Surface engineered wide-bandgap all-inorganic perovskite solar cells achieve a fill factor exceeding 82%

Cesium lead iodide bromide (CsPbIBr 2 ) perovskite solar cells (PSCs) exhibit enhanced stability compared to other inorganic perovskite compositions. However, their photovoltaic performance remains a major challenge, limiting their power conversion efficiencies (PCEs). This study introduces an innovative device design aimed at improving the surface potential of CsPbIBr 2 PSCs by enhancing their optoelectronic properties. The method of deploying a thin layer of tetraphenyl-porphine zinc (TPP-Zn) over perovskite active layer not only suppressed surface residues and defects but also facilitated smoother charge carrier dynamics within the photovoltaic device. Interaction between TPP-Zn and the uncoordinated metal cations of CsPbIBr 2 perovskite effectively passivates the surface trap states of the film, resulting in enhanced charge transport and suppression of charge recombination. We further devised a solar cell model using SCAPS-1D to analyze the photoelectric characteristics of the proposed wide bandgap CsPbIBr 2 PSCs and found that the numerical results obtained are well in line with experimental data. The optimized CsPbIBr 2 PSC achieves a remarkable PCE exceeding 13.47%, with an open-circuit voltage ( V OC ) of 1.29 V, a fill factor (FF) of 82.3%, and a short-circuit current density ( J SC ) of 12.69 mA cm -2 for a device area of 0.16 cm 2 and achieves a PCE of 11.29% for a device area of 1.02 cm 2 . This straightforward and effective method offers a viable path toward the fabrication of stable and highly efficient inorganic perovskite devices.