Synergizing between interband and intraband defect states in prolonging the charge carrier lifetime of InSe/SiH heterojunctions

Abstract

Experiments have demonstrated that defect states can regulate the charge carrier dynamics in heterojunctions. However, the underlying mechanism still remains under debate. Using nonadiabatic molecular dynamics, we have investigated the influence of inter and intraband defect states on charge relaxation in InSe/SiH heterojunctions. The simulations revealed that inter and intraband defect states have a weak effect on electron transfer, whereas they exert a strong influence on hole transfer and electron–hole recombination. Compared to the pristine system, the selenium vacancy creates two interband shallow electron trapping states and one intraband hole trapping state. The interband electron trapping states can capture photo-generated electrons, while the intraband hole trapping state accelerates hole transfer. The synergy between inter and intraband defect states suppresses the charge recombination by a factor of 8.3. This simulation rationalizes the influence mechanism of inter and intraband defect states on charge carrier dynamics, suggesting a valuable principle for enhancing the performance of heterojunction photocatalysts.