Ge incorporated Cu2ZnSnSe4 thin-film solar cells
Shinho Kim Kang Min Kim Hitoshi Tampo Hajime Shibata and Shigeru Niki
National Institute of Advanced Industrial Science and Technology (AIST)
Research Center for Photovoltaics (RCPV) Compound Semiconductor Thin Film Team
bull In Ga rarr Zn Sn bull High absorption
coefficient ndash αgt 104 cm-1
bull Using the earth abundant materials
bull Production cost down
Introduction ndash Kesterite solar cells
Cu In Ga Se
Cu Zn Sn SSe
I III VI III
I II VI IV
Cu2InxGa1-xSe4
Cu2ZnSnSe4
CZT(S)Se
1
Introduction ndash Band gap tuning of kesterite thin films
bull The control of S(S+Se) ratio is difficult
due to the high volatility of the anionic
components
bull Large VOC deficit (Egq-VOC) with S
incorporation 1
bull CZTSe asymp 0577 mV rarr CZTSSe asymp 0647 (at
champion cells respectively)
bull Ex) CIGSe asymp 05
bull Low FF 2
bull Low VOC and high ideality factor (A)
bull Secondary phase problems
Problems of S incorporation
2
Cu2ZnSn(SxSe)4 Cu2ZnSnSe4
150 eV 100
-015 000
~10 lt Eg(CZT(SxSex-1)) lt ~15 eV
Band gap tuning with S incorporation
1 A Polizzotti et al Energy amp Environmental Science 6 (11) 3171-3182 (2013) 2 K F Tai et al Advanced Energy Materials 6 (3) (2016)
3
bull Tunable band-gap using cationic element rarr ~10ltEg(CZTGSe)lt~15eV controlled by Ge(Sn+Ge) ratio
bull Reduced VOC deficit bull Large grain growth caused by GeSe2 liquid phase
Ge incorporated CZTSe (CZTGSe) CZTGSe
07 08 09 10 11 12 13 14 15 160
2
4
6
8
10
(ahυ
)2 times 1
08 ((eV
cm)2 )
Energy (eV)
Ge(Sn+Ge) Ge=000 Ge=028 Ge=051 Ge=064 Ge=079 Ge=100
1 μm
Cell Eff ()
VOC (V)
JSC (mAcm2)
FF ()
Eg (eV) Eg q-VOC
CZTGSSe Perdue Univ (2013) 1 940 0460 319 638 119 0730
CZTGSe AIST (2015) 2 1003 0543 295 627 119 0647
CZTSe IREC(2015) 3 1060 0473 343 651 103 0550
CZTGSe Univ of Washington (2016) 4 1100 0583 336 559 130 0717
I-V Results of Ge incorporated Cells
4
1 C J Hages et al Progress in Photovoltaics Research and Applications 23 (3) 376-384 (2013) 2 S Kim et al Solar Energy Materials and Solar Cells 144 488-492 (2016) 3 S Giraldo et al Advanced Energy Materials 5 (21) (2015) 4 A D Collord and H W Hillhouse Chemistry of Materials 28 (7) 2067-2073 (2016)
5
Experimental Procedure
SLG Mo
CZTGSe CdS
i-ZnO AZO
Al
As grown CZTGSe deposited by co-evaporation method Composition Control
Annealing using two zone furnace Grain Growth
Co-evaporation Annealing
CZTGSe solar cell structure
Ge
SLG Mo
Heater 200
Sample Pellets
Internal gases flow
00 01 02 03 04 050
10
20
30
J (m
Ac
m2 )
V (V)
Eff VOC JSC FF 12322 0527 32157 0727
400 600 800 1000 120000
02
04
06
08
10
EQ
E (
)
Wavelength (nm)
09 10 11 12 1300
02
04
06
08
10
[E ln
(1-E
QE
)]2
Energy (eV)
Eg=11eV
New efficiency of Ge incorporated kesterite solar cell
bull The highest efficiency of Ge incorporated kesterite solar cell greater than 12
6
7
Device parameters
Cell Eff ()
VOC (V)
JSC (mAcm2) FF Rs
(Ωcm2) Rsh
(Ωcm2) A J0 (A cm2)
Eg (eV) Egq-VOC
CZTSSe IBM (2013) 1260 0513 352 0698 072 621 145 70E-8 113 0617
CZTGSe AIST (2015) 1003 0543 295 0627 020 694 249 63E-6 119 0647
