Fabrication of Cd-free CuInSe2 solar cells using wet processes

Abstract

CuInSe2 has become an attractive material for use in the production of thin-film solar cells. Recently, energy conversion efficiencies over 20% have been achieved by CuInSe2 solar cells created using vacuum processes. To reduce manufacturing costs, more recent efforts have focused on non-vacuum processes. In this study, we fabricated solar cells exclusively by wet processes. CuInSe2 absorption layers and In2S3 buffer layers were electrochemically or chemically deposited, and ZnO window layers were formed using solution-based chemical methods. The deposited CuInSe2 absorption layers were heat-treated to improve crystallinity. We deposited a Cd-free buffer layer of In2S3 using a chemical bath method on the CuInSe2 absorption layers, and then ZnO window layers were deposited by a solution-based process. With this system, we successfully fabricated CuInSe2 solar cells and obtained a cell efficiency of 2.38%.