PERMASOLPerovskite Materials for Efficient Solar CellsEnergieforschungsprogramm – 1. AusschreibungEmerging Technologies

Theodoros DimopoulosSenior Scientist, AIT Austrian Institute of Technology, Center for Energy, Photovoltaic Systems

Motivation

Why emerging materials are important for PV?

2 °C global warming scenario*: IEA predicts worldwide electricity

demand of 33 000 TWh in 2050

This corresponds to 25 TWp of installed PV capacity (assumingannual average capacity factor of 15%)

*Energy Technology Perspectives 2014, International Energy Agency, 2014

Motivation

2010 2015 2020 2025 2030 2035 2040 2045 2050 2055

0

5000

10000

15000

20000

2500025 TWp

700 GWp

ca

pa

city (

GW

p)

year

300 GWp

Abundance and processing

How fast can we produce raw material?

a-Si (1 m), CdTe (800 y), CIGS (300 y)

c-Si (3 y)

Flexible TFPV

OPV (minutes)

J. Jean et al. Pathways for solar photovoltaics, Energy Env.

Sci. 8 (2015) 1200–1219. doi:10.1039/C4EE04073B. (MIT)

Abundance and processing

How fast can we produce raw material? How fast can we produce efficient PV

modules?

J. Jean et al. Pathways for solar photovoltaics, Energy Env.

Sci. 8 (2015) 1200–1219. doi:10.1039/C4EE04073B. (MIT)

Source: Heliatek

Efficiency

Efficiency

Perovskite cells with soaring efficiencies(max. 22.1%)

[1] Kojima et al., J. Am. Chem. Soc. 2009, 131, 6050−6051.[2] Saliba, M. et al., Science 2016, 354, 206−209.

ABX3

Pb perovskites - properties

A

B

X BX6

A: organic cation (e.g. CH3NH3+)B: PbX: halogen I, Cl, Br

Source: ossila

Hybrid & abundant: one componentorganic and one inorganic

They can be synthesized from inks They can be easily applied by spin coating /

knife coating / printing …. methods They are very efficient solar absorbers

research.utdallas.edu flexoglobal.com

Problems regarding Pb perovskite

It contains Pb which is a toxic material [1] Limited environmental stability [2] Danger with Pb is related to the low stability

High temperature solar cell processing steps (DSSC architecture) are incompatible with flexible substrates

[1] Babayigit, A. et al., Toxicity of Organometal Halide Perovskite Solar Cells. Nat. Mater. 2016, 15, 247−251.[2] Leijtens, T. et al., Stability of Metal Halide Perovskite Solar Cells. Adv. Energy Mater. 2015, 5, 1500963.

PERMASOL

The project seeks to replace Pb perovskite with a less toxic and more stablealternative Replace the processes, which are not compatible with flexible substrates Unveil the mechanicms of carrier transport in perovskite cells

Duration: 01.09.2015 -31.08.2018

Partnerso AIT (Coordinator)o TU Graz, ICTM o Joanneum Research o University of Patras (subcontractor)

Substitutes for Pb

Appropriate ion sizes [1]

Appropriate oxidation state 2+ (e.g. Sn2+)

Appropriate semiconductor properties (bandgap, carrier mobility,….)

𝑜𝑐𝑡𝑎ℎ𝑒𝑑𝑟𝑎𝑙 𝑓𝑎𝑐𝑡𝑜𝑟: 𝜇 =𝑅𝐵𝑅𝑋

, 0.442 ≤ 𝜇 ≤ 0.895

𝑡𝑜𝑙𝑒𝑟𝑎𝑛𝑐𝑒 𝑓𝑎𝑐𝑡𝑜𝑟: 𝑡 =(𝑅𝐴 + 𝑅𝑋)

2(𝑅𝐵 + 𝑅𝑋), 0.8 ≤ 𝑡 ≤ 1.0

A

B

X BX6

ABX3, ionic radii: RA, RB, RX

[1] Goldschmidt VM (1926) Naturwissenschaften 14:477

Substitutes for Pb

0D perovskite-like hybridsA3B2X9

2D perovskiteA2BX4

3D perovskiteABX3

From 3D to low dimensionality

Low D: better solution processability / environmental stability Quantum confinement influences electronic properties

