Realization and electrical characterization of thin film heterojunction for photovoltaic application.

Abstract

The present work deals with the deposition of CZTS thin films and related devices by a simple and cheap technique such as Spray Pyrolysis (SP). For this purpose, a set of CZTS thin film was prepared using various deposition conditions in order to optimize the deposition conditions allow us to prepare suitable films devoted to the photovoltaic applications. The studied deposition parameters were the substrate temperature, deposition time, and copper and zinc salt concentrations. The structural analysis shows that the obtained films are polycrystalline; they exhibit a tetragonal structure with a preferential orientation along (112). However, the structural properties and secondary phases were affected by the deposition conditions. From the optical and electrical characterization results, we inferred that the deposited films have suitable optoelectronic properties for the photovoltaic applications, since they present a good absorption in the visible range coupled with a higher conductivity. Finally; the fabricated CZTS heterojunction with various back contacts show a rectification behavior, the G-f characterization reveals the presence of interface state at CZTS/ZnS interface with a state density in the order of 1010 eV-1cm-2. The addition of ZnO intrinsic layer enhances the heterojunction device properties. Whereas, the solar cells based CZTS/CdS annealed at 450 °C under H2S gas show the best solar cell efficiency about 0.43 % and a current density equal 9.8 mA/cm2.