Pseudo-halogen regulation technology for air preparation of high-efficiency inverted broadband gap inorganic perovskite photovoltaic devices

Trans-structured inorganic perovskite solar cells with a band gap of 1.75-1.80 eV are considered as one of the candidates for the top sub-cells of all-perovskite tandem devices. However, there are few reports on the related lamination. The fundamental reason is that the power conversion efficiency (PCE) is difficult to continue to improve due to the dense non-radiative recombination centers in the bulk and surface of the film. In view of this bottleneck, cadmium acetate (Cd (CH₃COO)₂) containing pseudohalogen CH₃COO⁻ was directly added to the precursor solution, and the coordination between CH3COO- and lead ions was used to finely regulate the nucleation and crystal growth of perovskite. Compared with conventional organic additives, the proportion of the organic part of Cd (CH₃COO)₂ is extremely low, which can also significantly passivate defects and inhibit non-radiative recombination while maintaining photothermal stability. Finally, the inverted wide band gap (1.75 eV) inorganic perovskite solar cell prepared in the air environment obtained 19.06 % PCE and compared with the device without Cd (CH₃COO)₂ treatment, the device showed better wet, heat and light multiple stability.