Manipulating the Intrinsic Defect of MnS by Surface Sulfidation for Inverted Sb₂(S,Se)₃ Planar-Heterojunction Solar Cells

For the emerging Sb-2(S,Se)(3) solar cells, most high-efficiency devices employ a standard structure based on the heterojunction of weak n-type Sb-2(S,Se)(3) and heavily n-doped cadmium sulfide (CdS), and the sunlight is incident from the n-type CdS side in either superstrate or substrate structure. The weak carrier extraction ability of the n-n heterojunction as well as the parasitic absorption and toxicity from CdS further limit the efficiency improvement and practical applications. Herein, for the first time, a strategy of treating manganese sulfide (MnS) with thioacetamide to enhance its p-type conductivity is demonstrated, and a solar cell with inverted structure is constructed by forming a heterojunction with n-type Sb-2(S,Se)(3). This inverted structure well overcomes the light absorption loss and toxicity elements in the standard structure. This post-treatment effectively passivates the sulfur vacancy defects of MnS and in turn enables greater band bending in the heterojunctions for suppressed nonradiative recombination. Ultimately, the hole extraction ability of MnS shows essential improvement and enables a power conversion efficiency of 5.22% for the inverted Sb-2(S,Se)(3) solar cell. This study provides a proof-of-concept device structure for the preparation of high-efficiency Sb-2(S,Se)(3) solar cells and offers new perspectives to achieve effective intrinsic doping of metal chalcogenides.