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

Abstract

Antimony Selenide (Sb2Se3) thin-film solar cell configurations with alternative buffer layers are proposed to improve the efficiency by minimizing open‐circuit voltage offset (Voc,offset). The conduction band offsets have been optimized not only at absorber/buffer (ΔEC‐BA) but also at buffer/transparent conductive oxide (ΔEC-TB). Voltage‐independent recombination rates in the quasi‐neutral region (Rb0), the space‐charge region (Rd0), and at the absorber/buffer interface (Ri0) of the Sb2Se3 solar cells with various configurations are individually modelled. The development of cell configurations causes to decrease the Ri0, Rd0, and Rb0, 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 ΔEC‐BA of 0.29 eV and ΔEC‐TB of −0.2 eV, therefore considerably reducing Voc,offset to approximately 0.52 V, and improving the efficiency to 15.46%.