-physical properties of the respective gasmixture such as its heat capacity and its heatconductivity, unavoidable variations in the natu-ral gas composition can lead to significant flowdeviations.The aim of this work was to develop a new strat-egy for the GARC calibration and the initial oper-ating settings to avoid both soot generation andexcessive performance losses for different natu-ral gas compositions. For this purpose, severaltests with different gas compositions and flowrates were conducted. The results are shownin Fig. 1. One sees that for certain gas com-positions the deviation of the flow rate from itsset point is quite large. Based on these results,it first seemed rather unrealistic to find a practi-cable way to run the Hexis Galileo system withdifferent gas qualities.Nevertheless we started tackling the problem bylooking for a systematical relationship betweenthe observed flow deviations and the physicalproperties of the tested fuel gas compositions.Therefore different regression models and datatransformations were compared and tested. Asshown by the red marks in Fig. 2, we finallyfound appropriate correlations for the flow de-viations based on the specific heat capacity and

the heat conductivity of the fuel gas. The pur-ple marks show the correlated fuel-to-air ratio,which includes flux deviation and changes inideal fuel-to-air ratio caused by varying fuel gascompositions. To avoid soot generation we haveto ensure a positive fuel-to-air ratio. To achievethis, we applied an additional safety factor thatleads in any case to a positive deviation asshown by blue marks.The introduced approach for the GARC calibra-tion and determination of initial set point is cur-rently in use at Hexis. From the field engineersthere are not any reports about nameable inci-dents known so far.

-5

0

5

10

15

20

me

an

de

via

tio

n to

be

llow

s-t

yp

e g

as

flo

w m

ete

r / %

volumetric deviation for different gas compositions

!"#$%&'%()*%+#,# !"#$%&'%()*%+#-# !"#$%&'%()*%+#.# '/01#&1234+#

Fig. 1: Measured GARC flow deviation for differentnatural gas compostions

-10%

-5%

0%

5%

10%

15%

20%

25%

-6% -4% -2% 0% 2% 4% 6% 8%

!"#$%&'()'*)fu

el-to

-air r

atio

/

%

gas mass flux deviation / %

model based GARC behavior for different natural gas

m-flux deviation sum sum incl. λoffset

Fig. 2: Cumulated fuel gas-to-air ratio deviation fordifferent natural gas compositions

21 ZHAW


2.7 Thermogradientenprüfstand für Brennstoffzellen

Students: P. Lehnherr, D. Wild

Category: Projektarbeit, Studiengang Maschinentechnik MTMentoring: T. Hocker, L. KaufmannHanded In: Dezember 2011

Diese Projektarbeit beschäftigte sich mit demThermogradientenprüfstand der Firma Hexis.Mit dem TGP können die Brennstoffzellen desBrennstoffzellen-Heizgerätes Galileo 1000 Nauf ihr thermo-mechanisches Bruchverhaltenuntersucht werden. Ziel dieser Arbeit war es,ein überarbeitetes Design des TGP aufzubau-en und in Betrieb zu nehmen. Nach Inbetrieb-nahme sollten Prüfstand- und Zellentests durch-geführt werden. Zudem sollte eine statistischeAuswertung der Daten durchgeführt werden. Eswurde definiert, mit einem Probenumfang von30 Zellen zu arbeiten, um ein realistisches Bildder Lebensdauer der Zellen zu erhalten. Derneue Prüfstand konnte nach einigen Anpassun-gen erfolgreich in Betrieb genommen werden.Es zeigte sich, dass die aktive Kühlung mit-tels Druckluft gut funktioniert. Durch diese Küh-lung sowie durch die Reduktion der thermischenMasse konnte der Prüfzyklus gegenüber demVorgängermodell von ca. 50 min auf ca. 30 minreduziert werden. Nach ersten erfolgreichenPrüfstandtests, zeigte sich jedoch, dass mitder bestehenden Prüfstandkonstruktion nicht al-le Probleme der Vorgänger-Konstruktion beho-ben werden konnten und noch keine rationellePrüfung der Zellen durchgeführt werden kann.Während den Belastungstests der Zellen tretennach wie vor Störsignale auf, weshalb viele Zel-lentests vor Ende des Prüfvorgangs abgebro-chen wurden. Dies führte dazu, dass im Rah-men dieser Projektarbeit nur wenige auswertba-re Messresultate aufgenommen werden konn-

ten. Deshalb kann aufgrund der Auswertung derDaten mittels Weibull-Analyse keine verlässli-che Aussage über die Stabilität der Zellen ge-macht werden. Damit das Ziel einer rationellenZellenprüfung mit dem TGP erreicht wird, sindnoch weitere Verbesserungen am Prüfstand nö-tig. Für das weitere Vorgehen wird empfohlen,das Design oder die Materialwahl des Deckelszu überarbeiten um die Entstehung der Störge-räusche zu verhindern. Zudem sollte die Hei-zung im Bezug auf Isolation zum Gehäuse undder Langlebigkeit überarbeitet werden.

