Bandgap-Tunable Organic–Inorganic Halide Perovskite Family ABI ₃ (A = MA, FA, NH ₄ ; B = Pb, Sn, Ge) under Hydrostatic Pressure

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Chinese explanation / 中文解读

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Original abstract

In recent years, organic–inorganic halide perovskite solar cells have attracted widespread attention due to their tunable band gap, high optical absorption coefficient, and favorable structural stability. In this study, we employed first-principles calculations and density functional theory to investigate the electronic structure, mechanical properties, optical characteristics, and stability of ABI3 (A = MA, FA, NH4; B = Pb, Sn, Ge). We substituted Pb with its group counterparts Sn and Ge while retaining Pb at the B-site for comparative analysis. Through calculations of perovskite stability factors, precursor reaction energies, and ab initio molecular dynamics, we confirmed that lead-free perovskites exhibit favorable thermodynamic and structural stability under inert conditions, making them viable replacements for Pb. Our findings indicate that modifying the B-site element enables bandgap tuning, allowing for light absorption across different spectral ranges. Our theoretical research indicates that under hydrostatic pressure, the bandgap can be further modulated. NH4GeI3 demonstrates heightened sensitivity in both lattice parameters and bandgap values, exhibiting a bandgap reduction of 0.74 eV at 1.1 GPa. Its substantial pressure-bandgap response (S = 0.67 eV/GPa) suggests potential as a pressure-sensitive photodetector material. This study elucidates the property variations in Sn- and Ge-substituted perovskites, providing interesting insights for the further development and application of environmentally friendly lead-free organic–inorganic halide perovskites.

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