Hot carrier dynamics in MoS2/WS2 heterostructure

Abstract

TMDs based heterostructure have drawn much attention for its potential application in photoelectric devices benefiting from the rapid and effective carrier separation and ultra-long interlayer exciton lifetime. Recent studies on carrier dynamics of TMDs based heterostructures are mainly focused on the transfer process of photo-generated carriers across the interface and lifetime of interlayer exciton but little attention is paid on the dynamics of hot carriers. Here, the carrier dynamics of hot carriers in MoS2/WS2 heterostructure is investigated by transient absorption spectra. Rapid separation of electron and hole is observed. More importantly, hot carriers of C exciton, which contribute to the absorption of most of the visible light, could compensate for the carrier loss in the band edge exciton energy band through the intervalley transfer process. This re-injection process of hot carriers of C exciton could compensate for carrier depletion in photoelectric devices, thus may greatly improve the light utilization in optoelectronic devices.