A promising photovoltaic material Cu2MnSn(S,Se)4: Film growth and its application in solar cell

Chalcogenides, such as CdTe, Cu(In,Ga)(S,Se)(2) and Cu2ZnSn(S,Se)(4), have made significant progress in their thin-film photovoltaic performance, but the toxicity (CdTe) and scarcity (Cu(In,Ga)(S,Se)(2)) of the constituent elements, as well as the inevitable anti-site disorder (Cu2ZnSn(S,Se)(4)), limit the further improvement of efficiency. In this work, a new thin-film absorber, Cu2MnSn(S,Se)(4), is studied in terms of both film growth and characterization. We prepare the precursor film by the sol-gel method followed by selenization at high temperature. The absorbance of the precursor film is higher than 98% at wavelengths of 200-1300 nm. The crystallinity and the phase transformation of the prepared film can be tailored greatly by modifying the selenization process. When the selenization temperature is 570 degrees C and the selenization time is 30 min, a highly-crystalline, stannite-structured Cu2MnSn(S,Se)(4) film is obtained. A solar cell fabricated with such Cu2MnSn(S,Se)(4) film as the absorber layer achieves efficiency of 1.79%, which is the highest efficiency reported to date for this material. This study demonstrates that Cu2MnSn(S,Se)(4) is a promising photovoltaic material and has huge potential for the fabrication of low-cost solar cell.