7 european kesteriteworkshop overview
TRANSCRIPT
CONFIDENTIAL – INTERNAL USE
Organized by
Funded by
7TH EUROPEAN KESTERITE WORKSHOP
OVERVIEW
CONFIDENTIAL – INTERNAL USE2
CONFIDENTIAL – INTERNAL USE
SESSION 1 – IMPACT OF GE ON ABSORBER FORMATION
Thomas Schnabel, ZSW
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Cu2ZnSnSxSe4-x
12.6 % (10.3% ZSW)
Cu2ZnGeSxSe4-x
(DMSO)
3.3 %
Poor reproducibility
Cu2ZnGeSxSe4-x
(H2O)
2.1 %
Strong C-residues
Cu2ZnGeSxSe4-x
(DMF)
6.0 %
Very homogeneous
Cu2ZnSiySn1-ySxSe4-x
No efficiencies
Mostly secondary phases
CONFIDENTIAL – INTERNAL USE
SESSION 1 – IMPACT OF GE ON ABSORBER FORMATION
Sergio Giraldo, IREC
Ge doping strategies lead to an improved performance of CZTSe solar cells compared to our
former methodology without using Ge:
Ge front nanolayer: VOC increase
Ge front+back approach: JSC increase (Eff ~10 %)
Guy Brammertz, imec
Large grains and good crystallinity with little secondary phases can be obtained
Substrate type and metal stacking order have a large influence on the absorber properties
Best solar cell fabricated up to date has an efficiency of 5.5 %
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CONFIDENTIAL – INTERNAL USE
SESSION 2 – KESTERITE ABSORBER
OPTIMIZATION
Alain Lafond, IMN
Substitution of Li for Cu
Band-gap from 1.5 - 1.9 eV
Suitable as top cell of tandem solar cells
Insertion of Li could lower the Cu/Zn disorder
Stefan Haaß, Empa
For each alkali metal and concentration separate
adjustment of Sn content mandatory
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0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
0.0
0.2
0.4
0.6
0.8
1.0
K/M
(a
rbitra
ry u
nits)
Energy (eV)
x=0
x=0.22
x=0.30
x=0.36
x=0.76
x=1
CONFIDENTIAL – INTERNAL USE
SESSION 2 – KESTERITE ABSORBER
OPTIMIZATION
Chang Yan, UNSW
By optimizing the CZTS baseline and the ZnCdS
buffer, 9.7 % efficiency pure sulfide CZTS device
(total 0.24 cm2) is achieved in our lab
Yi Ren, Uppsala University
Impact of SnS secondary phases on Cu2ZnSnS4 thin film solar cells:
We observed the SnS phase condensed on CZTS surface is not useful for solar cells
We discovered that the SnS on rear CZTS could be beneficial to the current of solar cells
We discussed SnS can possibly benefit thin solar cells via the passivation effect
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CONFIDENTIAL – INTERNAL USE
SESSION 3 – STRUCTURAL PROPERTIES OF KESTERITE ABSORBERS
Jose Marquez, Northumbria University
Study of the importance and influence of the tetragonal distortion (c/2a) on the properties of
CZTSSe absorbers and devices, keep it low!
A simplified approach has been proposed for evaluating the tetragonal distortion that might be
used to correlate:
Metal ratios, ordering level and/or Ge incorporation
Charles Hages, HZB
Interpreting Time Resolved Photoluminescense for Kesterites
PL decay does not follow SRH recombination (Carrier Redistribution / Minority Carrier de-trapping)
Minority Carrier Lifetime is hundreds of picoseconds rather than a few nanoseconds
Common pitfalls in analyzing TRPL data
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CONFIDENTIAL – INTERNAL USE
SESSION 3 – STRUCTURAL PROPERTIES OF KESTERITE ABSORBERS
Mikhail Sulimov, Strathclyde University / Ural Federal University
Effects of [Cu]/[Zn+Sn] ratio on optical spectra of Cu2ZnSnSe4 thin films
The changes in the optical spectroscopy parameters along with improvements in the solar cell
performance are consistent with a reduction of the CuZn defect population, rising
concentration of VCu and ZnCu-VCu as well as with increasing ordering of Cu and Zn atoms in
the (001) plane
Elisa Valle-Rios, HZB
Intrinsic point defects in off-stoichiometic
kesterite CZTSe types
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CONFIDENTIAL – INTERNAL USE
SESSION 4 – PROGRESS IN HETEROJUNCTION FORMATION
Haibing Xie, IREC
Epitaxial growth of Al(OH)3 nanolayers using a facile wet chemical treatment
Considerable enhancement of VOC, FF and conversion efficiency of CZTSSe solar cells
Best efficiency of 9.1 % (NO ARC) was obtained for a Se-rich CZTSSe solar cell
Tove Ericson, Uppsala University
Zn1-xSnxOy band gap was varied by ALD process temperature
highest VOC for 145 °C
highest FF for 165 °C
both with better efficiency than their CdS reference
Cd-free Cu2ZnSnS4 cell with 9.0 % efficiency (incl. AR)
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CONFIDENTIAL – INTERNAL USE
SESSION 4 – PROGRESS IN HETEROJUNCTION FORMATION
Andrea Crovetto, Technical University of Denmark
An epitaxial Cu2ZnSnS4/CeO2 interface can be achieved at 50˚C
Works successfully as a passivation layer
Tends to block current: must be as thin as possible (atomic layer dep.?)
Cannot be a stand-alone buffer layer
This materials search approach could be used for other candidate materials
Leo Choubrac, IMN
CdIn2S4 buffer layer
Collection length & VOC can be as good as CdS
JSC can be improved
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0%
20%
40%
60%
80%
100%
300 500 700 900 1100 1300
CONFIDENTIAL – INTERNAL USE11
CONFIDENTIAL – INTERNAL USE
SESSION 5 – PROGRESS IN REAR CONTACT AND SUBSTRATE
Moises Espindola-Rodriguez, IREC
Several functionalized transparent
conductive oxides have been tested as
back contact for Kesterite solar cells:
The most promising metal-oxide are :
MoO3, V2O5 and TiO2 (n-type).
FTO/Mo works better for possible tandem
and bifacial structures.
The back interface still needs to be
optimized
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Mo
FTO
Glass
i:ZnO/ITO
CdS
CZTSSe
FRONT (ITO)
Abet Class AAA Solar Simulator
AM1.5G
REAR (Glass)
Oriel Class A BB Solar Simulator
AM1.5G
Mo
FTO
Glass
i:ZnO/ITO
CdS
CZTSSe
FRONT (ITO)
Abet Class AAA Solar Simulator
AM1.5G
REAR (Glass)
Oriel Class A BB Solar Simulator
AM1.5G
Si-HIT-Cell
CONFIDENTIAL – INTERNAL USE
SESSION 5 – PROGRESS IN REAR CONTACT AND SUBSTRATE
Markus Neuschitzer, IREC
It is possible to fabricate CZTSe devices at T < 500ºC on polyimide (eff. = 4.9 %) and on SLG (eff. = 6.4 %)
NaF and KF are effective strategies to dope the CZTSe absorber at low T
Samaneh Ranjbar, imec
Enhancement of
back contact by introducing a MoO3-x
interfacial layer
p-n junction by introducing a TiO2 interfacial layer
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CONFIDENTIAL – INTERNAL USE
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