Impacts of selenization time on Cu2ZnSnSe4 thin films prepared from an ethanolamine-dimethyl formamide based precursor solution

Abstract

Most precursor solutions for preparing Cu2ZnSn(S,Se)4 thin films use sulfur containing groups to complex metal ions. However, solutions with sulfur containing groups are always toxic and harmful gases, such as H2S and SOx, will be released when drying precursor films. Based on the excellent chelating ability of ethanolamine, a stable molecular precursor solution without using sulfur based complexing agent was successfully developed. Cu-Sn alloy phase is formed in the precursor film, which makes the phase evolution of the absorber during selenization similar to that of Cu2ZnSnSe4 film grown from metallic precursor. Impacts of selenization time on compositional, morphological and photovoltaic properties of the Cu2ZnSnSe4 film were studied. Finally, a Cu2ZnSnSe4 solar cell with conversion efficiency of 7.53% was obtained by using the ethanolamine-dimethyl formamide based solution.