Trap and Transfer. Two-Step Hole
Injection Across the Sb2S3/CuSCN
Interface in Solid-State Solar Cells.
Jeffrey A. Christi...
• Provide broad spectral response (1.7 eV band gap)
• Promising power conversion efficiencies
Sb2S3 Photovoltaic Performan...
Motivation ®
• Investigate the dynamics of the
charge separation mechanism
• Develop an understanding of the
limiting fact...
Sb2S3 Films ®
• Investigate charge separation process using for films
A. TiO2/Sb2S3 (electron transfer)
B. TiO2/Sb2S3/CuSC...
Transient Absorption ®
1. Broad sulfide radical
(trapped hole) induced
absorbance from 500 nm
– 750 nm
2. Bleaching of exc...
• Fit 460 nm decay to
biexponential model
• Calculate hole
trapping (S−•
formation) rate
Hole Trapping in Sb2S3 ®
• Corres...
Transfer from Sb2S3 to CuSCN ®
• Compare average lifetime of S−• species with and
without hole conductor to obtain hole tr...
Conclusions ®
Thank You ®
This research was supported
by the U.S. Department of
Energy
Visit KamatLab.com for more research from our
gro...
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Trap and Transfer. Two-Step Hole Injection Across the Sb2S3/CuSCN Interface in Solid State Solar Cells.

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Trap and Transfer. Two-Step Hole Injection Across the Sb2S3/CuSCN Interface in Solid State Solar Cells. ACS Nano, 2013, ASAP.
DOI: 10.1021/nn403058f

In solid-state semiconductor-sensitized solar cells, commonly known as extremely thin absorber (ETA) or solid-state quantum dot sensitized solar cells (QDSCs), transfer of photogenerated holes from the absorber species to the p-type hole conductor plays a critical role in the charge separation process. Using Sb2S3 (absorber) and CuSCN (hole conductor), we have constructed ETA solar cells exhibiting a power conversion efficiency of 3.3%. The hole transfer from excited Sb2S3 into CuSCN, which limits the overall power conversion efficiency of these solar cells, is now independently studied using transient absorption spectroscopy. In the Sb2S3 absorber layer, photogenerated holes are rapidly localized on the sulfur atoms of the crystal lattice, forming a sulfide radical (S−•) species. This trapped hole is transferred from the Sb2S3 absorber to the CuSCN hole conductor with an exponential time constant of 1680 ps. This process was monitored through the spectroscopic signal seen for the S−• species in Sb2S3, providing direct evidence for the hole transfer dynamics in ETA solar cells. Elucidation of the hole transfer mechanism from Sb2S3 to CuSCN represents a significant step toward understanding charge separation in Sb2S3 solar cells, and provides insight into the design of new architectures for higher efficiency devices.

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Trap and Transfer. Two-Step Hole Injection Across the Sb2S3/CuSCN Interface in Solid State Solar Cells.

  1. 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. 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. 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. 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. 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. 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. 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. 8. Conclusions ®
  9. 9. Thank You ® This research was supported by the U.S. Department of Energy Visit KamatLab.com for more research from our group or find us on Facebook at 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

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