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Proceedings Paper

Improved photovoltaic properties of ZnTeO-based intermediate band solar cells
Author(s): Tooru Tanaka; Katsuhiko Saito; Qixin Guo; Kin Man Yu; Wladek Walukiewicz
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Paper Abstract

Highly mismatched ZnTe1-xOx (ZnTeO) alloy is one of the potential candidates for an absorber material in a bulk intermediate band solar cell (IBSC) because a narrow, O-derived intermediate band IB (E-) is formed well below the conduction band CB (E+) edge of the ZnTe. We have previously demonstrated the generation of photocurrent induced by two-step photon absorption (TSPA) in ZnTeO IBSCs using n-ZnO window layer. However, because of the large conduction band offset (CBO) between ZnTe and ZnO, only a small open circuit voltage (Voc) was observed in this structure. Here, we report our recent progress on the development of ZnTeO IBSCs with n-ZnS window layer. ZnS has a large direct band gap of 3.7 eV with an electron affinity of 3.9 eV that can realize a smaller CBO with ZnTe. We have grown n-type ZnS thin films on ZnTe substrates by molecular beam epitaxy (MBE), and demonstrated ZnTe solar cells and ZnTeO IBSCs using n-ZnS window layer with an improved VOC. Especially, a n-ZnS/i-ZnTe/p-ZnTe solar cell showed an improved Voc of 0.77 V, a large short-circuit current density of 6.7 mA/cm2 with a fill factor of 0.60, yielding the power conversion efficiency of 3.1 %, under 1 sun illumination.

Paper Details

Date Published: 16 February 2018
PDF: 6 pages
Proc. SPIE 10527, Physics, Simulation, and Photonic Engineering of Photovoltaic Devices VII, 105270P (16 February 2018); doi: 10.1117/12.2292911
Show Author Affiliations
Tooru Tanaka, Saga Univ. (Japan)
Katsuhiko Saito, Saga Univ. (Japan)
Qixin Guo, Saga Univ. (Japan)
Kin Man Yu, City Univ. of Hong Kong (Hong Kong, China)
Wladek Walukiewicz, Lawrence Berkeley National Lab. (United States)
Univ. of California, Berkeley (United States)

Published in SPIE Proceedings Vol. 10527:
Physics, Simulation, and Photonic Engineering of Photovoltaic Devices VII
Alexandre Freundlich; Laurent Lombez; Masakazu Sugiyama, Editor(s)

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