Stoumpos et al., Chem. Mater. 2016, 28, 2852−2867

A2Cn−1BX3n+1

Ab-initio band-structure simulations

Simulation of electronic and structural properties Vienna ab-initio simulation package (VASP) Density functional theory DFT Different approximations (LDA and GGA) and functionals (PBE0, HSE06)

>50 different materials simulated, combinations of:o Ge2+,Sn2+,Pb2+ (reference) ; Cu2+; Bi3+,….o A=MA+, FA+, Cs+, K+, Rb+

o X=Cl-, I-, Br-, F-

Ab-initio band-structure simulations

Calculating the equilibrium state and lattice constant of the perovskite Calculation of the density of states – extraction of bandgap

Ab-initio band-structure simulations

Calculation of orbitals comprising the density of states Interaction of similar orbitals (e.g. p-type Pb-I, Bi-I) gives small bandgap Dissimilar orbitals (e.g. Ba-I) leads to large bandgap

30 µm30 µm

A3Bi2X9 perovskites forming hexagonally-shaped micro crystals (9-18 µm)

Crystallization in the expected structure Tunable bandgap (1.67-3 eV): appropriate

for solar absorber

Bi (III) / X=I, Cl / A=MA, FA, K, Cs

Bi (III) / X=I,Cl / A=MA, FA, K, Cs

MA3Bi2I9 MA3Bi2I9-xClx

Solar cells of the DSSC and of the organic type were fabricated Max. efficiency 0.18%, max Voc 0.6 V, max jsc 0.8 mA/cm

2

Cu (II) / X=I, Cl, Br / A=MA

MA2CuCl4-xBrx is a 2D perovskite Easily processed on many substrates Br content tunes the bandgap (2.84 eV – 1.73 eV)

Cu (II) / X=I, Cl, Br / A=MA

Crystallization as flat yellow-brown platelets that cleave easily in theplane of the platelets

Uniform flat films over large areas Environmentally stable

MAGeI3

MAGeBr3

10 20 30 40 50 60 70 80

32.5 35.0 37.5 40.0 42.5 45.0 47.5

(CH3NH

3)I

Inte

nsity (

arb

. u

nit)

Diffraction angle, 2 (deg)

(CH3NH

3)GeI

3

Inte

nsity (

arb

. u

nit)

MAGeI3

Easily processible on different substrates Particularly unstable in ambient conditions

(oxidation from Ge2+ to Ge4+) Challenging characterization MAGeI3 bandgap 1.8 eV

Ge (II) / X=I,Br / A=MA, FA, Cs

MAGeI3 MAGeI2Br

-0.5 0.0 0.5

-0.0002

-0.0001

0.0000

0.0001

0.0002

0.0003

MAGeI2Br asc., n=0.19%

MAGeI2Br desc., n=0.16%

MAGeI3 asc., n=0.21%

MAGeI3 desc., n=0.20%

cu

rren

t (A

)

bias (V)

Ge (II) / X=I,Br / A=MA, FA, Cs

Materials: MAGeI3 (1.8-2 eV), MAGeI2Br (2.3 eV), CsGeI3, (1.73 eV), FAGeI3 (2.1-2.62 eV)

Ge perovskite processible in N2 atmosphere Particularly unstable in ambient conditions Max. efficiency ~0.5% (organic cell architecture)

n=0.46%

200 nm

200 nm

2 µm

200 nm

Glass/FTO Glass/FTO

Glass/AZO/Au/AZO PET/AZO/Au/AZO

Other tasks

Low temperature deposition of 3D ETM based on ZnO nanorods Synthesis of nanoparticles for HTM (e.g. NiO, MoOx) Time resolved spectroscopy to probe carrier relaxation mechanisms /

effect of interfaces with HTM and ETM

Next steps

Focusing on the materials with the highest potential Investigate solar cells of the DSSC and OPV type Time resolved spectroscopic methods for cells of different architecture Environmental stability of the perovskites

Dissemination

4 participations in international conferences (2 HOPV2016, 1 MRS 2017, 1 E-MRS 2017)

2 peer-reviewed publications1) Hoefler, Trimmel, Rath, Monatsh Chem., „Progress on lead-free metal

halide perovskites for photovoltaics applications: a review”, DOI 10.1007/s00706-017-1933-9 (2017)

2) Ebner, Bauch, Dimopoulos, High performance and low cost transparent electrodes based on ultrathin Cu layer, Optics Express (2017)

1 publications under review

1 Master thesis – Ms. Paula Santos-Ortiz

The PERMASOL team

Thank you !