Weak Anharmonicity Rationalizes the Temperature-Driven Acceleration of Nonradiative Dynamics in Cu2ZnSnS4Photoabsorbers

We report a time-domain ab initio investigation of the nonradiative electron–hole recombination in quaternary Cu2ZnSnS4 (CZTS) at different temperatures using a combination of time-dependent density functional theory and nonadiabatic molecular dynamics. Our results demonstrate that higher temperatures increase both inelastic and elastic electron–phonon interactions. Elevated temperatures moderately increase the lattice anharmonicity and cause stronger fluctuations of electronic energy levels, enhancing the electron–phonon coupling. The overall nuclear anharmonic effect is weak in CZTS, which can be ascribed to their stable bonding environment. Phonon-induced loss of electronic coherence accelerates with temperature, due to stronger elastic electron–phonon scattering. The enhanced inelastic electron–phonon scattering decreases charge carrier lifetimes at higher temperatures, deteriorating material performance in optoelectronic devices. The detailed atomistic investigation of the temperature-dependent charge carrier dynamics, with particular focus on anharmonic effects, guides the development of more efficient solar cells based on CZTS and related semiconductor photoabsorbers.