Spatially Confined Liquid-Precursor CVD Enables Direct Growth of WS2/MoS2 Twisted Heterostructures

Abstract

The performance of two-dimensional transition metal dichalcogenide (TMD) heterostructures is profoundly influenced by their interlayer coupling with modulating twist angles. However, it is still a great challenge to achieve thermodynamically unfavorable twisted TMD heterostructures. Herein, WS2/MoS2 heterostructures with unfavorable twist angles from 0° to 100° were directly synthesized by a spatially confined liquid-precursor-assisted CVD growth. Spectroscopic analyses reveal that non-0° twisted heterostructures exhibit weakened interlayer coupling with the redshift of the Raman A1g mode. Low-temperature photoluminescence indicates the resonance energy transfer from the MoS2 B exciton to the WS2 A exciton, enhancing WS2 emission. The thermodynamically unfavorable (20°, 30°, and 90°) twisted heterostructures are found to possess much larger interfacial work function difference and longer exciton lifetimes, indicating more efficient interfacial charge transfer. This work clarifies the fundamental role of twist angle in modulating the built-in electric field and exciton dynamics of WS2/MoS2 heterostructures and underscores their great potential for practical optoelectronic applications.