Nuclear Quantum\nEffects Enhance Structural Stability\nbut Accelerate Charge Carrier Recombination in MHyPbBr<sub>3</sub> Perovskite

Hybrid organic–inorganic perovskites\nexhibit significant\nnuclear quantum effects (NQEs) due to their light hydrogen atoms.\nBy performing ring polymer molecular dynamics, ab initio molecular\ndynamics, and nonadiabatic molecular dynamics simulations on the MHyPbBr<sub>3</sub> (MHy<sup>+</sup> = CH<sub>3</sub>NH<sub>2</sub>NH<sub>2</sub><sup>+</sup>) perovskites, we demonstrate that NQEs stabilize the\nlattice by suppressing atomic motions and accelerate nonradiative\ncharge recombination. This stabilization arises from the synergistic\neffects of the Pb–N coordination bonds and N–H···Br\nhydrogen bonds, which enhance organic–inorganic interactions.\nAs a result, Pb–Br octahedra, particularly [Pb(1)Br<sub>6</sub>]<sup>4–</sup> octahedra supporting electron and hole, are\nwell-preserved, promoting electronic wavefunction delocalization and\nincreasing electron–hole overlap. These effects enhance nonadiabatic\ncoupling by overcoming the reduced atomic motions. Overall, this and\nthe prolonged decoherence time accelerate the nonradiative electron–hole\nrecombination due to NQEs. Our study highlights the unique influence\nof NQEs on the geometrical stability and charge carrier dynamics in\nMHyPbBr<sub>3</sub>, offering fundamental insights for future material\ndesign.