Fig. 1: CAD Modell des überarbeiteten Thermogradi-entenprüfstand

ZHAW 22


Organic Electronics and

Photovoltaics

23 ZHAW


3.1 Exploring and Improving Durability of Thin Film Solar Cells

(DURSOL)

Contributors: B. Ruhstaller, T. Lanz, S. Züfle, M. Neukom, M. Schmid

Partners: EMPA, EPFL, CSEM, SUPSI, ZHAW, AlcanFunding: Competence Center Energy and Mobility (CCEM-CH), Swiss Electric ResearchDuration: 2011 – 2013

The CCEM-CH project DURSOL aims at joiningthe competences of several partners in micro-morph silicon, compound semiconductors, dyesensitized and organic thin film solar cells. Theproject objectives are focussed towards the un-derstanding of fundamental degradation phe-nomena in thin film solar cells. Degradation isdue to complex mechanisms related to inher-ent material stability, interdiffusion across junc-tions, and due to external influences such asambient atmosphere and solar light, and it cer-tainly depends on the type of semiconductorsbeing used in the devices and how the solarcells are encapsulated. The task for the ICPwithin this project is to advance its numericalmodels of the various solar cell techniques be-ing investigated: the dye-sensitized solar cells(DSCs), organic photovoltaics (OPVs) and thinfilm silicon solar cells. This is done within collab-orations with experimental groups (EPFL-LPI,CSEM and EPFL-PVLab). The progress madeduring the first project year is summarized be-low:

Model-based analysis of dye-sensitized solar cell degradation

We extended our coupled optical and elec-trical model for the dye-sensitized solar cell(DSC) in such a way that several transient ex-periments can be simulated (transient photo-voltage/photocurrent decay, impedance spec-troscopy, intensity modulated photovoltage andphotocurrent spectroscopy (IMVS/IMPS)). Thisallows to compare a combined set of steadystate and transient measurements to the cor-responding simulations and to extract accuratevalues for the model parameters. This proce-dure will be applied to DSCs of different elec-trolyte composition and on aged cells at differentstages of the aging process.The electrical part of the DSC model is based onthe continuity equations for electrons in the con-duction band of the TiO2 and for triiodide andiodide species in the electrolyte. It describesthe diffusive transport of these charge carriers inthe TiO2 conduction band (electrons) and within

the pores of the nanoporous TiO2 and bulk elec-trolyte layers (triiodide and iodide). Trapping atan exponential distribution of band gap states istaken into account within the framework of thequasi-static approximation. Recombination ismodelled by a sublinear power law dependence.In addition, charge transfer at the counter elec-trode is taken into account. The whole model re-sults in a set of three coupled non-linear partialdifferential equations (PDEs), which are solvednumerically. For the simulation of small per-turbation transient experiments the system ofPDEs is expanded around the steady state solu-tions and the perturbation equations are solved.The DSC test cells are produced and measuredby EPFL-LPI. In the first step, the ICP obtained aset of measurements on three different cells withthree different dyes (C101, Z907 and N719).On these cells, IV-curves and impedance spec-tra were measured from 0.01Hz to 1MHz in thedark and under illumination. This combined setof measurements is used to extract the modelparameters by comparing the measurements tosimulated data. This is shown for a single mea-surement in the figure below.

Fig. 1: Measured (black) and simulated (blue)impedance spectrum of a DSC test cell.

Spectral reflectometry and electro-absorption in organic solar cells

The ICP has launched the development of anadvanced characterization setup for electroab-sorption and examined organic solar cells fab-

ZHAW 24


ricated at CSEM. The electroabsorption (EA)technique investigates the change in the ab-sorption spectrum of a semiconductor underthe influence of an applied electric field. Thischange can be explained by the macroscopicStark effect. Since the effect is small it can onlybe measured by a sophisticated setup, using asmall signal response and lock-in technique. Avoltage consisting of a dc and a modulated (ac)part is applied to the electrodes of the solar cell.Then the reflected or transmitted light is mea-sured by a photodiode. We use the so-calledreflection geometry as the back electrode is in-transparent. When an external dc+ac voltage isapplied, an electric field inside the organic semi-conductor is formed in addition to the built-infield. The measured signal of the photodiodeis then deconvoluted into the dc-part and theac-part on the first or second harmonic of themodulation frequency, using a phase-sensitivelock-in amplifier. Our light source combinedwith a monochromator allows us to measure thespectral electroreflectance signal in the spectralrange of 400 to 1000 nm with sufficient resolu-tion (see Fig. 2).

−2

0

2

550600650700750800850

−6

−4

−2

0

2

4

6

8

x 10−3

Vdc (V)wavelength (nm)

EA

vz

EAvz

Fig. 2: Measured EA spectrum versus DC voltage.

The ICP has a strong expertise in the model-ing of organic electronic devices both for ad-vanced characterization and device optimiza-tion. The simulation-based description of

electro-absorption measurements will allow usto better extract material parameters and con-firm results of electrical device simulations. Thedirect extraction of the built-in voltage from EAmeasurements has been shown many times byjust looking for the dc voltage at which the EAsignal vanishes. Also the electric-field profile ina multilayer organic device can be estimated.But charge injection and space-charge effectscan render this analysis quite difficult, necessi-tating a simulation approach.

Extended light scattering model forthin film silicon solar cells

Thin film solar cells based on amorphous andmicrocrystalline silicon suffer from significantaging of the active layer. Therefore one must re-sort to even thinner films. This requires the useof suitable light trapping schemes. We have ex-tended an existing scalar light scattering modelfor coherent layers and experimentally validatedit in a collaboration with the EPFL-PVLab. Thecell under consideration and the comparison ofthe spectral quantum efficiency is shown in thetwo figures below. The planar cell is comparedto the one with a structured ZnO interface. Im-proved absorption is observed for the cell witha rough ZnO interface. The simulations agreenicely with the experiment.

