Nonadiabatic Dynamics of Ultrafast Interlayer Charge Transfer and Extended Photocarrier Lifetimes in GaSe/InTe Heterostructures

Designing high-performance two-dimensional (2D) heterostructures and revealing the microscopic mechanisms governing photocarrier dynamics are essential for advancing optoelectronic and photovoltaic technologies. Here, we perform compelling ab initio time-dependent nonadiabatic molecular dynamics to explore the photoexcited carrier dynamics in GaSe/InTe, as a prototype for group-III monochalcogenide heterostructures. The GaSe/InTe heterostructure exhibits strong light-harvesting capability across the ultraviolet and visible spectral regions and features type-II band alignments that promote efficient charge separation. In the A′A-stacked configuration, photoexcitation induces ultrafast interlayer electron transfer from InTe to GaSe within 119 fs, while hole transfer in the reverse direction completes within 314 fs. Notably, electron–hole recombination occurs on the extended nanosecond time scale, approximately 4 orders of magnitude slower than charge separation, ensuring highly efficient spatial separation of photogenerated carriers. The extended lifetimes originate from the localized interfacial electronic states and the markedly reduced nonadiabatic coupling that suppresses the recombination pathways. Moreover, this desirable behavior, characterized by ultrafast charge separation and extended carrier lifetimes, persists across all high-symmetry stacking configurations. These findings establish a fundamental understanding of photocarrier behavior in group-III monochalcogenide heterostructures, providing valuable guidance for the rational design of next-generation 2D photovoltaic and optoelectronic materials.