Fast-Response Micro-Phototransistor Based on MoS 2 /Organic Molecule Heterojunction.

Over the past years, molybdenum disulfide (MoS ₂ ) has been the most extensively studied two-dimensional (2D) semiconductormaterial. With unique electrical and optical properties, 2DMoS ₂ is considered to be a promising candidate for future nanoscale electronic and optoelectronic devices. However, charge trapping leads to a persistent photoconductance (PPC), hindering its use for optoelectronic applications. To overcome these drawbacks and improve the optoelectronic performance, organic semiconductors (OSCs) are selected to passivate surface defects, tune the optical characteristics, and modify the doping polarity of 2D MoS ₂ . Here, we demonstrate a fast photoresponse in multilayer (ML) MoS ₂ by addressing a heterojunction interface with vanadylphthalocyanine (VOPc) molecules. The MoS ₂ /VOPc van der Waals interaction that has been established encourages the PPC effect in MoS ₂ by rapidly segregating photo-generated holes, which move away from the traps of MoS ₂ toward the VOPc molecules. The MoS ₂ /VOPc phototransistor exhibits a fast photo response of less than 15 ms for decay and rise, which is enhanced by 3ordersof magnitude in comparison to that of a pristine MoS ₂ -based phototransistor (seconds to tens of seconds). This work offers a means to realize high-performance transition metal dichalcogenide (TMD)-based photodetection with a fast response speed.