Fig. 3: Comparison of measured and simulated spec-tral quantum efficiency of a single-junction microcrys-talline silicon solar cell.

25 ZHAW


3.2 APOLLO - Efficient areal organic solar cells via printing

Contributors: M. Neukom, S. Züfle, T. Lanz, N.A. Reinke, B. Ruhstaller

Partners: TU/e Eindhoven (NL), University Jaume I (E), CSEM, BASFFunding: Swiss Federal Office of Energy (SFOE)Duration: 2008 – 2011

The APOLLO project with several internationalacademic and industrial partners was carriedout from 2008 to 2011. It aimed of combiningplastic electronic expertise to empower printedelectronics applications. The focus therein ison single and tandem organic solar cells com-prising newly developed donor materials. Dur-ing the project period a comprehensive devicemodel for the study and interpretation of mea-sured data has been developed at the ICP.Thus the whole process chain from light absorp-tion, exciton dissociation, charge carrier trans-port and collection by the electrodes is cov-ered. The institute’s expertise could so be ex-tended from OLED to OPV modelling. Simulta-neously our experimental capabilities have beenstrongly extended, allowing for comprehensivemeasurements joined with simulations and thusenabling a better understanding of the underly-ing physics.During the last year of the project, the CE-LIV (charge extraction by linearly increasingvoltage) method has been extensively usedin addition to the steady-state current-voltage(JV) curves. By applying various transientand steady-state measurement techniques andcomparing them to simulations it is possible tofit important material parameters like the chargecarrier mobility or injection barriers with higheraccuracy. For example, in a measurement se-ries we could ascribe different extracted mo-bility values to different morphologies. A toolto fit multiple curves of different measurementtechniques has been developed for this task.Fig. 1 shows the fitting of multiple curves withthe same set of parameters.Temperature-dependent measurements alsoconstitute a promising approach for validatingthe physical models included in the simulation.The temperature strongly influences injection aswell as transport. Therefore a systematic inves-tigation important. Fig. 2 depicts the depen-dence of the open-circuit voltage on the vari-able temperatures and illumination intensities

and shows a linear behaviour.Through this project the international collabora-tion has been strengthened and the expertise ofthe ICP in modelling organic electronic devicescould be increased and extended by experimen-tal experience.

Fig. 1: Fit of transient and steady-state measure-ments at varying illumination intensities and bias volt-ages.

Fig. 2: Temperature-dependence of the open-circuitvoltage for different illumination intensities.

ZHAW 26


3.3 Improving amorphous silicon solar cells by model-based

characterization

Contributors: T. Lanz, B. Ruhstaller

Partners: Korea Advanced Institute of TechnologyFunding: Swiss State Secretariat for Education and ResearchDuration: 2011

In recent years, thin-film solar technology hasincreased its market share thanks to improve-ments in module conversion efficiencies as wellas improved reliability. Further improvements inconversion efficiency on the solar cell level arestill possible, thus offering the potential for evenlower $/Watt prices for modules. This projectaims to improve the performance of pin typeamorphous silicon (a-Si) thin-film solar cells bymodel-based characterization and developmentof advanced processing methods for high sta-bilized efficiency. The single-junction a-Si solarcell is sophisticated enough to be industry rele-vant, yet simple enough to be scientifically ex-amined by physics-based models.

Fig. 1: Measurements of the external quantum effi-ciency (EQE) for three different types of amorphoussilicon solar cells.

Within this project we were able to improve theunderstanding of the role of thin layers of lithiumfluoride (LiF) that are used together with alu-minum as back reflectors in thin-film a-Si solarcells. Measurements of the external quantumefficiency (EQE) for three types of a-Si solarcells with and without LiF are shown in Fig. 1.LiF/Al back reflectors are commonly used in or-ganic solar cells. Recently, they were provensuitable for highly efficient a-Si pin type solarcells [Fang et al., IEEE T-ED, 58(9), 2011]. Therole of the LiF is twofold: due to its low refrac-tive index it increases the reflectivity of the backreflector and it creates a surface passivation ofthe Si/Al interface. Using our recently validatedoptical model [Lanz et al., JAP, 110(3), 2011]

we studied the influence of thin layers of LiF onthe optical intensity distribution within these so-lar cells. A visualization of the computed energyflux, denoted by the Poynting vector, within theintrinsic layer of the a-Si solar cell containing aLiF-based back reflector is shown in Fig. 2.

Fig. 2: Visualization of the computed energy flux(Poynting vector) within the intrinsic layer of the amor-phous silicon solar cell.

The use of dedicated samples, deposited on flatsubstrates, leads to pronounced interferences inthe spectral response (see Fig. 1). These inter-ferences are highly sensitive to the thicknessesof the layers as well as the reflectivities of theinterfaces. By comparing the measurement re-sults with the optical simulations we may assessthe impact of the LiF on the optical intensity dis-tribution and distinguish between gains associ-ated with the increased reflectivity of the backreflector and the influence of the LiF on the elec-trical cell characteristics. We find that, for cellson flat substrates, the increased reflectivity ofthe LiF/Al back contact accounts for a 7% in-crease in short circuit current, a gain that maybe attributed solely to the optical impact of theLiF. Our findings thus help to assess the com-mercial viability of LiF/Al back reflectors.

