Photodetectors capable of detecting light in a wide spectrum is central to diversified optoelectronic applications in spectroscopy, remote sensing, imaging and optical communication. [1] Two-dimensional (2D) transition metal dichalcogenides (TMDs) provide a tremendous potential for broadband optoelectronics due to their relatively high mobility, appropriate bandgaps, and flexibility. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In particular, TMD layers of different bandgaps and doping (p or n types) can be stacked together into van der 2D atomic sheets of transition metal dichalcogenides (TMDs) have a tremendous potential for next-generation optoelectronics since they can be stacked layer-by-layer to form van der Waals (vdW) heterostructures. This allows not only bypassing difficulties in heteroepitaxy of lattice-mismatched semiconductors of desired functionalities but also providing a scheme to design new optoelectronics that can surpass the fundamental limitations on their conventional semiconductor counterparts. Herein, a novel 2D h-BN/p-MoTe 2 / graphene/n-SnS 2 /h-BN p-g-n junction, fabricated by a layer-by-layer dry transfer, demonstrates high-sensitivity, broadband photodetection at room temperature. The combination of the MoTe 2 and SnS 2 of complementary bandgaps, and the graphene interlayer provides a unique vdW heterostructure with a vertical built-in electric field for high-efficiency broadband light absorption, exciton dissociation, and carrier transfer. The graphene interlayer plays a critical role in enhancing sensitivity and broadening the spectral range. An optimized device containing 5−7-layer graphene has been achieved and shows an extraordinary responsivity exceeding 2600 A W −1 with fast photoresponse and specific detectivity up to ≈10 13 Jones in the ultraviolet-visible-near-infrared spectrum. This result suggests that the vdW p-g-n junctions containing multiple photoactive TMDs can provide a viable approach toward future ultrahigh-sensitivity and broadband photonic detectors.

InSe (bandgap of ~1.20 to 1.80 eV depended on thickness reduction from bulk to monolayer). Specifically, the uncooled SWIR detectivity is up to ~10 14 Jones at 1064 nm and ~10 12 Jones at 1550 nm, respectively. This result indicates that the 2DLMs vdW heterostructures with type-II band alignment produce an interlayer exciton transition, and this adventage can offer a viable strategy for devising high-performance optoelectronics in SWIR or even longer wavelengths beyond the individual limitations of the bandgaps and heteroepitaxy of the constituent atomic layers.

In article number https://doi.org/10.1002/adma.201805656, Rui Chen, Liyuan Zhang, Youpin Gong, and co‐workers develop an h‐BN/MoTe2/graphene/SnS2/h‐BN van der Waals heterostructure to realize an ultrahigh‐sensitivity broadband (405–1550 nm) photodetector, due to its unique advantages for high‐efficiency light absorption and exciton dissociation. Graphene plays a key role in enhancing the sensitivity and broadening the spectral range, providing a viable approach toward future ultrahigh sensitivity and broadband photodetectors.

Negative optical torque is a counterintuitive optomechanical phenomenon that can emerge in light-assembled nanoparticle (NP) clusters (i.e., optical matter) under circular polarization. However, in experiments, stable negative torque was limited to optical matter with 3 or more NPs. Here, we show that by increasing the particle size, the sign of optical torque can be reversed in optical matter dimers, where stable negative torque arises in dimers of 300 nm diameter Au or 490 nm diameter polystyrene NPs. Our computational analysis reveals that the multipolar resonances in large NPs can enhance the forward scattering along the spin angular momentum (SAM) direction of light, creating a recoil negative torque due to momentum conservation. The observation of stable negative torque in dimers pushes the limit to the smallest optical matter, demonstrating the universal existence of negative torque in such a system. The underlying principle also provides new strategies for making light-driven nanomotors.