$\beta \text{−}{\text{TeO}}_2$ has emerged as a promising wide-band-gap semiconductor for next-generation optoelectronic devices, owing to its exceptionally high hole mobility and excellent nonlinear optical properties. However, while static characteristics are well-studied, the ultrafast dynamics of photogenerated carriers—critical for device efficiency—remain poorly understood. Here, we employ ab initio nonadiabatic molecular dynamics within a surface-hopping framework to investigate the relaxation processes of electrons and holes in $\beta \text{−}{\text{TeO}}_2$. Our simulations reveal a significant asymmetry: Hole relaxation occurs on a subpicosecond timescale (0.199 ps), an order of magnitude faster than electron relaxation (2.76 ps). This imbalance, which can limit the performance of light-emitting devices, is traced to fundamental differences in relaxation pathways. Electrons near the conduction band edge encounter sparse intermediate states, leading to weak nonadiabatic coupling and a phonon bottleneck, whereas holes benefit from dense valence-band states coupled to high-frequency phonons, facilitating rapid transitions. Furthermore, cooling to 100 K suppresses carrier dynamics due to reduced phonon excitation yet preserves the asymmetry. Our work uncovers the microscopic origins of carrier relaxation asymmetry in $\beta \text{−}{\text{TeO}}_2$ and provides a predictive framework for optimizing optoelectronic functionality through external stimuli such as temperature and pressure.

Close

PrevNext

View figure in article

• Carrier dynamics
• Phonons
• Ultrafast phenomena
• Ab initio molecular dynamics
• First-principles calculations