27 ZHAW


3.4 Characterizing Large Area Tandem Thin-Film PV-Modules

Contributors: T. Lanz, B. Ruhstaller, D. Schär, F. Baumgartner

Partners: IEFE-ZHAWFunding: ZHAW School of Engineering (SoE), internal fundingDuration: 2011 – 2012

Thin-film solar module technology has by nowreached a 20% share of the worldwide installedsolar modules. This technology still offers thepotential for substantial reductions in productioncosts, thus lowering the specific $/Watt prices.Compared to standard crystalline silicon solarcells, thin-film solar cells reach lower conversionefficiencies. Combining two different types ofsolar cells in a serial interconnection to a tan-dem solar cell allows increasing the efficiencyby about 25%, as a larger proportion of the solarspectrum can be absorbed. However, the depo-sition of such multiple layer successions with lat-erally homogeneous thicknesses over large ar-eas is challenging. Furthermore, characterizingtandem modules and determining their nominalpower requires more advanced equipment thanstandard single-junction modules and, as of to-day, there is no reliable and fast method for largenumbers of samples. Thus, the scope of thisproject is the development of a novel spectralcharacterization of tandem solar modules.

Fig. 1: Excerpt of the circuit diagram describing theinterconnection of thin-film solar cells in a solar mod-ule used in SPICE modeling.

The responsibility of ICP within the project is thedevelopment of an electro-optical model of thetandem thin-film solar module. For the opticalmodel we employ our recently validated opticallight-scattering model [Lanz et al., JAP, 110(3),2011], that was developed in collaboration withthe PVLAB of EMPL IMT-NE. For the electricalmodel we consider equivalent circuit modeling

using SPICE, see Fig. 1, as well as finite ele-ment modeling using seses. Our model takesinto account the different spectral responsesof the top and bottom solar cells, as well aslight scattering at rough interfaces, as found inall commercially viable modules. Further, themodel considers charge transport in the trans-parent electrodes over the entire module area.The model thus allows studying the overall influ-ence of lateral inhomogeneities of the depositedlayer thicknesses as well as defects such as ver-tical short circuits, see Fig. 2. We intend to val-idate the coupled model with measurements oftandem solar modules and support the develop-ment of the measurement setup to be integratedinto the Solarbus.

Fig. 2: Visualization of the calculated current densi-ties in a thin-film solar module that contains a verticalshort circuit (a pinhole).

The validated model combined with the spec-tral measurement setup shall be used to detectlateral inhomogeneities on the module level, aswell as identify and quantify quality and agingissues. Further, the model can be used to op-timize the layout of modules, such that mod-ule performance indicators become insensitiveto manufacturing tolerances.

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3.5 AEVIOM - Advanced Experimentally Validated Integrated

OLED Model

Contributors: B. Ruhstaller, B. Perruco, E. Knapp

Partners: Philips Research Aachen and Eindhoven, Technical University Dresden,University of Cambridge, University of Groningen,Eindhoven University of Technology, Sim4tec, Fluxim

Funding: EU FP7Duration: 2008 – 2011

In March 2011 the EU-funded project AEVIOM(2008-2011, www.aeviom.eu) ended. It focusedon the modeling of organic light-emitting de-vices. Fig. 1 shows the difference in form factorbetween OLEDs and conventional light sources.

!Fig. 1:OLEDs in comparison with conventional lightsources

During the last three years a “second gen-eration” OLED model which takes the conse-quences of the disordered nature of realis-tic organic semiconductor OLED materials intoaccount was realized. An advanced three-dimensional (3D) supercomputer Monte Carlocharge transport and recombination model wasdeveloped by our project partners. The3D-results were “translated” to accurate one-dimensional expressions, and using these ex-pressions fast PC-software tools were devel-oped by ZHAW and Fluxim. Intensive experi-

mental studies have been used to validate themodels developed. Experimental characteriza-tion methods such as current-voltage curves,dark injection transient current measurementsand impedance spectroscopy for OLEDs can bereproduced with the software as shown in Fig. 2.

!

Fig. 2: Frequency-dependent capacitance of differentOLEDs

It shows the frequency-dependent capacitancefor trapfree OLEDs and trap-affected ones.Further, applications of this second-generationOLED modeling tool have been demonstratedfor a complete “hybrid-white” OLED, based onexperimentally determined hole and electronmobility functions, using the world’s first full3D Monte Carlo OLED modeling as a bench-mark. The model has also been used to sup-port OLED lifetime and color stability studies.Predictive modeling has been demonstrated forsingle-layer OLEDs, and the realization of sucha demonstration is in good progress for multi-layer OLEDs.