CZTGSe AIST (2016) 1232 0527 322 0727 036 1111 147 36E-8 111 0583
bull Highly improved fill factor over 07 bull Reduced device parameters ndash A Jo and VOC deficit rarr Improved junction quality and reduced carrier recombination in SCR
05 10 15 20 25 30
0
2
4
6
8
10
12 Efficiency FF
ZnIVE
ffici
ency
()
02
03
04
05
06
07
08
FF
Atomic ratio of CZTGSe thin films (EPMA)
bull Efficiency shows similar tendency with FF bull Optimized surface conditions are observed at CuZn=19 and ZnIV=12
04 06 08 10 12 14 16 18 20
2
4
6
8
10
12 Efficiency FF
CuZn
Effic
ienc
y (
)
030
035
040
045
050
055
060
065
070
075
FF
Surface composition ~ 120 nm
8
0 10 20 30 40 501
10
100
1000
10000
PL
Inte
nsity
(cou
nts)
Time (ns)
Decay curve Fit
τ2 = 56 ns
Lifetime measurement by TRPL Cell Eff () Lifetime (ns)
CZTSSe IBM (2013) 1260 67
CZTGSe AIST (2015) 1003 25
CZTGSe AIST (2016) 1232 56
09 10 11 12 13
PL In
tens
ity (a
rb u
nits
)
Energy (eV)
Eg = 11 eVEgopt = 108 eV bull Improved carrier life time bull PL peak is closed to the
band edge position (asymp003) ndash it may be beneficial effect in reducing VOC deficit
9
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
bull In Ga rarr Zn Sn bull High absorption
coefficient ndash αgt 104 cm-1
bull Using the earth abundant materials
bull Production cost down
Introduction ndash Kesterite solar cells
Cu In Ga Se
Cu Zn Sn SSe
I III VI III
I II VI IV
Cu2InxGa1-xSe4
Cu2ZnSnSe4
CZT(S)Se
1
Introduction ndash Band gap tuning of kesterite thin films
bull The control of S(S+Se) ratio is difficult
due to the high volatility of the anionic
components
bull Large VOC deficit (Egq-VOC) with S
incorporation 1
bull CZTSe asymp 0577 mV rarr CZTSSe asymp 0647 (at
champion cells respectively)
bull Ex) CIGSe asymp 05
bull Low FF 2
bull Low VOC and high ideality factor (A)
bull Secondary phase problems
Problems of S incorporation
2
Cu2ZnSn(SxSe)4 Cu2ZnSnSe4
150 eV 100
-015 000
~10 lt Eg(CZT(SxSex-1)) lt ~15 eV
Band gap tuning with S incorporation
1 A Polizzotti et al Energy amp Environmental Science 6 (11) 3171-3182 (2013) 2 K F Tai et al Advanced Energy Materials 6 (3) (2016)
3
bull Tunable band-gap using cationic element rarr ~10ltEg(CZTGSe)lt~15eV controlled by Ge(Sn+Ge) ratio
bull Reduced VOC deficit bull Large grain growth caused by GeSe2 liquid phase
Ge incorporated CZTSe (CZTGSe) CZTGSe
07 08 09 10 11 12 13 14 15 160
2
4
6
8
10
(ahυ
)2 times 1
08 ((eV
cm)2 )
Energy (eV)
Ge(Sn+Ge) Ge=000 Ge=028 Ge=051 Ge=064 Ge=079 Ge=100
1 μm
Cell Eff ()
VOC (V)
JSC (mAcm2)
FF ()
Eg (eV) Eg q-VOC
CZTGSSe Perdue Univ (2013) 1 940 0460 319 638 119 0730
CZTGSe AIST (2015) 2 1003 0543 295 627 119 0647
CZTSe IREC(2015) 3 1060 0473 343 651 103 0550
CZTGSe Univ of Washington (2016) 4 1100 0583 336 559 130 0717
I-V Results of Ge incorporated Cells
4
1 C J Hages et al Progress in Photovoltaics Research and Applications 23 (3) 376-384 (2013) 2 S Kim et al Solar Energy Materials and Solar Cells 144 488-492 (2016) 3 S Giraldo et al Advanced Energy Materials 5 (21) (2015) 4 A D Collord and H W Hillhouse Chemistry of Materials 28 (7) 2067-2073 (2016)
