Nanostructured Cu2ZnSnS4 thin films: influence of substrate temperature on structural, morphological, optical and electrical properties

Abstract

Photovoltaic Cu 2 ZnSnS 4 (CZTS) thin films have been deposited on the glass substrate by a simple and low-cost spray pyrolysis technique without sulfurization treatment in a toxic atmosphere. The influence of the substrate temperatures on the structural, compositional, morphological, optical and electrical properties of the CZTS films was investigated. The formation of kesterite structure in the films was confirmed using X-ray diffraction measurements. The improved crystallinity of the CZTS with a (112) orientation was observed with increasing the substrate temperature. The band gap of all films was found to be in the range from 1.44 to 1.56 eV which is close to the ideal band gap for the highest theoretical conversion efficiency of solar cell. AFM analysis revealed a smooth, compact and crack-free morphology. The electrical studies showed that all these samples had a p-type conductivity, and the free hole density and mobility increased with increasing the substrate temperature.