A DMSO/MOE mixed solvent system for improving the morphology and efficiency of kesterite solar cell

A mixed dimethyl sulfoxide (DMSO) and 2-methoxy ethanol (MOE) solvent system was developed to prepare high-quality kesterite Cu2ZnSn(S, Se)4 (CZTSSe) film. The precursor films made pure DMSO system show a tube-like microstructure morphology, which can be changed by adding MOE to the solution. The increase of MOE in the precursor solution is a key in the crystalline characteristic of the absorber and connecting performance with thin film solar cells. As VMOE = VDMSO, the CZTSSe layer can achieve good contact with the back electrode and obtain large grains across layers. The addition of MOE solvent effectively improves the fill factor (FF). Specifically, both the fill factor and efficiency are increased from 49.67% and 6.43% to 64.83% and 10.99%, respectively, with the addition of 2 mL of MOE into precursor solution prepared by DMSO.