Surface Crystallization Enhancement and Defect Passivation for Efficiency and Stability Enhancement of Inverted Wide-Bandgap Perovskite Solar Cells

Wide-bandgap (WBG) inverted perovskite solar cells (PSCs) are used as the top cell for tandem solar cells, which is an effective way to outperform the Shockley–Queisser limit. However, the low efficiency and poor phase stability still seriously restrict the application of WBG inverted PSCs. Here, the surface of the WBG perovskite film was passivated by the synthesized 1,2,4-tris(3-thienyl)benzene (THB). The THB size well matches with the halogen ion vacancy on the perovskite surface, and the S atom in THB can strongly interact with Pb2+ on the surface of the WBG perovskite film to the greatest extent, which effectively passivates surface defects and suppresses the recombination of carriers caused by these defects. At the same time, the S atom in THB occupied the migration site of the halogen ions, which inhibits the migration of halogen ions. Due to the strong conjugation effect and stability of THB, it can be locked on the surface of perovskite to increase the lattice strength and inhibit the segregation of photoinduced halide, thus improving the performance and operational stability of PSCs. The THB-modified WBG (Eg = 1.71 eV) PSC achieves a maximum power conversion efficiency of 20.75%, and its 99.0% is retained after 1512 h at a relative humidity of 10–25%. Under the irradiation of 1000 lx LED light, the indoor power conversion efficiency of the THB-modified WBG PSC reaches 34.15%.