Thickness-dependent carriers transport in Sb₂Se₃ thin film solar cells

The structural design of n-i-p in antimony selenide (Sb₂Se₃) thin film solar cells can effectively improve the low carrier collection efficiency caused by the lower doping concentration of Sb₂Se₃. However, the unideal carrier transport ability of the intrinsic light-absorbing layer remains a major limitation for its power conversion efficiency improvement. Herein, it is discovered that the carrier transport in Sb₂Se₃ thin films strongly depends on the film thickness of the absorber layer in n-i-p structure. By exploring the carrier transport mechanism under different thicknesses of light-absorbing layers, a suitable absorber layer with thickness of 550 nm is demonstrated can effectively separate, transport, and extract photogenerated carriers in Sb₂Se₃ solar cells. Finally, the vapor transport deposition processed Sb₂Se₃ solar cells achieve the highest PCE of 7.62% with a short-circuit current density of 30.71 mA·cm⁻². This finding provides a constructive guidance for the future researches on Sb₂Se₃ thin film solar cells with n-i-p structure.