29 ZHAW


3.6 Integrated Multidisciplinary & Multiscale Modeling for Or-

ganic Light-Emitting Diodes (IM3OLED)

Contributors: M. Loeser, E. Knapp, K. Lapagna, B. Ruhstaller

Partners: Holst Centre (Eindhoven, NL), Philips Research Laboratory (Aachen, D), Fluxim (CH),Moscow Engineering Physics Institute (MEPhI), Kintech Lab,Photochemistry Center of the Russian Academy of Sciences (PCC RAS)

Funding: FP7 of the European CommissionDuration: 2011 – 2014

The EU-funded IM3OLED project, being an in-ternational collaboration between European andRussian partners, aims at developing a softwaretoolset for multiscale OLED modeling. Such atool would help the OLED industry escape to-day’s "trial-and-error" development and acceler-ate towards the goal of 150 lumens per Watt de-vices.Overall OLED efficiency depends on manyfactors: the properties of the light emittingmolecules, deposition onto the substrate, inte-gration into a device, extracting the light from theactive layer and the device, heat managementand more. Complicating things further, many ofthese factors are interlinked. For example, howthe device heats up in operation may affect themolecule’s ability to generate light and the waylight travels through the device. This makes itextremely difficult to predict how innovations inone area will affect performance in others, lead-ing to a trial-and-error approach in R&D.IM3OLED aims to help the OLED industryspeed up development by creating new model-ing software that allows a more systematic R&D

process. This software toolset will predictivelymodel OLEDs in 3D and at all length scales –from molecular to large-area devices. It will in-clude molecular calculations, electrical and op-tical simulation, 1D-3D light extraction and scal-ing / integration effects. Importantly, the tool willincorporate a dynamic feedback loop, enablingdevelopers to accurately predict how changes inone area of OLED development affect other ar-eas. This will allow multiple OLED properties tobe optimized simultaneously.Together with its spin-off company Fluxim AG,the Institute of Computational Physics (ICP)constitutes two Swiss partners among thefour European partners funded by the Euro-pean Commission’s seventh framework pro-gram (FP7). While Fluxim commercializes sim-ulation software as an easy-to-use tool, the ICPdevelops numerical algorithms. The tasks ofthe Swiss partners are the electrical modelingof charge transport in the continuum approach,the light-outcoupling of planar and structuredOLEDs as well as the electrothermal aspects oflarge-area OLED panels.

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3.7 Numerical simulation and design of extremely thin absorber

solar cells

Contributors: M. Loeser, K. Lapagna, B. Ruhstaller

Partners: EMPA ThunFunding: Swiss Federal Office of Energy (SFOE)Duration: 2011 – 2012

This project is a joint research effort amongthe Laboratory for Mechanics of Materials andNanostructures of the EMPA Thun and the Insti-tute of Computational Physics of the Zurich Uni-versity of Applied Sciences, to investigate andimprove - both numerically and experimentally- the optical characteristics of nano-structured,extremely-thin absorber solar cells.In recent years extremely thin absorber (ETA)solar cells have received considerable attention,and despite their yet low efficiencies, rangingabout 2.5%, they are considered as promisingnovel devices for converting sunlight into elec-tric energy. The use of extremely thin absorberlayers has numerous advantages. The probabil-ity that two optically generated carriers recom-bine before they reach the contact electrodesand are thus lost for energy conversion stronglydecreases with the width of the absorber layer.In traditional photovoltaic (PV) applications thisissue was dealt with by employing very expen-sive absorber materials with excellent electroniccharacteristics. ETA solar cells do not only re-quire a strongly decreased amount of absorbermaterials but also allow for the use of absorberswith significantly poorer electronic propertiesthat come at a strongly reduced price.However, the efficiency of ETA solar cells is notonly determined by their electrical, but also bytheir optical characteristics. The ability to ef-ficiently trap and convert incident sunlight is akey feature that decides about economic suc-cess. In many cases the percentage of the inci-dent light that is converted into free charges de-pends exponentially on the absorber thickness.In order to combine the advantages inherent tothin absorbers with the necessity of high opticalabsorption efforts must be made to enlarge theoptical path in such way that the solar cell canabsorb a significant fraction of the incident sun-light. To gain deeper understanding of the un-derlying complex optical processes and to ob-tain optimal device designs numerical simula-tions of the complete three-dimensional (3-D)problem are indispensible, as ill-chosen micro-structures can even decrease the device perfor-mance.

Fig. 1: Fitting refractive index model parameters tothe measured absorption spectra for the layer struc-ture glass/FTO/ZnO.

Yet, due to the combination of large devicesand small micro-structures the accurate multi-dimensional simulation of such structures ischallenging. At the ICP we developed a 3-D simulation software that solves Maxwell’sequations at greatly reduced computational costthanks to a novel numerical method. This soft-ware allows to obtain full-wave solutions for ge-ometries that so far could not be numerically an-alyzed due to their large size.Prior to comparing the reflection and absorptionspectra obtained from spectral measurementsand three-dimensional optical simulations weensured that we employ the correct materialparameters (above all, the refractive indices).We extracted the refractive indices of the rele-vant materials (in particular from FTO and ZnO)from the measured data. The procedure of pa-rameter extraction is based on fitting absorp-tion and transmission spectra that are obtainedfrom one-dimensional transfer-matrix calcula-tions (using the software SETFOS) to the mea-sured spectra. The numerical values that wereobtained for n and k agree reasonably well withwhat is reported in literature.As the foundation for a comparison between nu-merical and experimental data has now beenlaid, we can start the benchmarking procedurewith the full-wave simulations.

