Transient Reflection Spectroscopy on Ultrafast Interlayer Charge Transfer Processes in a MoS2/WSe2 Van der Waals Heterojunction

Release time:2021-11-12

Impact Factor:4.189

Journal:The Journal of Physical Chemistry C

Abstract:Understanding the dynamical process of charge transfer (CT) across the Van der Waals heterostructure (VdWHs) is vitally important for improving photovoltaic conversion efficiency at the atomically thin interfaces. Here ultrafast dynamics of VdWHs constructed by vertically stacking monolayer molybdenum disulfide (MoS2) onto tungsten diselenide (WSe2) with a multilayer hexagonal boron nitride (hBN) substrate was investigated by transient reflection measurements. MoS2 and WSe2 were selectively excited to obtain direct evidence of the CT processes. It is interesting to note that the bleaching band of MoS2/WSe2 is composed of two different contributions with different dynamics under excitation at 650 nm: direct excitation induced bleaching of WSe2 (with decay time constant of ~ 63 ps) and bleaching signals arising from photo-induced hole transfer (with decay time constant of ~303 ps). The interlayer charge transfer process was found to occur on the sub-picosecond time scale, resulting in long-lived interlayer spatially separated charge carriers (~hundreds of picoseconds). These results imply potentially high photovoltaic conversion efficiency of these heterostructures.

Co-author:Menglong Zhu, Tianhua Ren, Jun He, Kian Ping Loh

First Author:Zhihui Chen

Indexed by:Journal paper

Correspondence Author:Qing-Hua Xu

Translation or Not:no

Date of Publication:2021-11-12

Included Journals:SCI