Effect of Ge & ZnO inter-layer on the properties of CZTSSe absorber layer

Abstract

The use of intermediate layer between Mo and CZTSSe highly affects the properties of Cu 2 ZnSn(S x Se 1-x ) 4 (CZTSSe) absorber layer. The goal of the present work is to get a deeper insight into the beneficial effects of incorporation of an inter-layer between Mo and CZTSSe on absorber layer properties. In this work Ge and ZnO thin layer deposited on the different Mo coated Soda lime glass (SLG) substrates, then a thin layer of CZTS were printed by Doctor blade method, followed by Selenium deposition by thermal evaporation. Films were annealed at 450 °C for 20 min and its structural, optical and electrical properties were studied. The main purpose of this work is to study the variation in the properties of the absorber layer with and without an inter-layer. The crystallinity, conductivity, grain size and mobility of the film improves with Ge as an intermediate layer as compared to Mo or Mo/ZnO. The band gap decreases for Ge intermediate layer and slightly increases with ZnO as an intermediate layer. The Germanium layered film enhances the grain growth and crystallinity of the film as compared to Mo and Zinc Oxide layered. The changes observed in the film properties with the incorporation of Ge and ZnO inter-layer is discussed in the present paper.