This study investigates the charge separation mechanism at the interface between Sb2S3 and CuSCN layers in solid-state solar cells using transient absorption spectroscopy. The researchers analyzed films with and without a hole conductor layer to determine the hole trapping rate in Sb2S3 and hole transfer rate at the interface. They found correspondence between the decay of photogenerated holes at 460 nm and growth of sulfide radicals at 560 nm, indicating hole trapping in Sb2S3. Comparison of films with and without CuSCN allowed calculation of the hole transfer rate from Sb2S3 to CuSCN. The study provides insight into the dynamics and limiting factors for performance of Sb2S3 solid

1. Trap and Transfer. Two-Step Hole
Injection Across the Sb2S3/CuSCN
Interface in Solid-State Solar Cells.
Jeffrey A. Christians, and Prashant V. Kamat
Radiation Laboratory, Department of Chemical & Biomolecular Engineering, Department & Chemistry and
Biochemistry, University of Notre Dame, Notre Dame, Indiana, 46556, United States.
DOI: 10.1021/nn403058f
®

2. • Provide broad spectral response (1.7 eV band gap)
• Promising power conversion efficiencies
Sb2S3 Photovoltaic Performance ®
JSC VOC FF η
12.4 mA cm-2 455 mV 0.59 3.3 %

3. Motivation ®
• Investigate the dynamics of the
charge separation mechanism
• Develop an understanding of the
limiting factors of performance
Sb2S3 + hν Sb2S3(h + e)
Sb2S3(h + e) Sb2S3 + heat
Sb2S3(h + e) + TiO2 Sb2S3(h) + TiO2(e)
Sb2S3(h) + CuSCN Sb2S3 + CuSCN(h)
(1)
(2)
(3)
(4)

4. Sb2S3 Films ®
• Investigate charge separation process using for films
A. TiO2/Sb2S3 (electron transfer)
B. TiO2/Sb2S3/CuSCN (electron and hole transfer)
C. SiO2/Sb2S3 (no charge transfer)
D. SiO2/Sb2S3/CuSCN (hole transfer)
• Planar film structure
− Allows for precise control of Sb2S3 layer thickness
− Minimizes absorption and scattering for spectroscopy

5. Transient Absorption ®
1. Broad sulfide radical
(trapped hole) induced
absorbance from 500 nm
– 750 nm
2. Bleaching of excitonic
peaks at 460 nm and 650
nm

6. • Fit 460 nm decay to
biexponential model
• Calculate hole
trapping (S−•
formation) rate
Hole Trapping in Sb2S3 ®
• Correspondence of 460 nm decay with 560 nm S−•
absorbance growth implies both signals due to hole
trapping

7. Transfer from Sb2S3 to CuSCN ®
• Compare average lifetime of S−• species with and
without hole conductor to obtain hole transfer
information
• Fit 560 nm decay to
biexponential model
• Calculate hole
transfer rate

8. Conclusions ®

9. Thank You ®
This research was supported
by the U.S. Department of
Energy
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Trap and Transfer. Two-Step Hole Injection
Across the Sb2S3/CuSCN Interface in Solid-
State Solar Cells.
Jeffrey A. Christians, and Prashant V. Kamat
Radiation Laboratory, Department of Chemical & Biomolecular Engineering, Department &
Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, 46556, United
States.
DOI: 10.1021/nn403058f