C₃N₂H₅ Superalkali‐Enhanced Halide Perovskites for High‐Efficiency Photovoltaic Applications

The inherent instability of lead halide perovskites significantly limits their commercial applications, which has spurred extensive research into developing new halide perovskites. Herein, to identify novel halide perovskites suitable as light absorption materials, 24 promising candidates were systematically screened from a pool of over 1700 cations by applying constraints such as a vertical electron affinity of less than 3.89 eV and a tolerance factor ranging from 0.80 to 1.00. First‐principles simulations demonstrate that the C 3 N 2 H 5 + cation exhibits superior stability compared to alternative cations, enabling successful incorporation into three‐dimensional halide perovskites. The cubic (C 3 N 2 H 5 ) 1−x (NH 4 ) x MI 3 (M = Sn, Pb) perovskites display excellent dynamic stability, a direct bandgap of 1.19–1.43 eV, s‐p and p–p transitions, carrier effective masses ≤0.36 m e , exciton binding energies ≤68.77 meV, and a remarkable power conversion efficiency of 33.04−33.72%. Furthermore, their Landau levels were evaluated under varying applied magnetic fields, demonstrating their potential for advanced optoelectronic applications. These findings suggest that (C 3 N 2 H 5 ) 1‐x (NH 4 ) x MI 3 superalkali perovskites are highly promising candidates for use as photovoltaic materials.