Abstract2D van der Waals (vdWs) heterostructure‐based multifunctional field effect transistor (FET) has brought about novel physical phenomena. Impressively, anti‐ambipolar characteristic is one of the basis logic functions being used in multi‐valued inverters, which is analogous to negative differential resistance (NDR)‐based transistor. Here, the tunable current‐transport and self‐driven optoelectrical properties of vertically stacked multilayer GeSe/SnS2 heterostructure are reported. In particular, it allows to be switched from n‐type‐dominant behavior to anti‐ambipolar operation regime (a large peak‐to‐valley ratio (PVR) of 1.5 × 103) as a result of different band‐bending under various bias. Under light‐doping engineering, the inverted V‐shaped peak is distinctly shifted because of the higher carrier recombination probability of p‐GeSe component. Besides, for photovoltaic performances, the device exhibits an ultralow dark current of ≈30 fA, a maximum responsivity of 130 mA W−1, and high Ion/Ioff ratio of ≈105 under 532 nm because of the large band offset and the efficient carrier separation process. Meanwhile, the polarization sensitivities can reach 1.9 at 405 nm and 2.6 at 635 nm. It is found that the polarity‐switchable behavior and self‐driven photodetection performance in GeSe/SnS2 vdWs FET can hopefully broaden and simplify the multifunctional integrated devices in the future.

P−N junctions are essential building blocks for electronic and optoelectronic devices and exhibit a wide range of applications in the field of photodetectors. In this work, high-performance self-powered photodetectors with spectral coverage ranging from the visible to near-infrared rrange (405−1310 nm) has been successfully fabricated by combining a p-type Ge 0.9 Sn 0.1 thin film with an n-type multilayered molybdenum disulfide (MoS 2 ) into a type-II band alignment. Benefiting from the great light absorption of the multilayer MoS 2 and the high in-plane mobility of the moderate Sn-doped Ge 0.9 Sn 0.1 film with a direct band gap, the constructed P−N heterojunction can effectively generate and separate the photogenerated carriers and lead to superior zero-biased photodetection performance. The device exhibited a fast response time of 200 μs, an ultralow dark current of ∼0.1 pA and high photoswitching ratio of ∼10 4 . In addition, the maximum values of photoresponsivity and detectivity are calculated to be 462 mA/W and 2.3 × 10 12 Jones, respectively. This work provides the new promising candidates for self-powered photodetectors toward broadband, fast speed, high sensitivity, and low power consumption. KEYWORDS: Ge 0.9 Sn 0.1 alloy, Molybdenum disulfide (MoS 2 ), van der Waals heterostructure, Self-driven photodetector, Broadband

Van der Waals (vdW) heterojunction has emerged as promising building blocks for the next generation of optoelectronics, which can fulfill the increasing demands of miniaturization, high density of integration, and low power consumption. The photovoltaic effect is one of the crucial functions for fast photo‐detection and energy‐harvesting applications. Here, graphene is integrated into vdW WS2/WSe2 heterojunction, the graphene can serve as electron and hole transport layers, boosting the collection efficiency of photo‐excited carriers and thus improving the photovoltaic effect. The graphene‐integrated device exhibits superior power‐conversion‐efficiency (PCE) up to 9.08%, one order of magnitude improvement compared to the device with metal‐WS2/WSe2‐metal configuration. Moreover, the back gate has great modulation on its photovoltaic effect due to the large gate‐tunability of band bending at the interface. Operating as self‐driven photo‐diode, it also achieves outstanding photodetection performance with high photo‐switching ratio of 1 × 106, high detectivity (D*) of 2.66 × 1012 Jones, and fast speed of 110 µs, all the parameters are improved by nearly one order of magnitude compared to the device without graphene integration. This work provides a universal approach by integrating graphene as vdW contact to significantly improve the photovoltaic effect and photodetection property toward highly efficient energy‐harvest and photodetector applications.