Insight into the role of selenization time for highly efficient Mn doped Cu2ZnSn(S,Se)4 thin film based solar cells

Abstract

In this study, manganese (Mn) doped Cu2ZnSn(S,Se)4 (CMZTSSe) absorption layer films were prepared using a sol–gel method followed by a selenization treatment in a selenium environment. In this paper, we discuss the impact of annealing time on the structure, morphology, and properties of CMZTSSe absorption layer films. The crystal quality of the CMZTSSe films increased, and the major Se occupied the position in CMZTSSe with the increase of the annealing time. When the annealing time was 15 min, a smooth and dense film was obtained. The band gap of CMZTSSe was adjusted between 1.19 and 1.09 eV by adjusting the post-annealing time. The influence mechanisms of the annealing time on the performance of a solar cell were investigated by systematically learning the variation in the shunt resistance (RSh) and series resistance (RS) with the microstructure of the CMZTSSe films selenized at different times. The results showed that the power conversion efficiency (PCE) initially increased and then decreased when the annealing time was increased from 10 to 20 min. The VOC, JSC, and FF have similar change regularity with that of the PCE. At an annealing time of 15 min, the CMZTSSe film had the best crystal quality, RS was at minimum, and RSh was at maximum. The CMZTSSe device achieved a maximum PCE of 4.27%, VOC was 382 mV, JSC was 26.35 mA/cm 2, and FF was 42.34%.