PbSe‐Induced Sb 2 S 3 Crystallization and Interface Band Optimization for High‐Efficiency Bulk Heterojunction Sb 2 S 3 Solar Cells

Abstract Sb 2 S 3 solar cells have significant advantages in non‐toxicity and stability compared to perovskite solar cells. However, their power conversion efficiency still needs to be improved urgently. One of the main reasons is that the crystal orientation of 2D Sb 2 S 3 is difficult to control, and there are a large number of dangling bonds at the crystal surface, which make it difficult for photogenerated charges to efficiently conduct in the desired direction and causes serious charge recombination. In order to overcome various challenges, including the core difficulties mentioned above, herein, ultra‐thin PbSe is deposited on TiO 2 /CdS nanorods to induce preferential crystallization of Sb 2 S 3 films in the [ hk 1] direction that is more conducive to charge transport, bidirectionally passivate defects at the CdS/Sb 2 S 3 heterojunction interface. At the same time, the crystallization in the [ hk 0] direction, which is not conducive to charge transport, is suppressed in the Sb 2 S 3 thin film, and the interfacial band structure is optimized. Ultimately, the efficiency of target Sb 2 S 3 solar cell is improved to 8.06%, which is the highest efficiency of bulk heterojunction Sb 2 S 3 solar cells. This study provides new ideas for efficient Sb 2 S 3 solar cells in novel device design, Sb 2 S 3 crystallization optimization, and interface engineering.