Nuclear Quantum Effects Enhance Structural Stability but Accelerate Charge Carrier Recombination in MHyPbBr Perovskite.

Hybrid organic-inorganic perovskites exhibit significant nuclear quantum effects (NQEs) due to their light hydrogen atoms. By performing ring polymer molecular dynamics, ab initio molecular dynamics, and nonadiabatic molecular dynamics simulations on the MHyPbBr (MHy = CHNHNH) perovskites, we demonstrate that NQEs stabilize the lattice by suppressing atomic motions and accelerate nonradiative charge recombination. This stabilization arises from the synergistic effects of the Pb-N coordination bonds and N-H···Br hydrogen bonds, which enhance organic-inorganic interactions. As a result, Pb-Br octahedra, particularly [Pb(1)Br] octahedra supporting electron and hole, are well-preserved, promoting electronic wavefunction delocalization and increasing electron-hole overlap. These effects enhance nonadiabatic coupling by overcoming the reduced atomic motions. Overall, this and the prolonged decoherence time accelerate the nonradiative electron-hole recombination due to NQEs. Our study highlights the unique influence of NQEs on the geometrical stability and charge carrier dynamics in MHyPbBr, offering fundamental insights for future material design.