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Appendix

33 ZHAW


A.1 Student Projects

• P. Lenherr, D. Wild: Thermogradientenprüfstand für Brennstoffzellen, Betreuer: L. Kaufmann,T. Hocker, Firmenpartner: Hexis AG, Winterthur (2011)

• M. König, P. Zuber: Thermische Analyse eines Schokoladen-Kühlkanals, Betreuer: T. Hocker,M. Suter, Firmenpartner: Max Felchlin AG, Schwyz (2011)

• H. Schmitt: Monte-Carlo Simulation von organischen photovoltaischen Zellen, Betreuer: N.A.Reinke, M.T. Neukom

• P. Baur, S. Ernst: Entwicklung eines LED-Screens für Werbung unter Eisflächen in Hockeya-

renas, Betreuer: N.A. Reinke, R. Ritzmann

A.2 Scientific Publications

1. S. Wenger, M. Schmid, G. Rothenberger, A. Gentsch, M. Grätzel, J.O. Schumacher: Cou-

pled optical and electronic modeling of dye-sensitized solar cells for steady state parameter

extraction, J. Phys. Chem. C, 115 (20), pp 10218-10229 (2011).

2. M. Neukom, N.A. Reinke, B. Ruhstaller: Charge extraction with linearly increasing voltage:

A numerical model for parameter extraction, Solar Energy 85, 6, 1250-1256 (2011).

3. T. Lanz, B. Ruhstaller, C. Battaglia, C. Ballif: Extended light scattering model incorporating

coherence for thin-film silicon solar cells, J. Appl. Phys. 110, 033111 (2011).

4. L. Holzer, B. Iwanschitz, T. Hocker, B. Münch, M. Prestat, D. Wiedenmann, U. Vogt, P. Holtap-pels, J. Sfeir, A. Mai, Th. Graule: Microstructure degradation of cermet anodes for solid oxide

fuel cells: Quantification of nickel grain growth in dry and in humid atmospheres, J PowerSources, 196, 12791294 (2011).

5. L. Holzer, B. Münch, B. Iwanschitz, M. Cantoni, T. Hocker, Th. Graule: Quantitative relation-

ships between composition, particle size, triple phase boundary length and surface area in

nickel-cermet anodes for Solid Oxide Fuel Cells, J Power Sources, 196, 7076 7089 (2011).

6. L.M. Keller, L. Holzer, R. Wepf, Ph. Gasser: 3D geometry and topology of pore pathways in

Opalinus clay: Implications for mass transport, Applied Clay Science, 52, 85-95 (2011).

7. M. Linder, T. Hocker, R. Denzler, A. Mai, B. Iwanschitz: Automated, Model-Based Analysis

of Uj-Data for Electrolyte-Supported SOFC Short-Stacks, Fuel Cells, vol. 11, pp. 573-580(2011).

8. E. Knapp, B. Ruhstaller: Numerical impedance analysis for organic semiconductors with

exponential density of localized states, Appl. Phys. Lett. 99, 9, 093304 (2011).

9. E. Knapp, B. Ruhstaller: Numerical analysis of steady-state and transient charge transport

in organic semiconductor devices, Optical and Quantum Electronics (2011).

10. D. Rezzonico, B. Perucco, E. Knapp, R. Häusermann, N.A. Reinke, F. Müller, B. Ruhstaller:Numerical analysis of exciton dynamics in organic light-emitting devices and solar cells, Jour-nal of Photonics for Energy, 1, 011005-1-11 (2011).

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A.3 News Articles

1. N.A. Reinke: Bericht über Winterthur Instruments, Swiss Equity Magazin, 2011

2. N.A. Reinke: Bericht über Winterthur Instruments, Technopark Leaders, 2011

3. N.A. Reinke: Moderne Methoden der Schichtprüfung, Journal für Oberflächentechnik, 2011

4. N.A. Reinke: Moderne Methoden der Schichtprüfung, besser lackieren!, 2011

5. N.A. Reinke: einLeuchtEnD, Aktuelle Technik, März 2011

6. N.A. Reinke, A. Bariska: Schichtdickenmessung, Malerblatt, Mai 2011

7. N.A. Reinke, A. Bariska: Schichtparameter zuverlässig bestimmen, Journal für Oberflächen-technik, April 2011

8. A. Bariska, N.A. Reinke: Berührungslose thermische Schichtprüfung, Swiss Engineering,März 2011

A.4 Book Chapters

1. Y. Safa: Helium Thermodynamics, Analytical Model. Book Chapter, Helium: Characteristics,Compounds, and Applications / Becker Lucas A. (Hrsg.) - Hauppauge, New York, USA: NovaScience Publishers , ISBN/ISSN: 978-1-61761-213-8, 2011.

2. B. Ruhstaller, E. Knapp, B. Perucco, N.A. Reinke, D. Rezzonico, F. Müller: Advanced Numer-

ical Simulation od Organic Light Emitting Devices. Book Chapter, Optoelectronic Devicesand Properties, Oleg Sergiyenko (Ed.), ISBN 978-953-307-204-3, 2011.

A.5 Exhibitions

1. Thurgauer Technologietag 2011, Arbon, April 2011

2. Hannover Messe, Hannover, April 2011

3. Control Messe, Stuttgart, May 2011

4. Winterthurer Nacht der Technik, ZHAW, Winterthur, June 2011

5. Blue-Tech Fachkongress, Casinotheater, Winterthur, September 2011

A.6 Conferences and Workshops

1. Y. Safa, T. Hocker: A new model for detailed simulation of multiple transport and conversion

processes in SOFC stack repeat units, 8th Symposium on Fuel Cell Modeling and Experi-mental Validation, Bonn (Germany), March 2011.

