Dark-current reduction accompanied photocurrent enhancement in p-type MnO quantum-dot decorated n-type 2D-MoS2-based photodetector.

A highly crystalline single- or few-layered 2D-MoS₂ induces a high dark current, due to which an extremely small photocurrent generated by a few photons can be veiled or distorted. In this report, we show that suppression in the dark current with the enhancement in the photocurrent of a 2D-based photodetector, which is a prerequisite for photoresponse enhancement, can be achieved by constructing an ideal p‐n junction based on functionalizing n-type 2D-MoS₂ with p-type quantum dots (QDs). Highly crystalline solution-processed manganese oxide QDs (MnO QDs) are synthesized via the pulsed femtosecond laser ablation technique in ethanol. The ablated MnO QDs are spray-coated on an exfoliated 2D-MoS₂ substrate with interdigitated Au electrodes through N₂-assisted spraying. In the resulting MnO QD-decorated 2D-MoS₂ photodetector with a heterojunction, dark current is reduced and is accompanied by photocurrent enhancement, thereby markedly improving the photoresponsivity and detectivity of MoS₂-based devices. To elucidate the underlying mechanisms contributing to this enhancement, power- and wavelength-dependent photoresponses, along with material characterizations based on spectroscopic, chemical, morphological measurements, and analyses, are discussed. [ABSTRACT FROM AUTHOR]