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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

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

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12

Thank you for your attention

• スライド番号 1
• Introduction ndash Kesterite solar cells
• スライド番号 3
• Ge incorporated CZTSe (CZTGSe)
• スライド番号 5
• Experimental Procedure
• スライド番号 7
• Device parameters
• スライド番号 9
• スライド番号 10
• スライド番号 11
• スライド番号 12