5
Experimental Procedure
SLG Mo
CZTGSe CdS
i-ZnO AZO
Al
As grown CZTGSe deposited by co-evaporation method Composition Control
Annealing using two zone furnace Grain Growth
Co-evaporation Annealing
CZTGSe solar cell structure
Ge
SLG Mo
Heater 200
Sample Pellets
Internal gases flow
00 01 02 03 04 050
10
20
30
J (m
Ac
m2 )
V (V)
Eff VOC JSC FF 12322 0527 32157 0727
400 600 800 1000 120000
02
04
06
08
10
EQ
E (
)
Wavelength (nm)
09 10 11 12 1300
02
04
06
08
10
[E ln
(1-E
QE
)]2
Energy (eV)
Eg=11eV
New efficiency of Ge incorporated kesterite solar cell
bull The highest efficiency of Ge incorporated kesterite solar cell greater than 12
6
7
Device parameters
Cell Eff ()
VOC (V)
JSC (mAcm2) FF Rs
(Ωcm2) Rsh
(Ωcm2) A J0 (A cm2)
Eg (eV) Egq-VOC
CZTSSe IBM (2013) 1260 0513 352 0698 072 621 145 70E-8 113 0617
CZTGSe AIST (2015) 1003 0543 295 0627 020 694 249 63E-6 119 0647
CZTGSe AIST (2016) 1232 0527 322 0727 036 1111 147 36E-8 111 0583
bull Highly improved fill factor over 07 bull Reduced device parameters ndash A Jo and VOC deficit rarr Improved junction quality and reduced carrier recombination in SCR
05 10 15 20 25 30
0
2
4
6
8
10
12 Efficiency FF
ZnIVE
ffici
ency
()
02
03
04
05
06
07
08
FF
Atomic ratio of CZTGSe thin films (EPMA)
bull Efficiency shows similar tendency with FF bull Optimized surface conditions are observed at CuZn=19 and ZnIV=12
04 06 08 10 12 14 16 18 20
2
4
6
8
10
12 Efficiency FF
CuZn
Effic
ienc
y (
)
030
035
040
045
050
055
060
065
070
075
FF
Surface composition ~ 120 nm
8
0 10 20 30 40 501
10
100
1000
10000
PL
Inte
nsity
(cou
nts)
Time (ns)
Decay curve Fit
τ2 = 56 ns
Lifetime measurement by TRPL Cell Eff () Lifetime (ns)
CZTSSe IBM (2013) 1260 67
CZTGSe AIST (2015) 1003 25
CZTGSe AIST (2016) 1232 56
09 10 11 12 13
PL In
tens
ity (a
rb u
nits
)
Energy (eV)
Eg = 11 eVEgopt = 108 eV bull Improved carrier life time bull PL peak is closed to the
band edge position (asymp003) ndash it may be beneficial effect in reducing VOC deficit
9
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
Introduction ndash Band gap tuning of kesterite thin films
bull The control of S(S+Se) ratio is difficult
due to the high volatility of the anionic
components
bull Large VOC deficit (Egq-VOC) with S
incorporation 1
bull CZTSe asymp 0577 mV rarr CZTSSe asymp 0647 (at
champion cells respectively)
bull Ex) CIGSe asymp 05
bull Low FF 2
bull Low VOC and high ideality factor (A)
bull Secondary phase problems
Problems of S incorporation
2
Cu2ZnSn(SxSe)4 Cu2ZnSnSe4
150 eV 100
-015 000
~10 lt Eg(CZT(SxSex-1)) lt ~15 eV
Band gap tuning with S incorporation
1 A Polizzotti et al Energy amp Environmental Science 6 (11) 3171-3182 (2013) 2 K F Tai et al Advanced Energy Materials 6 (3) (2016)
3
bull Tunable band-gap using cationic element rarr ~10ltEg(CZTGSe)lt~15eV controlled by Ge(Sn+Ge) ratio
bull Reduced VOC deficit bull Large grain growth caused by GeSe2 liquid phase
Ge incorporated CZTSe (CZTGSe) CZTGSe
07 08 09 10 11 12 13 14 15 160
2
4
6
8
10
(ahυ
)2 times 1
08 ((eV
cm)2 )
Energy (eV)
Ge(Sn+Ge) Ge=000 Ge=028 Ge=051 Ge=064 Ge=079 Ge=100
