Improving the crystallization and carrier recombination of Cu2ZnSnS4 thin film deposited on Mo-coated soda-lime glass by extra sodium doping through solution process

Abstract In this paper an easy and mild solution-processed method is introduced to prepare extra sodium (Na) doped Cu 2 ZnSnS 4 (CZTS) films on Mo-coated soda-lime glasses. Through this method, the Na-doping concentration can be adjusted at the range from 3.9% to 5.4% continuously. By extra Na doping through solution process, the grain size of CZTS particles was enlarged apparently without introducing any impurity phase. More excitingly, the photoluminescence (PL) spectrum indicates that high Na-doping concentration has the strong suppression ability on the band-gap recombination of CZTS films. The carrier lifetime is promoted from 2.1 ns to 2.83 ns. CZTS thin film solar cell with 4.8% Na-doping concentration shows the best performance.