Atomically thin two-dimensional (2D) semiconductors boast numerous intriguing enhanced material properties for various potential electronic device applications. For optoelectronic devices, such as photodetectors and photovoltaics, an efficient light harvesting is highly demanded, and the relatively low absolute optical absorption of 2D semiconductors can, therefore, limit associated device performances, including photodetector responsivity and solar cell power conversion efficiency. Recently, the sensitization by quantum dots (QDs) has shown promises for improving the optical absorption in 2D semiconductors. In this talk, I will highlight our recent efforts towards utilizing QD sensitization for improving the photo-response of 2D semiconductor field-effect transistor (FET) photodetectors. The first example demonstrates a 500% enhancement in photocurrent response by the application of energy transfer from CdSe/ZnS core/shell QDs in 2D SnS2, a model 2D system with indirect band gap nature. Also detailed is the case of 2D MoS2, where we show that the light-intensity-dependent photo-response characterized by scanning photocurrent microscopy (SPCM) can distinguish two fundamental modes of interfacial interaction between QDs and 2D materials, namely energy and charge transfers, which are extremely difficult to distinguish under typically optical interrogation methods. I will try to discuss the potential implication of these two modes towards the optoelectronic application of QD-2D hybrid materials.
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