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Restraining the Band Fluctuation of CBD‐Zn(O,S) Layer: Modifying the Hetero‐Junction Interface for High Performance Cu 2 ZnSnSe 4 Solar Cells With Cd‐Free Buffer Layer
Author(s) -
Li Jianjun,
Liu Xiaoru,
Liu Wei,
Wu Li,
Ge Binghui,
Lin Shuping,
Gao Shoushuai,
Zhou Zhiqiang,
Liu Fangfang,
Sun Yun,
Ao Jianping,
Zhu Hongbing,
Mai Yaohua,
Zhang Yi
Publication year - 2017
Publication title -
solar rrl
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.544
H-Index - 37
ISSN - 2367-198X
DOI - 10.1002/solr.201700075
Subject(s) - kesterite , materials science , energy conversion efficiency , annealing (glass) , buffer (optical fiber) , layer (electronics) , solar cell , optoelectronics , chemical engineering , analytical chemistry (journal) , nanotechnology , chemistry , czts , metallurgy , chromatography , engineering , telecommunications , computer science
Zn(O,S) film is a promising low‐cost and environment‐friendly Cd‐free buffer layer for chalcopyrite and kesterite thin film solar cells. However, the devices with Zn(O,S) buffer layer usually suffer from poor interface performance, resulting in a much lower efficiency, especially for kesterite solar cells. Here, the band fluctuation caused by ZnO secondary phase in Zn(O,S) layer is identified as the main reason deteriorating the device performance. By a concentrated ammonium etching and subsequent soft annealing treatment, the detrimental ZnO and Zn(OH) 2 secondary phases are eliminated from the Zn(O,S) layer and the hetero‐junction performance is improved significantly. Consequently, the power conversion efficiency of the Zn(O,S)/CZTSe solar cells was improved from 1.17% to a favorable value of 7.2%. Temperature dependent J–V properties reveal a defect level assisted charge carrier transport mechanism across the Zn(O,S)/CZTSe interface. These encouraging results imply that Zn(O,S) buffer layer is a promising substitution for toxic CdS in future manufacturing of high performance thin film solar cells.