A fast 2D MoS photodetector with ultralow contact resistance.

Two-dimensional (2D) transition metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS), hold great promise for next-generation nanoelectronic and nanophotonic devices. While high photoresponsivity and broad spectral coverage (UV-IR) have been reported, the slow response time of MoS photodetectors caused by their unfavorable RC characteristics is still a major limit in current devices. Once the RC limit issue is resolved, the intrinsic saturation drift velocity of electrons in TMDs (∼10 cm s) may enable GHz opto-electronic operations.

Organic-Inorganic Rubrene/WS Heterostructure for Broadband Detection and Polarization Imaging.

Organic single crystals exhibit improved carrier mobility, longer exciton diffusion length, anisotropic charge transport, and unique linear dichroism, while its high exciton binding energy seriously limits the free-carrier generation and photoelectric conversion efficiency. Layered van der Waals heterostructures, which integrate organic crystals with high mobility two-dimensional (2D) inorganic semiconductors, are promising for promoting exciton dissociation and boosting sensitivity by utilizing the interfacial potential and photogating effect. In this work, organic single-crystal rubrene is integrated with a few-layer WS to design the high-performance photodetector.

Sensitive organic/inorganic polarized photodetectors enhanced by charge transfer with image sensing capacity.

Organic photodetectors (OPDs) have attracted increasing attention in the future wearable sensing and real-time health monitoring, due to their intrinsic features including the mechanical flexibility, low-cost processing and cooling-free operations; while their performances are lagging as the results of inferior carrier mobility and small exciton diffusion coefficient of organic molecules. Graphene exhibits the great photoresponse with wide spectral bandwidth and high response speed. However, weak light absorption and the absence of a gain mechanism have limited its photoresponsivity.

Asymmetric Schottky Barrier in Rubrene Transistor via Monolayer Graphene Insertion toward Self-Powered Imaging.

Organic semiconductor materials featuring lightweight, and flexibility may play a significant role in various future applications, such as foldable displays, wearable devices, and artificial skin. For developing high-performance organic devices, organic crystals are highly desired, while a remaining fundamental issue is their contact problem. Here, we have grown a high-quality rubrene single crystal by utilizing a simple in-air sublimation technique.

Gate Controlled Photocurrent Generation Mechanism in Air-Grown Organic Single Crystals for High-Speed Multiband Imaging.

Organic semiconductors herald new opportunities for fabricating high-performance flexible and wearable optoelectronic devices owing to their intrinsic mechanical flexibility, excellent optical absorption, and cool-free operation. The photocurrent generation mechanisms are of multiple physical origins, including photoconductive, photovoltaic, and photogating effects, and the influence of individual effects on the device figures-of-merit is still not well understood. Here we fabricated a high-performance pentacene single-crystal transistor employing graphene electrodes and demonstrated the modulation from the photogating mechanism to the photoconduction effect by controlling gate bias.