1 μm
Cell Eff ()
VOC (V)
JSC (mAcm2)
FF ()
Eg (eV) Eg q-VOC
CZTGSSe Perdue Univ (2013) 1 940 0460 319 638 119 0730
CZTGSe AIST (2015) 2 1003 0543 295 627 119 0647
CZTSe IREC(2015) 3 1060 0473 343 651 103 0550
CZTGSe Univ of Washington (2016) 4 1100 0583 336 559 130 0717
I-V Results of Ge incorporated Cells
4
1 C J Hages et al Progress in Photovoltaics Research and Applications 23 (3) 376-384 (2013) 2 S Kim et al Solar Energy Materials and Solar Cells 144 488-492 (2016) 3 S Giraldo et al Advanced Energy Materials 5 (21) (2015) 4 A D Collord and H W Hillhouse Chemistry of Materials 28 (7) 2067-2073 (2016)
5
Experimental Procedure
SLG Mo
CZTGSe CdS
i-ZnO AZO
Al
As grown CZTGSe deposited by co-evaporation method Composition Control
Annealing using two zone furnace Grain Growth
Co-evaporation Annealing
CZTGSe solar cell structure
Ge
SLG Mo
Heater 200
Sample Pellets
Internal gases flow
00 01 02 03 04 050
10
20
30
J (m
Ac
m2 )
V (V)
Eff VOC JSC FF 12322 0527 32157 0727
400 600 800 1000 120000
02
04
06
08
10
EQ
E (
)
Wavelength (nm)
09 10 11 12 1300
02
04
06
08
10
[E ln
(1-E
QE
)]2
Energy (eV)
Eg=11eV
New efficiency of Ge incorporated kesterite solar cell
bull The highest efficiency of Ge incorporated kesterite solar cell greater than 12
6
7
Device parameters
Cell Eff ()
VOC (V)
JSC (mAcm2) FF Rs
(Ωcm2) Rsh
(Ωcm2) A J0 (A cm2)
Eg (eV) Egq-VOC
CZTSSe IBM (2013) 1260 0513 352 0698 072 621 145 70E-8 113 0617
CZTGSe AIST (2015) 1003 0543 295 0627 020 694 249 63E-6 119 0647
CZTGSe AIST (2016) 1232 0527 322 0727 036 1111 147 36E-8 111 0583
bull Highly improved fill factor over 07 bull Reduced device parameters ndash A Jo and VOC deficit rarr Improved junction quality and reduced carrier recombination in SCR
05 10 15 20 25 30
0
2
4
6
8
10
12 Efficiency FF
ZnIVE
ffici
ency
()
02
03
04
05
06
07
08
FF
Atomic ratio of CZTGSe thin films (EPMA)
bull Efficiency shows similar tendency with FF bull Optimized surface conditions are observed at CuZn=19 and ZnIV=12
04 06 08 10 12 14 16 18 20
2
4
6
8
10
12 Efficiency FF
CuZn
Effic
ienc
y (
)
030
035
040
045
050
055
060
065
070
075
FF
Surface composition ~ 120 nm
8
0 10 20 30 40 501
10
100
1000
10000
PL
Inte
nsity
(cou
nts)
Time (ns)
Decay curve Fit
τ2 = 56 ns
Lifetime measurement by TRPL Cell Eff () Lifetime (ns)
CZTSSe IBM (2013) 1260 67
CZTGSe AIST (2015) 1003 25
CZTGSe AIST (2016) 1232 56
09 10 11 12 13
PL In
tens
ity (a
rb u
nits
)
Energy (eV)
Eg = 11 eVEgopt = 108 eV bull Improved carrier life time bull PL peak is closed to the
band edge position (asymp003) ndash it may be beneficial effect in reducing VOC deficit
9
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
3
bull Tunable band-gap using cationic element rarr ~10ltEg(CZTGSe)lt~15eV controlled by Ge(Sn+Ge) ratio
bull Reduced VOC deficit bull Large grain growth caused by GeSe2 liquid phase
Ge incorporated CZTSe (CZTGSe) CZTGSe
07 08 09 10 11 12 13 14 15 160
2
4
6
8
10
(ahυ
)2 times 1
08 ((eV
cm)2 )
Energy (eV)
Ge(Sn+Ge) Ge=000 Ge=028 Ge=051 Ge=064 Ge=079 Ge=100
1 μm
Cell Eff ()
VOC (V)
JSC (mAcm2)
FF ()
