Conduction Band Energy‐Level Engineering for Improving Open‐Circuit Voltage in Antimony Selenide Nanorod Array Solar Cells

Antimony selenide (Sb(2)Se(3)) nanorod arrays along the [001] orientation are known to transfer photogenerated carriers rapidly due to the strongly anisotropic one‐dimensional crystal structure. With advanced light‐trapping structures, the Sb(2)Se(3) nanorod array‐based solar cells have excellent broad spectral response properties, and higher short‐circuit current density than the conventional planar structured thin film solar cells. However, the interface engineering for the Sb(2)Se(3) nanorod array‐based solar cell is more crucial to increase the performance, because it is challenging to coat a compact buffer layer with perfect coverage to form a uniform heterojunction interface due to its large surface area and length–diameter ratio. In this work, an intermeshing In(2)S(3) nanosheet‐CdS composite as the buffer layer, compactly coating on the Sb(2)Se(3) nanorod surface is constructed. The application of In(2)S(3)‐CdS composite buffers build a gradient conduction band energy configuration in the Sb(2)Se(3)/buffer heterojunction interface, which reduces the interface recombination and enhances the transfer and collection of photogenerated electrons. The energy‐level regulation minimizes the open‐circuit voltage deficit at the interfaces of buffer/Sb(2)Se(3) and buffer/ZnO layers in the Sb(2)Se(3) solar cells. Consequently, the Sb(2)Se(3) nanorod array solar cell based on In(2)S(3)‐CdS composite buffers achieves an efficiency of as high as 9.19% with a V (OC) of 461 mV.