2. A. Evans, R. Tölke, M. Prestat, Y. Safa, T. Hocker, L.J. Gauckler: Free standing yttria sta-

bilised zirconia micro solid oxide fuel cell membranes, EMRS, Nice (France), June 2011.

3. B. Ruhstaller: Parameter extraction by simulation-based characterization of organic solar

cells, Large Area, Organic and Printed Electronics Conference (LOPE-C), Frankfurt (Ger-many), June 2011.

35 ZHAW


4. T. Lanz: Light scattering simulation for thin film silicon solar cells. invited talk, InternationalSimulation Workshop on Organic Electronics and Photovoltaics, Winterthur (Switzerland),June 2011.

5. E. Knapp: Impedance Analysis of Organic Light-Emitting Devices, International SimulationWorkshop on Organic Electronics and Photovoltaics, Winterthur (Switzerland), June (2011).

6. B. Ruhstaller, B. Perucco: On the exciton profile in OLEDs - seamless optical and electri-

cal modelling, International Simulation Workshop on Organic Electronics and Photovoltaics,Winterthur (Switzerland), June 2011.

7. M. Neukom: Charge extraction with linearly increasing voltage: A numerical model for param-

eter extraction, International Simulation Workshop on Organic Electronics and Photovoltaics,Winterthur (Switzerland), June 2011.

8. M. Schmid: Modeling and simulation of small amplitude transients and impedance spec-

tra in DSCs, International Simulation Workshop on Organic Electronics and Photovoltaics,Winterthur (Switzerland), June 2011.

9. A. Evans, R. Tölke, J. Martynczuk, M. Prestat, L.J. Gauckler, Y. Safa, T. Hocker: Thin films

for micro solid oxide fuel cells, SSI, Warsaw (Poland ), July 2011.

10. L. Holzer: Microstructure effects on the activity of SOFC electrodes: basic principles and

preliminary results, Swiss-Korean Workshop, Thin Films for Solid Oxide Fuel Cells, ETHZ,Zurich (Switzerland), July 2011.

11. Y. Safa: Buckling-Driven Crack Growth in Elastic Plate Devices, 21. Symposium Simulation-stechnik der Arbeitsgemeinschaft Simulation (ASIM), Winterthur (Switzerland), September2011.

12. L. Holzer, L. Keller, B. Münch: Quantitative microstructure analysis in materials science, Lec-tures at Summer Academy of Ulm University: Stochastic Analysis, Modelling and Simulationof Complex Structures, Soellerhaus, Kleinwalsertal (Germany), September 2011.

13. L. Holzer, T. Hocker, B. Iwanschitz: Microstructure analysis and modelling related to degrada-

tion of SOFC-electrodes, 2nd int. Workshop on fuel cell degradation, Thessaloniki (Greece),September 2011.

14. B. Perucco, J.O. Schumacher, J. Roth, F.N. Büchi: Two-phase modelling of the membrane

electrode assemblyof PEMFCs, European Fuel Cell–Piero Lunghi Conference, Rome (Italy),December 2011.

15. S. Schönenberger, M. Neukom, B. Ruhstaller: Numerical model and parameter fitting for

more insight into BHJ organic solar cell operation, European Materials Research Society(E-MRS) Symposium, Nice (France), 2011.

16. Y. Safa: Mathematica Implementation of New Simulation Codes for Challenging Industrial

Applications, Der XIII. Mathematica-Tag, Berlin (Germany), 2011.

17. T. Hocker: Assessing the performance and degradation behavior of high-temperature solid

oxide fuel cells, Symposium about Trends in Thermodynamics and Materials Theory, Berlin(Germany), 2011.

18. M. Neukom, S. Züfle, N.A. Reinke, B. Ruhstaller: Charge extraction with linearly increasing

voltage: A numerical model for parameter extraction, DPG Frühjahrstagung 2011, Dresden(Germany), 2011.

19. A. Evans, R. Tölke, J. Martynczuk, M. Prestat, Z. Yáng, M.V.F. Schlupp, L.J. Gauckler, Y.Safa, T. Hocker: Development of miniaturized solid oxide fuel cells on silicon chips, ECERS,Stokholm (Sweden), 2011.

