Effects of Indium Incorporation on Structural and Photovoltaic Properties of Cu2ZnSnS4 Thin Films

Indium-incorporated Cu2(Zn,Sn)S4 (In-CZTS) films were fabricated by using a spray pyrolysis technique. The structural analysis showed successful formation of In-CZTS films without any impurity components when the In/(Zn +Sn) ratio was lower than 0.2. From the morphology, we found that the In incorporation into the CZTS laticce suppressed the grain growth, leading to poor quality especially for the film with high indium contents. However, for the sample at low indium ratio (In/(Zn+Sn) = 0.01), the conversion efficiency was improved: the maximum conversion efficiency of 6.0% was achieved.