Reducing Nonradiative Recombination in Halide Perovskites through Appropriate Band Gaps and Heavy Atomic Masses

Abstract

Halide perovskite optoelectronic devices achieve high energy conversion efficiencies. However, their efficiency decreases significantly with an increase in temperature. This decline is likely caused by changes in nonradiative recombination and electron–phonon coupling, which remain underexplored. When the perovskite lattice temperature increases, anharmonicity induces energy level fluctuation and band gap narrowing by modulating electron–phonon interactions. As lattice vibrations intensify, high-frequency phonons progressively dominate the carrier dynamic processes in halide perovskites, thereby strengthening the coupling between the electronic subsystem and high-frequency phonons. The increased overlap of electron wave functions strengthens non-adiabatic coupling, thereby accelerating the nonradiative recombination process. On the basis of these findings, we propose the introduction of appropriate band gap materials and heavy atoms at the B-site and X-site to modulate electron–phonon coupling, thereby mitigating nonradiative recombination and enhancing halide perovskite solar cell performance.