Cu2ZnSnSe4 device obtained by formate chemistry for metallic precursor layer fabrication

Cu2ZnSnSe4 films were prepared by selenization of metallic precursors obtained by a new wet process involving metal formates. Cu(HCOO)2 and Zn(HCOO)2 were used as copper and zinc sources respectively, while tin was introduced as a methoxide.The elemental analysis of the resulting absorber layers revealed a very low carbon content (less than 0.2wt%), which is believed to be a feature that chemical methods need to have in order to stand out as valuable alternatives to high-vacuum processes in this field. Solar cells with efficiencies of up to 2.39% with Voc of 207mV, a Jsc of 31.2mA/cm2 and a fill factor of 37.1% were achieved for these copper-poor CZTSe absorbers.