Alternative buffer layers in Sb2Se3 thin-film solar cells to reduce open-circuit voltage offset

Antimony Selenide (Sb2Se3) thin-film solar cell configurations with alternative buffer layers are proposed to improve the efficiency by minimizing open-circuit voltage offset (V-oc,V-offset). The conduction band offsets have been optimized not only at absorber/buffer (Delta EC-BA) but also at buffer/transparent conductive oxide (Delta EC-TB). Voltage-independent recombination rates in the quasi-neutral region (R-0(b)), the space-charge region (R-0(d)), and at the absorber/buffer interface (R-0(i)) of the Sb2Se3 solar cells with various configurations are individually modelled. The development of cell configurations causes to decrease the R-0(i), R-0(d), and R-0(b), consequently reducing the Voc,offset. It is found that the solar cell configuration of Mo/MoSe2/Sb2Se3/TiO2/ZnO0.4S0.6/Zn0.93Mg0.07O/ZnO:Al is suitable with the Delta EC-BA of 0.29 eV and Delta EC-TB of -0.2 eV, therefore considerably reducing V-oc,V- offset to approximately 0.52 V, and improving the efficiency to 15.46%.