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Title: Reduced defect density at the CZTSSe/CdS interface by atomic layer deposition of Al 2O 3

The greatest challenge for improving the power conversion efficiency of Cu 2ZnSn(S,Se) 4 (CZTSSe)/CdS/ZnO thin film solar cells is increasing the open circuit voltage (V OC). Probable leading causes of the V OC deficit in state-of-the-art CZTSSe devices have been identified as bulk recombination, band tails, and the intertwined effects of CZTSSe/CdS band offset, interface defects, and interface recombination. Here, in this work, we demonstrate the modification of the CZTSSe absorber/CdS buffer interface following the deposition of 1 nm-thick Al 2O 3 layers by atomic layer deposition (ALD) near room temperature. Capacitance-voltage profiling and quantum efficiency measurements reveal that ALD-Al 2O 3 interface modification reduces the density of acceptor-like states at the heterojunction resulting in reduced interface recombination and wider depletion width. Indications of increased V OC resulting from the modification of the heterojunction interface as a result of ALD-Al 2O 3 treatment are presented. These results, while not conclusive for application to state-of-the-art high efficiency CZTSSe devices, suggest the need for further studies as it is probable that interface recombination contributes to reduced V OC even in such devices.
Authors:
 [1] ;  [2] ;  [3]
  1. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Electrical and Computer Engineering
  2. AQT Solar, Inc., Sunnyvale, CA (United States)
  3. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Electrical and Computer Engineering, and Dept. of Materials Science and Engineering
Publication Date:
Grant/Contract Number:
SC0001630
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 119; Journal Issue: 19; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Utah, Salt Lake City, UT (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1471099
Alternate Identifier(s):
OSTI ID: 1253658

Erkan, Mehmet Eray, Chawla, Vardaan, and Scarpulla, Michael A. Reduced defect density at the CZTSSe/CdS interface by atomic layer deposition of Al2O3. United States: N. p., Web. doi:10.1063/1.4948947.
Erkan, Mehmet Eray, Chawla, Vardaan, & Scarpulla, Michael A. Reduced defect density at the CZTSSe/CdS interface by atomic layer deposition of Al2O3. United States. doi:10.1063/1.4948947.
Erkan, Mehmet Eray, Chawla, Vardaan, and Scarpulla, Michael A. 2016. "Reduced defect density at the CZTSSe/CdS interface by atomic layer deposition of Al2O3". United States. doi:10.1063/1.4948947. https://www.osti.gov/servlets/purl/1471099.
@article{osti_1471099,
title = {Reduced defect density at the CZTSSe/CdS interface by atomic layer deposition of Al2O3},
author = {Erkan, Mehmet Eray and Chawla, Vardaan and Scarpulla, Michael A.},
abstractNote = {The greatest challenge for improving the power conversion efficiency of Cu2ZnSn(S,Se)4 (CZTSSe)/CdS/ZnO thin film solar cells is increasing the open circuit voltage (VOC). Probable leading causes of the VOC deficit in state-of-the-art CZTSSe devices have been identified as bulk recombination, band tails, and the intertwined effects of CZTSSe/CdS band offset, interface defects, and interface recombination. Here, in this work, we demonstrate the modification of the CZTSSe absorber/CdS buffer interface following the deposition of 1 nm-thick Al2O3 layers by atomic layer deposition (ALD) near room temperature. Capacitance-voltage profiling and quantum efficiency measurements reveal that ALD-Al2O3 interface modification reduces the density of acceptor-like states at the heterojunction resulting in reduced interface recombination and wider depletion width. Indications of increased VOC resulting from the modification of the heterojunction interface as a result of ALD-Al2O3 treatment are presented. These results, while not conclusive for application to state-of-the-art high efficiency CZTSSe devices, suggest the need for further studies as it is probable that interface recombination contributes to reduced VOC even in such devices.},
doi = {10.1063/1.4948947},
journal = {Journal of Applied Physics},
number = 19,
volume = 119,
place = {United States},
year = {2016},
month = {5}
}