Bulk Heterojunction Antimony Selenosulfide Thin‐Film Solar Cells with Efficient Charge Extraction and Suppressed Recombination

Abstract As an emerging earth‐abundant light harvesting material, antimony selenosulfide (Sb₂(S,Se)₃) has received tremendous attention for photovoltaics. Manipulating the carrier separation and recombination processes is critical to achieve high device efficiency. Compared to the conventional planar heterojunction (PHJ), the bulk heterojunction (BHJ) configuration affords great potential to enable efficient charge extraction. In this work, BHJ Sb₂(S,Se)₃ solar cells are constructed based on CdS nanorod arrays (NRAs). Highly ordered CdS NRAs with appropriate nanorod lengths and diameters are obtained by regulating the growth environment and screening different substrates for CdS deposition. A low‐temperature oxygen doping strategy implemented on CdS NRAs is further developed to improve the optoelectronic and defect properties as well as form a favorable cascade band structure for CdS NRAs, so as to realize more efficient charge extraction and suppressed recombination at the heterointerface. As a result, the CdS NRAs‐based superstrated BHJ Sb₂(S,Se)₃ solar cell yields a considerable power conversion efficiency of 8.04%, outperforming that of the PHJ device. A careful comparative study of PHJ and BHJ based on electrostatic field simulations indicates that the BHJ allows more efficient charge extraction and transport. This work highlights the great potential of BHJ configuration for constructing high‐performance antimony chalcogenide solar cells.