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A.7 Prizes and Awards

1. N.A. Reinke and A. Bariska, Heuberger Winterthur Jungunternehmerpreis 2011

2. N.A. Reinke and A. Bariska, VentureKick-Award I&II&III

3. N.A. Reinke and A. Bariska, Invited Exhibitor @ Innovation Japan 2011

4. N.A. Reinke and A. Bariska, Volkswirtschaft-Stiftung Förderung

5. N.A. Reinke and A. Bariska, Invited Exhibitor @ Sonderschau Berührungslose Messtechnik

Control 2010 & 2011

6. N.A. Reinke and A. Bariska, Top 20 Innovation Hannover Messe 2011

7. N.A. Reinke and A. Bariska, VentureLeaders Award

8. B. Ruhstaller, Invited Exhibitor @ PV Expo 2011, Tokyo, Japan

A.8 Teaching

Bachelor of Science

• Analysis I&II – R. Axthelm

• Lineare Algebra I – R. Axthelm

• Lineare Algebra I – M. Schmid

• Mensch Technik Umwelt – T. Hocker

• Organische Elektronik und Photovoltaik – B. Ruhstaller

• Thermo-Fluiddynamik III – T. Hocker

• Physik Felder & Wellen – M. Bonmarin

• Physik I – M. Bonmarin

• Physik I&II – N.A. Reinke

• Physik I&II – M. Schmid

• Physik I&II – J.O. Schumacher

• Sensorik – N.A. Reinke

Master of Science

• Applied Photonics – B. Ruhstaller

• Multiphysics Modelling and Simulation – J.O. Schumacher

• Advanced Thermodynamics – J.O. Schumacher

• Mathematical Methods (www.pv-master.com) – J.O. Schumacher

Summer Schools

• SOFC Modeling and Design, Joint European Summer School for Fuel Cell and HydrogenTechnology (Italy) – T. Hocker

37 ZHAW


A.9 Spin-off Companies

www.nmtec.ch

Numerical Modelling GmbH works in the field of Computer Aided Engineering (CAE) and offersservices and simulation tools for small and medium enterprises. Our core competence is knowl-edge transfer: we bridge the gap between scientific know-how and its application in the industry.With our knowledge from physics, chemistry and the engineering sciences we are able to pro-foundly support your product development cycle. Numerical Modelling speaks your language andis able to conform to given constraints with respect to time and budget.We often create so-called customer specific CAE tools in which the scientific knowledge requiredfor your product is embedded. In this form, it is easily deployed within your R&D departmentand supports actual projects as well as improving the skills of your staff. Ask for our individualconsulting service which covers all areas of scientific knowledge transfer without obligation.

www.fluxim.com

FLUXiM is a provider of device simulation software to the display, lighting, photovoltaics and elec-tronics industries worldwide. Our principal activity is the development and the marketing of thesimulation software SETFOS which was designed to simulate light emission from thin film devicessuch as organic light-emitting diodes (OLEDs), thin film solar cells (organic and inorganic) andorganic semiconducting multilayer systems.Our company name FLUXiM is derived from flux simulation. Our software products are usedworldwide in industrial and academic research labs for the study of device physics and productdevelopment. Check out our references and testimonials for more info. We develop swiss-madesoftware in Switzerland and in addition also provide services such as consulting, training andsoftware development, see services page for more details.

www.winterthurinstruments.ch

Winterthur Instruments GmbH develops measurement systems for fast non contact and non de-structive testing of industrial coatings. These measurement systems can be used to determinecoating thicknesses, material parameters (e.g. porosity) and contact quality (e.g. to detect delami-nation). The system is based on optical-thermal measurements and works with all types of coatingand substrate materials. Our measurement systems provide the unique opportunity of non-contactand non-destructive testing of arbitrary coatings on substrates.

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http://www.nmtec.ch/

http://www.fluxim.com/

http://www.winterthurinstruments.ch/


A.10 ICP-Team

Name Function e-Mail

Dr. Rebekka Axthelm Research Associate [email protected]. Mathias Bonmarin Research Associate [email protected] Brossi Research Assistant [email protected]. Peter Cendula Research Associate [email protected] Hauri Research Assistant [email protected]. Dr. Thomas Hocker Lecturer, Head ICP [email protected]. Lorenz Holzer Research Associate [email protected] Kaufmann Research Assistant [email protected]. Lukas Keller Research Associate [email protected] Knapp Research Associate [email protected] Lanz Research Assistant [email protected] Lapagna Research Assistant [email protected] Linder Research Assistant [email protected] Meier Research Assistant [email protected] Pecho Research Associate [email protected] Perucco Research Associate [email protected]. Nils Reinke Lecturer [email protected] Ritzmann Research Assistant [email protected]. Dr. Beat Ruhstaller Lecturer, Dep. Head ICP [email protected]. Yasser Safa Research Associate [email protected]. Guido Sartoris Research Associate [email protected]. Matthias Schmid Research Associate [email protected]. Dr. Jürgen Schumacher Lecturer [email protected] Spiess Administrative Assistant [email protected] Toniolo Administrative Assistant [email protected] Züfle Research Assistant [email protected]

The following visiting scientists were staying at the ICP during the last year:

• Prof. Dr. Seung Jae Baik, research partner, Korea Advanced Institute of Technology (KAIST),South Korea

• Matthias Neumann, Ulm University, Ulm, Germany

• Felipe Augusto Brasileiro, IAESTE Exchange Student, Universidade Estadual de Campinas,Saõ Paulo, Brasil

39 ZHAW

mailto:[email protected]



























A.11 Location

ICP Institute ofComputational Physics

Technikumstrasse 9P.O. BoxCH-8401 Winterthur

www.icp.zhaw.ch

ContactThomas HockerPhone +41 58 934 78 [email protected]

AdministrationLilian TonioloPhone +41 58 934 73 [email protected]

TK-Building TL-Building

ZHAW 40



http://map.search.ch/winterthur/wildbachstr.21

Zurich University

of Applied Sciences

School ofEngineering

ICP Institute ofComputational Physics

Technikumstrasse 9

P.O. Box

CH-8401 Winterthur

Phone +41 58 934 71 71

[email protected]

www.icp.zhaw.ch

zhaw icp research report 2011

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