Fast-Response Micro-Phototransistor Based on MoS2/Organic Molecule Heterojunction

Abstract

Over the past years, molybdenum disulfide (MoS2) has been the most extensively studied two-dimensional (2D) semiconductormaterial. With unique electrical and optical properties, 2DMoS2 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 MoS2. Here, we demonstrate a fast photoresponse in multilayer (ML) MoS2 by addressing a heterojunction interface with vanadylphthalocyanine (VOPc) molecules. The MoS2/VOPc van der Waals interaction that has been established encourages the PPC effect in MoS2 by rapidly segregating photo-generated holes, which move away from the traps of MoS2 toward the VOPc molecules. The MoS2/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 MoS2-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.

Tuning the Interfacial Electronic Structure of MoS2 by Adsorption of Cobalt Phthalocyanine Derivatives

“…By constructing such weakly interacting TMDC/TPc heterostructures, the photoresponsivity and response time in phototransistors were improved compared to the pure TMDC components. − Furthermore, TPcs could be used for defect engineering and the resulting enhancement of photoluminescence quantum yields. − In this work, we seek to modify the type and concentration of charge carriers in n-type MoS 2 by the adsorption of cobalt phthalocyanine (CoPc) and its perfluorinated derivative (CoPcF 16 ). While the interface between TMDCs and other TPcs has been explored previously, the detailed electronic structure in interfaces between cobalt phthalocyanine derivatives and MoS 2 has not been studied so far .…”

Investigations of MoS2-Based Self-Powered M–S–M Photodetectors with Low Defect Density and Fast Response and Low-Temperature Characteristics

“…Due to the requirement of more complex layered structures and high cost, there has been a few researches in recent years to explore developments in the field of photodetectors based on phototransistor structures (the mainstream structure of a photodetector is the PN or PIN structure). 16 It should be noted that with a gate, the gate oxide can be classified as a phototransistor. Because at thermal equilibrium, the Fermi levels of the two different materials should be equal and the vacuum level must also be continuous, the junction of the metal−semiconductor forms a Schottky barrier with a rectifying effect.…”

“…Due to the requirement of more complex layered structures and high cost, there has been a few researches in recent years to explore developments in the field of photodetectors based on phototransistor structures (the mainstream structure of a photodetector is the PN or PIN structure) . It should be noted that with a gate, the gate oxide can be classified as a phototransistor.…”

Ultrafast Formation of Charge Transfer Trions at Molecular-Doped 2D MoS2 Interfaces

“…One economical and efficient approach is to create heterojunctions, including TMD-TMD [10][11][12] and molecule-TMD heterojunctions. [10][11][12][13][14] For example, it was recently shown that many-body control of electron localization in moiré heterostructures can greatly improve catalytical performance 15 . Similarly, doping monolayer TMD with molecules could control interfacial band alignment and its chemical and electrostatic environments 16 .…”