Eg (eV) Eg q-VOC
CZTGSSe Perdue Univ (2013) 1 940 0460 319 638 119 0730
CZTGSe AIST (2015) 2 1003 0543 295 627 119 0647
CZTSe IREC(2015) 3 1060 0473 343 651 103 0550
CZTGSe Univ of Washington (2016) 4 1100 0583 336 559 130 0717
I-V Results of Ge incorporated Cells
4
1 C J Hages et al Progress in Photovoltaics Research and Applications 23 (3) 376-384 (2013) 2 S Kim et al Solar Energy Materials and Solar Cells 144 488-492 (2016) 3 S Giraldo et al Advanced Energy Materials 5 (21) (2015) 4 A D Collord and H W Hillhouse Chemistry of Materials 28 (7) 2067-2073 (2016)
5
Experimental Procedure
SLG Mo
CZTGSe CdS
i-ZnO AZO
Al
As grown CZTGSe deposited by co-evaporation method Composition Control
Annealing using two zone furnace Grain Growth
Co-evaporation Annealing
CZTGSe solar cell structure
Ge
SLG Mo
Heater 200
Sample Pellets
Internal gases flow
00 01 02 03 04 050
10
20
30
J (m
Ac
m2 )
V (V)
Eff VOC JSC FF 12322 0527 32157 0727
400 600 800 1000 120000
02
04
06
08
10
EQ
E (
)
Wavelength (nm)
09 10 11 12 1300
02
04
06
08
10
[E ln
(1-E
QE
)]2
Energy (eV)
Eg=11eV
New efficiency of Ge incorporated kesterite solar cell
bull The highest efficiency of Ge incorporated kesterite solar cell greater than 12
6
7
Device parameters
Cell Eff ()
VOC (V)
JSC (mAcm2) FF Rs
(Ωcm2) Rsh
(Ωcm2) A J0 (A cm2)
Eg (eV) Egq-VOC
CZTSSe IBM (2013) 1260 0513 352 0698 072 621 145 70E-8 113 0617
CZTGSe AIST (2015) 1003 0543 295 0627 020 694 249 63E-6 119 0647
CZTGSe AIST (2016) 1232 0527 322 0727 036 1111 147 36E-8 111 0583
bull Highly improved fill factor over 07 bull Reduced device parameters ndash A Jo and VOC deficit rarr Improved junction quality and reduced carrier recombination in SCR
05 10 15 20 25 30
0
2
4
6
8
10
12 Efficiency FF
ZnIVE
ffici
ency
()
02
03
04
05
06
07
08
FF
Atomic ratio of CZTGSe thin films (EPMA)
bull Efficiency shows similar tendency with FF bull Optimized surface conditions are observed at CuZn=19 and ZnIV=12
04 06 08 10 12 14 16 18 20
2
4
6
8
10
12 Efficiency FF
CuZn
Effic
ienc
y (
)
030
035
040
045
050
055
060
065
070
075
FF
Surface composition ~ 120 nm
8
0 10 20 30 40 501
10
100
1000
10000
PL
Inte
nsity
(cou
nts)
Time (ns)
Decay curve Fit
τ2 = 56 ns
Lifetime measurement by TRPL Cell Eff () Lifetime (ns)
CZTSSe IBM (2013) 1260 67
CZTGSe AIST (2015) 1003 25
CZTGSe AIST (2016) 1232 56
09 10 11 12 13
PL In
tens
ity (a
rb u
nits
)
Energy (eV)
Eg = 11 eVEgopt = 108 eV bull Improved carrier life time bull PL peak is closed to the
band edge position (asymp003) ndash it may be beneficial effect in reducing VOC deficit
9
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
Cell Eff ()
VOC (V)
JSC (mAcm2)
FF ()
Eg (eV) Eg q-VOC
CZTGSSe Perdue Univ (2013) 1 940 0460 319 638 119 0730
CZTGSe AIST (2015) 2 1003 0543 295 627 119 0647
CZTSe IREC(2015) 3 1060 0473 343 651 103 0550
CZTGSe Univ of Washington (2016) 4 1100 0583 336 559 130 0717
I-V Results of Ge incorporated Cells
4
1 C J Hages et al Progress in Photovoltaics Research and Applications 23 (3) 376-384 (2013) 2 S Kim et al Solar Energy Materials and Solar Cells 144 488-492 (2016) 3 S Giraldo et al Advanced Energy Materials 5 (21) (2015) 4 A D Collord and H W Hillhouse Chemistry of Materials 28 (7) 2067-2073 (2016)
