Development of Co-evaporated In2S3 Buffer Layer for Cu2ZnSnSe4 Thin Film Solar Cells

Abstract

In this work, we focus on the replacement of the commonly used but toxic Cd-based buffer layer by In2S3 thin films deposited by co-evaporation for application in Cu2ZnSnSe4 (CZTSe) solar cells. The impact of the deposition conditions of the buffer layer on the electrical behavior of CZTSe/In2S3 devices is first investigated. The best solar cell efficiencies were obtained for relatively thick In2S3 buffer layers (similar to 100 nm) deposited at low temperature (<100 degrees C). It is also observed that low [Cu]/([Zn]+[Sn]) ratio (CZT similar to 0.75) in the kesterite absorber leads to high efficiency for In-based buffered CZTSe solar cells, while the effect of the CZT ratio on CZTSe/CdS solar cell performances is not so clear. A conversion efficiency of 5.7 % on CZTSe/In2S3 thin film solar cell is achieved.