Light-triggered interfacial charge transfer and enhanced photodetection in CdSe/ZnS quantum dots/MoS<sub>2</sub> mixed-dimensional phototransistors

Abstract

Mix-dimensional van der Waals heterostructures (vdWHs) have inspired worldwide interests and efforts in the field of advanced electronics and optoelectronics. The fundamental understanding of interfacial charge transfer is of vital importance for guiding the design of functional optoelectronic applications. In this work, type-II 0D-2D CdSe/ZnS quantum dots/MoS₂ vdWHs are designed to study the light-triggered interfacial charge behaviors and enhanced optoelectronic performances. From spectral measurements in both steady and transient states, the phenomena of suppressed photoluminescence (PL) emissions, shifted Raman signals and changed PL lifetimes provide strong evidences of efficient charge transfer at the 0D-2D interface. A series of spectral evolutions of heterostructures with various QDs overlapping concentrations at different laser powers are analyzed in details, which clarifies the dynamic competition between exciton and trion during an efficient doping of 3.9×10¹³ cm⁻². The enhanced photoresponses (1.57×10⁴ A·W^-1) and detectivities (2.86×10¹¹ Jones) in 0D/2D phototransistors further demonstrate that the light-induced charge transfer is still a feasible way to optimize the performance of optoelectronic devices. These results are expected to inspire the basic understanding of interfacial physics at 0D/2D interfaces, and shed the light on promoting the development of mixed-dimensional optoelectronic devices in the near future.