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ESI-1
Electronic supplementary information (ESI) for
Achieving Over 4% Efficiency for SnS/CdS Thin-Film Solar
Cells by Improving Heterojunction Interface Quality
Jae Yu Cho,a SeongYeon Kim,b Raju Nandi,a Junsung Jang,a Hee-Sun
Yun,c,d
Enkhjargal Enkhbayar,b Jin Hyeok Kim,a Doh-Kwon Lee,c,d
Choong-Heui Chung,e
JunHo Kim,b,* and Jaeyeong Heoa,*
aDepartment of Materials Science and Engineering, and
Optoelectronics Convergence Research Center, Chonnam National
University, Gwangju 61186, Republic of KoreabDepartment of Physics,
Incheon National University, Incheon 22012, Republic of Korea
cPhoto-electronic Hybrids Research Center, Korea Institute of
Science and Technology (KIST), Seoul 02792, Republic of Korea
dDivision of Nano and Information Technology, KIST School Korea
University of Science and Technology, Seoul 02792, Republic of
Korea
eDepartment of Materials Science and Engineering, Hanbat
National University, Daejeon 34158, Republic of Korea
* Corresponding authorE-mail: [email protected] (Prof. J.
Kim)E-mail: [email protected] (Prof. J. Heo)
Electronic Supplementary Material (ESI) for Journal of Materials
Chemistry A.This journal is © The Royal Society of Chemistry
2020
mailto:[email protected]:[email protected]
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ESI-2
2.0 2.5 3.0 3.5 4.0
(h
)2
Energy (eV)
RT (3.49 eV) 100 oC (3.63 eV) 200 oC (3.76 eV) 300 oC (3.71 eV)
400 oC (3.65 eV)
0 100 200 300 40010-4
10-3
10-2
Deposition temperature (oC)
Resistivity (.cm)
0.0
2.0x1020
4.0x1020
6.0x1020
8.0x1020
1.0x1021
Carrier concentration (cm-3)
5
10
15
20
25
Carrier mobility (cm2.V-1.s-1)
300 400 500 600 700 8000
20
40
60
80
100 T
rans
mitt
ance
(%)
Wavelength (nm)
RT (87.8%) 100 oC (89.9%) 200 oC (91.0%) 300 oC (93.2%) 400 oC
(93.4%)
(a) (b) (c)
Fig. S1. (a) Transmittance spectra, (b) bandgap extraction, and
(c) electrical properties of the AZO films
grown at different temperatures from room temperature to 400
°C.
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ESI-3
0.0 0.1 0.2 0.3 0.40
5
10
15
20
25Cu
rrent
den
sity
(mA
cm2
)
Voltage (V)
(a)
0.0 0.1 0.2 0.3 0.40
5
10
15
20
25
Curre
nt d
ensit
y (m
A cm
2)
Voltage (V)
(b)
0.0 0.1 0.2 0.3 0.40
5
10
15
20
25
Curre
nt d
ensit
y (m
A cm
2)
Voltage (V)
(c)
0.0 0.1 0.2 0.3 0.40
5
10
15
20
25
Curre
nt d
ensit
y (m
A cm
2)
Voltage (V)
(d)
0.0 0.1 0.2 0.3 0.40
5
10
15
20
25
Curre
nt d
ensit
y (m
A cm
2)
Voltage (V)
(e)
Fig. S2. J–V characteristics of the SnS/CdS TFSCs at different
AZO film deposition temperatures of (a)
150 °C, (b) 200 °C, (c) 250 °C, (d) 300 °C, and (e) 350 °C.
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ESI-4
Mo
SnS
i-ZnO/AZOCdS
1 m Mo
SnS
i-ZnO/AZOCdS
1 m
(a) (b)
Fig. S3. Cross-sectional SEM images of the SnS/CdS TFSCs with
AZO films deposited at (a) 150 °C and
(b) 300 °C.
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ESI-5
0 500 1000 1500103
104
105
Inte
nsity
(c/s
)
Time (s)
Sn (250 oC) S (250 oC) Cd (250 oC) Sn (350 oC) S (350 oC) Cd
(350 oC)
103
104
105
Inte
nsity
(c/s
)
Time (arb. unit)
Sn (250 oC) S (250 oC) Cd (250 oC) Sn (350 oC) S (350 oC) Cd
(350 oC)
0 500 1000 1500 2000101
102
103
104
105
106
Zn Mo Cd Sn
Inte
nsity
(c/s
)
Time (s)
O Na Al S
0 500 1000 1500 2000101
102
103
104
105
106
Zn Mo Cd Sn
Inte
nsity
(c/s
)
Time (s)
O Na Al S
(a)
(b)
(c)
(d)
SSn
Cd
Fig. S4. Full SIMS depth profiles of the TFSCs with AZO
deposited at (a) 250 and (b) 350 oC without Al
top contact. (c) The selected profiles for Sn, S, and Cd ions.
(d) The shifted profiles for matching the
initial detection of S, Sn, and Cd signals to evaluate the Cd
diffusion into SnS absorbers. Slight Cd
diffusion into SnS absorber is noted for the 350 oC device.
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ESI-6
50
60
70
80
90
100
110
54.7
65.3
80.1
101.397.3
350300250200
Effi
cien
cy re
tent
ion
(%)
AZO deposition temperature (oC)1500.0 0.1 0.2 0.3 0.4
0
5
10
15
20
25
C
urre
nt d
ensi
ty (m
A c
m-2)
Voltage (V)
150 oC 200 oC 250 oC 300 oC 350 oC
2018.05. 2020.04.