5
Experimental Procedure
SLG Mo
CZTGSe CdS
i-ZnO AZO
Al
As grown CZTGSe deposited by co-evaporation method Composition Control
Annealing using two zone furnace Grain Growth
Co-evaporation Annealing
CZTGSe solar cell structure
Ge
SLG Mo
Heater 200
Sample Pellets
Internal gases flow
00 01 02 03 04 050
10
20
30
J (m
Ac
m2 )
V (V)
Eff VOC JSC FF 12322 0527 32157 0727
400 600 800 1000 120000
02
04
06
08
10
EQ
E (
)
Wavelength (nm)
09 10 11 12 1300
02
04
06
08
10
[E ln
(1-E
QE
)]2
Energy (eV)
Eg=11eV
New efficiency of Ge incorporated kesterite solar cell
bull The highest efficiency of Ge incorporated kesterite solar cell greater than 12
6
7
Device parameters
Cell Eff ()
VOC (V)
JSC (mAcm2) FF Rs
(Ωcm2) Rsh
(Ωcm2) A J0 (A cm2)
Eg (eV) Egq-VOC
CZTSSe IBM (2013) 1260 0513 352 0698 072 621 145 70E-8 113 0617
CZTGSe AIST (2015) 1003 0543 295 0627 020 694 249 63E-6 119 0647
CZTGSe AIST (2016) 1232 0527 322 0727 036 1111 147 36E-8 111 0583
bull Highly improved fill factor over 07 bull Reduced device parameters ndash A Jo and VOC deficit rarr Improved junction quality and reduced carrier recombination in SCR
05 10 15 20 25 30
0
2
4
6
8
10
12 Efficiency FF
ZnIVE
ffici
ency
()
02
03
04
05
06
07
08
FF
Atomic ratio of CZTGSe thin films (EPMA)
bull Efficiency shows similar tendency with FF bull Optimized surface conditions are observed at CuZn=19 and ZnIV=12
04 06 08 10 12 14 16 18 20
2
4
6
8
10
12 Efficiency FF
CuZn
Effic
ienc
y (
)
030
035
040
045
050
055
060
065
070
075
FF
Surface composition ~ 120 nm
8
0 10 20 30 40 501
10
100
1000
10000
PL
Inte
nsity
(cou
nts)
Time (ns)
Decay curve Fit
τ2 = 56 ns
Lifetime measurement by TRPL Cell Eff () Lifetime (ns)
CZTSSe IBM (2013) 1260 67
CZTGSe AIST (2015) 1003 25
CZTGSe AIST (2016) 1232 56
09 10 11 12 13
PL In
tens
ity (a
rb u
nits
)
Energy (eV)
Eg = 11 eVEgopt = 108 eV bull Improved carrier life time bull PL peak is closed to the
band edge position (asymp003) ndash it may be beneficial effect in reducing VOC deficit
9
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
5
Experimental Procedure
SLG Mo
CZTGSe CdS
i-ZnO AZO
Al
As grown CZTGSe deposited by co-evaporation method Composition Control
Annealing using two zone furnace Grain Growth
Co-evaporation Annealing
CZTGSe solar cell structure
Ge
SLG Mo
Heater 200
Sample Pellets
Internal gases flow
00 01 02 03 04 050
10
20
30
J (m
Ac
m2 )
V (V)
Eff VOC JSC FF 12322 0527 32157 0727
400 600 800 1000 120000
02
04
06
08
10
EQ
E (
)
Wavelength (nm)
09 10 11 12 1300
02
04
06
08
10
[E ln
(1-E
QE
)]2
Energy (eV)
Eg=11eV
New efficiency of Ge incorporated kesterite solar cell
bull The highest efficiency of Ge incorporated kesterite solar cell greater than 12
6
7
Device parameters
Cell Eff ()
VOC (V)
JSC (mAcm2) FF Rs
(Ωcm2) Rsh
(Ωcm2) A J0 (A cm2)
Eg (eV) Egq-VOC
CZTSSe IBM (2013) 1260 0513 352 0698 072 621 145 70E-8 113 0617
CZTGSe AIST (2015) 1003 0543 295 0627 020 694 249 63E-6 119 0647
