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Sn-based perovskites have intrinsic defects, such as Sn vacancies, oxidised components (Sn4+), and local lattice strain in the perovskite crystalline structure. In this study, Zn metal powder (Zn0) was introduced to reduce Sn oxidation in the solution step based on the redox potential difference. Additionally, Zn2+ was introduced in the perovskite precursor, which decreased the intrinsic defects and lattice strain of the perovskite films. The diffusion length, particularly that of the hole, increased with a reduction in the lattice strain, and Zn doping led to interfacial energy-level alignment of the perovskite and hole-transporting layers. The reduced lattice strain decreased the defect density and charge carrier recombination of perovskite devices. The power conversion efficiency of the Zn-doped Sn-based perovskite solar cell was improved to 11.39% compared to the 8.56% of the reference device. [ABSTRACT FROM AUTHOR]

Phenyl-C 61 -butyric acid methyl ester (PCBM) can be used as a passivation material in perovskite solar cells (PeSCs) in order to reduce the trap site of the perovskite. Here, we show that a thick PCBM layer can form a smoother surface on the SnO 2 substrate, improving the grain size and reducing the microstrain of the perovskite. High-temperature annealing treatment of PCBM layer not only increases its solvent resistance to perovskite precursor or antisolvent, but also enhances its molecular alignment, resulting in improved conductivity as an electron transport layer. High-temperature annealed PCBM (HT-PCBM) effectively minimizes trap-assisted nonradiative recombination by reducing trap density in perovskite and improving the electrical properties at the interface between SnO 2 and perovskite layers. This HT-PCBM process significantly enhances the performance of the PeSCs, including the open-circuit voltage ( V OC ) from 0.39 to 0.77 V, fill factor from 52% to 65%, and power conversion efficiency (PCE) from 6.03% to 15.50%, representing substantial improvements compared to devices without PCBM. This PCE is the highest efficiency among conventional (n-i-p) Sn-Pb PeSCs reported to date. Moreover, passivating the trap sites of SnO 2 and separating the interface between the Sn-containing perovskite and the substrate effectively have improved the stability of the Sn-Pb perovskite in the n-i-p structure. The optimized best device with HT-PCBM has maintained an efficiency of over 90% for more than 300 h at 85 °C and 5000 h at room temperature in a glovebox atmosphere.