(a) (b)
Fig. S5. (a) J–V characteristics and (b) the efficiency
retention of SnS/CdS TFSCs at various AZO film
deposition temperatures of 150–350 °C. To test the long-term
stability of the TFSCs, the device
performance was measured again after almost two years.
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0 50 100 150 200 250 3000.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0 V o
c (V)
Temperature (K)
AZO deposition temperature 150 C 200 C 250 C 300 C 350 C
150 200 250 300 3500.5
0.6
0.7
0.8
0.9
EA (e
V)
AZO deposition temperature (C)
(a) (b)
Fig. S6. (a) Temperature dependence of Voc for TFSCs with
various AZO deposition temperatures at 150
to 350 °C. (b) The extracted activation energy as a function of
AZO deposition temperature.
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5 m 5 m
(a) (b)
Fig. S7. Plan-view SEM images of the SnS absorbers annealed in
(a) vacuum condition (~10-2 Torr), and
(b) 20 Torr in Ar ambient, respectively. Partial evaporation of
SnS surface is observed for (a) vacuum
condition.
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300 400 500 600 700 8000
20
40
60
80
100
Tran
smitt
ance
(%)
Wavelength (nm)
2 3 4
(h
)2 Energy (eV)
3.58 eV
Fig. S8. Transmittance spectrum of the AZO layer grown in a
home-made sputter at room temperature;
the inset shows the bandgap extraction plot (Eg = 3.58 eV). The
average transmittance for 400 – 700 nm
was 89.0%. The film thickness was ~380 nm and the sheet
resistance was 28 ohm/sq. with resistivity of
1.066 × 10-3 ohm cm.
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0.0 0.1 0.2 0.3 0.40
5
10
15
20
25
Cur
rent
den
sity
(mA
cm
-2)
Voltage (V)
(a)Best cellVoc = 0.249 VJsc = 15.6 mA cm-2FF = 0.524 =
2.04%
0.0 0.1 0.2 0.3 0.40
5
10
15
20
25
Cur
rent
den
sity
(mA
cm
-2)
Voltage (V)
(b)Best cellVoc = 0.217 VJsc = 14.5 mA cm-2FF = 0.512 =
1.61%
0.0 0.1 0.2 0.3 0.40
5
10
15
20
25
Cur
rent
den
sity
(mA
cm
-2)
Voltage (V)
(c)
Best cellVoc = 0.332 VJsc = 22.1 mA cm-2FF = 0.575 = 4.20%
Fig. S9. J–V characteristics of the TFSCs with (a) as-deposited
SnS/CdS without any junction annealing,
(b) annealed SnS at 300 °C in Ar ambient and as-deposited CdS
without any junction annealing, and (c)
as-deposited SnS/CdS with additional junction annealing at 300
°C in Ar ambient. Here, the annealing
duration and pressure was fixed at 1 h and 20 Torr,
respectively, and in total, six cells were fabricated.
The highest efficiencies achieved for these devices were 2.04%,
1.61%, and 4.20%, respectively.
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ESI-11
(a) (b)
Fig. S10. (a) J–V and (b) EQE certifications of the champion
cell ( = 4.225%) measured at KIER in
Korea.
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ESI-12
200 400 600 800 1000 1200 14000
20
40
60
80
100
T,R,
A (%
)
Wavelength (nm)
T R A
Glass/FTO
200 400 600 800 1000 1200 14000
20
40
60
80
100Glass/FTO/CdS
T,R,
A (%
)
Wavelength (nm)
T R A
200 400 600 800 1000 1200 14000
20
40
60
80
100
T,R,
A (%
)
Wavelength (nm)
T R A
Glass/i-ZnO/AZO
200 400 600 800 1000 1200 14000
20
40
60
80
100R
(%)
Wavelength (nm)
Glass/Mo/SnS/CdS/i-ZnO/AZO(a) (b)
(c) (d)
Fig. S11. (a) Reflectance spectrum of the full device without a
top metal grid. Transmittance, reflectance,
and absorbance spectra for (b) glass/i-ZnO/AZO, (c) glass/FTO,
and (d) glass/FTO/CdS. Figure (b) was
used for calculating absorption in the transparent electrodes
(i-ZnO/AZO). Figure (c) and (d) were used
for calculating absorption in CdS buffer layer.
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ESI-13
Table S1. Electrical properties of AZO thin films grown at
different temperatures.
AZO filmdeposition
Temperature (°C)
RT 100 200 300 400
Thickness(nm)
494 491 406 435 405
Rsheet
(Ω/sq.)
55.1 16.0 7.8 11.7 21.9
Resistivity(Ω cm)
2.72 × 10-3 7.86 × 10-4 3.17 × 10-4 5.09 × 10-4 8.87 × 10-4
Carrier concentration
(cm-3)2.2 × 1020 5.4 × 1020 9.6 × 1020 6.2 × 1020 6.4 × 1020
Mobility(cm2 V-1s-1)
9.8 14.5 20.6 19.5 10.9
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Table S2. Simulated diode parameters for SnS/CdS TFSCs at
various AZO film deposition temperatures
from 150 °C to 350 °C.
AZO film deposition temperature
(°C)
Gsh(mS cm-2)
Rs(Ω cm2)
A J0(mA cm-2)
150 2.430 0.491 1.228 2.23 × 10-2
200 2.795 0.534 1.215 1.27 × 10-2
250 2.214 0.441 1.424 1.66 × 10-3
300 1.073 0.707 1.244 3.63 × 10-3
350 0.289 0.710 1.241 2.88 × 10-3