CZTGSe AIST (2016) 1232 0527 322 0727 036 1111 147 36E-8 111 0583
bull Highly improved fill factor over 07 bull Reduced device parameters ndash A Jo and VOC deficit rarr Improved junction quality and reduced carrier recombination in SCR
05 10 15 20 25 30
0
2
4
6
8
10
12 Efficiency FF
ZnIVE
ffici
ency
()
02
03
04
05
06
07
08
FF
Atomic ratio of CZTGSe thin films (EPMA)
bull Efficiency shows similar tendency with FF bull Optimized surface conditions are observed at CuZn=19 and ZnIV=12
04 06 08 10 12 14 16 18 20
2
4
6
8
10
12 Efficiency FF
CuZn
Effic
ienc
y (
)
030
035
040
045
050
055
060
065
070
075
FF
Surface composition ~ 120 nm
8
0 10 20 30 40 501
10
100
1000
10000
PL
Inte
nsity
(cou
nts)
Time (ns)
Decay curve Fit
τ2 = 56 ns
Lifetime measurement by TRPL Cell Eff () Lifetime (ns)
CZTSSe IBM (2013) 1260 67
CZTGSe AIST (2015) 1003 25
CZTGSe AIST (2016) 1232 56
09 10 11 12 13
PL In
tens
ity (a
rb u
nits
)
Energy (eV)
Eg = 11 eVEgopt = 108 eV bull Improved carrier life time bull PL peak is closed to the
band edge position (asymp003) ndash it may be beneficial effect in reducing VOC deficit
9
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
00 01 02 03 04 050
10
20
30
J (m
Ac
m2 )
V (V)
Eff VOC JSC FF 12322 0527 32157 0727
400 600 800 1000 120000
02
04
06
08
10
EQ
E (
)
Wavelength (nm)
09 10 11 12 1300
02
04
06
08
10
[E ln
(1-E
QE
)]2
Energy (eV)
Eg=11eV
New efficiency of Ge incorporated kesterite solar cell
bull The highest efficiency of Ge incorporated kesterite solar cell greater than 12
6
7
Device parameters
Cell Eff ()
VOC (V)
JSC (mAcm2) FF Rs
(Ωcm2) Rsh
(Ωcm2) A J0 (A cm2)
Eg (eV) Egq-VOC
CZTSSe IBM (2013) 1260 0513 352 0698 072 621 145 70E-8 113 0617
CZTGSe AIST (2015) 1003 0543 295 0627 020 694 249 63E-6 119 0647
CZTGSe AIST (2016) 1232 0527 322 0727 036 1111 147 36E-8 111 0583
bull Highly improved fill factor over 07 bull Reduced device parameters ndash A Jo and VOC deficit rarr Improved junction quality and reduced carrier recombination in SCR
05 10 15 20 25 30
0
2
4
6
8
10
12 Efficiency FF
ZnIVE
ffici
ency
()
02
03
04
05
06
07
08
FF
Atomic ratio of CZTGSe thin films (EPMA)
bull Efficiency shows similar tendency with FF bull Optimized surface conditions are observed at CuZn=19 and ZnIV=12
04 06 08 10 12 14 16 18 20
2
4
6
8
10
12 Efficiency FF
CuZn
Effic
ienc
y (
)
030
035
040
045
050
055
060
065
070
075
FF
Surface composition ~ 120 nm
8
0 10 20 30 40 501
10
100
1000
10000
PL
Inte
nsity
(cou
nts)
Time (ns)
Decay curve Fit
τ2 = 56 ns
Lifetime measurement by TRPL Cell Eff () Lifetime (ns)
CZTSSe IBM (2013) 1260 67
CZTGSe AIST (2015) 1003 25
CZTGSe AIST (2016) 1232 56
09 10 11 12 13
PL In
tens
ity (a
rb u
nits
)
Energy (eV)
Eg = 11 eVEgopt = 108 eV bull Improved carrier life time bull PL peak is closed to the
band edge position (asymp003) ndash it may be beneficial effect in reducing VOC deficit
9
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
7
Device parameters
Cell Eff ()
VOC (V)
JSC (mAcm2) FF Rs
(Ωcm2) Rsh
(Ωcm2) A J0 (A cm2)
Eg (eV) Egq-VOC
CZTSSe IBM (2013) 1260 0513 352 0698 072 621 145 70E-8 113 0617
