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The emergence of graphene has opened the prelude of extensive research on 2D layered materials. Especially, the diverse crystal structures and exceptional physical properties of multielement van der Waals semiconductors have provided a brand‐new platform for the implementation of novel optoelectronic devices. In this study, for the first time, the optoelectronic properties of a newly emerged quaternary van der Waals semiconductor, namely silver indium phosphorus sulfide (AgInP2S6), have been systematically investigated. It is revealed that the AgInP2S6 photodetector exhibits a fast response rate with the response/recovery time down to ≈1/2 ms. In addition, the AgInP2S6 device demonstrates stable photoswitching operation even under a high working temperature of up to 160 °C in the ambient environment without using any specific protection means, and the photoswitching characteristic is also well reserved after a 10‐h continuous heating at 150 °C in air. Profiting from the strong immunity to environmental thermal disturbance, a proof‐of‐concept high‐temperature optical communication application is demonstrated. In conclusion, this study provides an intriguing paradigm for the realization of the next‐generation optoelectronic devices against extreme working circumstances, which contributes to further broadening the scope of application of 2D material photodetectors in the upcoming future (e.g., space communication and tracking). [ABSTRACT FROM AUTHOR]

A van der Waals heterojunction photodetector has been constructed by vertically stacking a TaIrTe4 flake, a 2D type-II Weyl semimetal, and a WSe2 flake, a typical isotropic 2D semiconductor. Interestingly, the device exhibits a switchable operating mode depending on the direction of the voltage bias. Specifically, under a source-drain bias of −1 V, the device operates in a photovoltaic mode, featuring rapid response rate. Its response/recovery time is down to 22.5/25.1 ms, which is approximately one order of magnitude shorter than that of a pristine WSe2 photodetector (320/360 ms). In contrast, under a source-drain bias of +1 V, the device operates in a photoconductive mode with high photogain. The optimized responsivity reaches 9.1 A/W, and the corresponding external quantum efficiency and detectivity reach 2776% and 3.09 × 1012 Jones, respectively. Furthermore, the effective wavelength range of the TaIrTe4–WSe2 device has been extended to the long-wavelength region as compared to a WSe2 device. Beyond these, by virtue of the highly anisotropic crystal structure of TaIrTe4, the hybrid device exhibits polarized photosensitivity. Its anisotropy ratio reaches 1.72 (1.75) under a voltage bias of +1 (−1 V). On the whole, this research work provides a paradigm for the design and implementation of 2D materials based multifunctional optoelectronic devices. [ABSTRACT FROM AUTHOR]

The extensively explored unary and binary 2D layered materials (2DLMs) based photodetectors suffer from deficiencies of either poor stability, or indistinctive photoswitching, or poor scalability, or low durability to high‐temperature environment. Herein, a two‐step scenario, pulsed laser deposition (PLD) followed by post‐deposition annealing, is developed to produce centimeter‐scale 2D ZnIn2S4 (ZIS) nanofilms. Transport characterizations indicate that the as‐fabricated ZIS photodetectors manifest outstanding photosensitivity with an on/off switching ratio beyond 1000 upon 405 nm illumination. Beyond this, it is revealed that the photoresponse of the ZIS photodetectors increases with increasing channel thickness, where a responsivity of 1.4 A W−1, an external quantum efficiency of 430% and a detectivity of 9.8 × 109 Jones (1 Jones = 1 cm Hz1/2 W–1) are demonstrated with a pulse number of 10 000. In addition, these devices without encapsulation maintain stable within 1900 photoswitching cycles and over a one‐month storage in air. Furthermore, robust photoswitching is demonstrated under an operating temperature up to 150 °C. In summary, all these findings establish that PLD provides a powerful route to produce large‐scale multielement 2DLMs and the PLD‐derived ZIS photodetectors hold grand prospect for photoelectric technologies in specific high‐temperature environments (e.g., the lunar exploration program). [ABSTRACT FROM AUTHOR]

Low light absorption and limited carrier lifetime are two limiting factors hampering the further breakthrough of the performance of 2D materials (2DMs)‐based photodetectors. This study proposes an ingenious dielectric engineering strategy toward boosting the photosensitivity. Periodic dielectric structures (PDSs), including SiO2/h‐BN, SiO2/Al2O3, and SiO2/SrTiO3 (STO), are exploited to couple with 2D photosensitive channels (denoted as PDS‐2DMs). The responsivity, external quantum efficiency, and detectivity of an optimized SiO2/STO(300 nm)‐WSe2 photodetector reach 89081 A W−1, 2.7 × 107%, and 1.8 × 1013 Jones, respectively. These performance metrics are orders of magnitude higher than a pristine WSe2 photodetector, enabling reliable sub‐1 pW weak light detection. Based on systematic characterizations and first‐principle calculations, such dramatic performance improvement is associated with the promoted direct bandgap transition, reduced exciton binding energy, and PDS‐induced periodic intramolecular built‐in electric field across the atomically thin channels, which efficiently separates the photoexcited electron–hole pairs. More inspiringly, this strategy is also successfully exploited to 2D WS2 photodetectors, demonstrating broad applicability. As a whole, this work promises an exceptional avenue to ameliorate 2DM photodetectors and opens up a new horizon "dielectric optoelectronics," simultaneously highlighting the role of dielectric environment during analyzing the fundamentals of 2DM devices. [ABSTRACT FROM AUTHOR]

Low light absorption and limited carrier lifetime are critical obstacles inhibiting further performance improvement of 2D layered material (2DLM) based photodetectors, while scalable fabrication is an ongoing challenge prior to commercialization from the lab to market. Herein, wafer-scale SnS/ZIS hierarchical nanofilms, where out-of-plane SnS (O-SnS) is modified onto in-plane ZIS (I-ZIS), have been achieved by pulsed-laser deposition. The derived O-SnS/I-ZIS photodetector exhibits markedly boosted sensitivity as compared to a pristine ZIS device. The synergy of multiple functionalities contributes to the dramatic improvement, including the pronounced light-trapping effect of O-SnS by multiple scattering, the high-efficiency spatial separation of photogenerated electron-hole pairs by a type-II staggered band alignment and the promoted carrier transport enabled by the tailored electronic structure of ZIS. Of note, the unique architecture of O-SnS/I-ZIS can considerably expedite the carrier dynamics, where O-SnS promotes the electron transfer from SnS to ZIS whilst the I-ZIS enables high-speed electron circulation. In addition, the interlayer transition enables the bridging of the effective optical window to telecommunication wavelengths. Moreover, monolithic integration of arrayed devices with satisfactory device-to-device variability has been encompassed and a proof-of-concept imaging application is demonstrated. On the whole, this study depicts a fascinating functional coupling architecture toward implementing chip-scale integrated optoelectronics.