CZTGSe AIST (2015) 1003 0543 295 0627 020 694 249 63E-6 119 0647
CZTGSe AIST (2016) 1232 0527 322 0727 036 1111 147 36E-8 111 0583
bull Highly improved fill factor over 07 bull Reduced device parameters ndash A Jo and VOC deficit rarr Improved junction quality and reduced carrier recombination in SCR
05 10 15 20 25 30
0
2
4
6
8
10
12 Efficiency FF
ZnIVE
ffici
ency
()
02
03
04
05
06
07
08
FF
Atomic ratio of CZTGSe thin films (EPMA)
bull Efficiency shows similar tendency with FF bull Optimized surface conditions are observed at CuZn=19 and ZnIV=12
04 06 08 10 12 14 16 18 20
2
4
6
8
10
12 Efficiency FF
CuZn
Effic
ienc
y (
)
030
035
040
045
050
055
060
065
070
075
FF
Surface composition ~ 120 nm
8
0 10 20 30 40 501
10
100
1000
10000
PL
Inte
nsity
(cou
nts)
Time (ns)
Decay curve Fit
τ2 = 56 ns
Lifetime measurement by TRPL Cell Eff () Lifetime (ns)
CZTSSe IBM (2013) 1260 67
CZTGSe AIST (2015) 1003 25
CZTGSe AIST (2016) 1232 56
09 10 11 12 13
PL In
tens
ity (a
rb u
nits
)
Energy (eV)
Eg = 11 eVEgopt = 108 eV bull Improved carrier life time bull PL peak is closed to the
band edge position (asymp003) ndash it may be beneficial effect in reducing VOC deficit
9
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
05 10 15 20 25 30
0
2
4
6
8
10
12 Efficiency FF
ZnIVE
ffici
ency
()
02
03
04
05
06
07
08
FF
Atomic ratio of CZTGSe thin films (EPMA)
bull Efficiency shows similar tendency with FF bull Optimized surface conditions are observed at CuZn=19 and ZnIV=12
04 06 08 10 12 14 16 18 20
2
4
6
8
10
12 Efficiency FF
CuZn
Effic
ienc
y (
)
030
035
040
045
050
055
060
065
070
075
FF
Surface composition ~ 120 nm
8
0 10 20 30 40 501
10
100
1000
10000
PL
Inte
nsity
(cou
nts)
Time (ns)
Decay curve Fit
τ2 = 56 ns
Lifetime measurement by TRPL Cell Eff () Lifetime (ns)
CZTSSe IBM (2013) 1260 67
CZTGSe AIST (2015) 1003 25
CZTGSe AIST (2016) 1232 56
09 10 11 12 13
PL In
tens
ity (a
rb u
nits
)
Energy (eV)
Eg = 11 eVEgopt = 108 eV bull Improved carrier life time bull PL peak is closed to the
band edge position (asymp003) ndash it may be beneficial effect in reducing VOC deficit
9
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
0 10 20 30 40 501
10
100
1000
10000
PL
Inte
nsity
(cou
nts)
Time (ns)
Decay curve Fit
τ2 = 56 ns
Lifetime measurement by TRPL Cell Eff () Lifetime (ns)
CZTSSe IBM (2013) 1260 67
CZTGSe AIST (2015) 1003 25
CZTGSe AIST (2016) 1232 56
09 10 11 12 13
PL In
tens
ity (a
rb u
nits
)
Energy (eV)
Eg = 11 eVEgopt = 108 eV bull Improved carrier life time bull PL peak is closed to the
band edge position (asymp003) ndash it may be beneficial effect in reducing VOC deficit
9
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
Summary
bull We demonstrate new results of Ge incorporated kesterite
thin-film solar cell
ndash High efficiency greater than 12
ndash Large improvement in FF over 07
ndash Improved junction quality and reduced carrier recombination in SCR
ndash A J0 and VOC deficit
ndash Increased carrier life time
10
Thank you for your attention
Thank you for your attention
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