Due to the novel optical and optoelectronic properties, two dimensional (2D) materials have received increasing interests for optoelectronics applications. Discovering new properties and functionalities of 2D materials are challenging yet promising. Here broadband polarization sensitive photodetectors based on few layer ReS 2 are demonstrated. The transistor based on few layer ReS 2 shows an n-type behavior with the mobility of about 40 cm 2 V -1 s -1 and on/off ratio of 10 5 . The polarization dependence of photoresponse is ascribed to the unique anisotropic in-plane crystal structure, consistent with the optical absorption 2 anisotropy. The linear dichroic photodetection with a high photoresponsivity reported here demonstrates a route to exploit the intrinsic anisotropy of 2D materials and the possibility to open up new ways for the applications of 2D materials for light polarization detection.

The dynamic processing of optoelectronic signals carrying temporal and sequential information is critical to various machine learning applications including language processing and computer vision. Despite extensive efforts to emulate the visual cortex of human brain, large energy/time overhead and extra hardware costs are incurred by the physically separated sensing, memory, and processing units. The challenge is further intensified by the tedious training of conventional recurrent neural networks for edge deployment. Here, we report in-sensor reservoir computing for language learning. High dimensionality, nonlinearity, and fading memory for the in-sensor reservoir were achieved via two-dimensional memristors based on tin sulfide (SnS), uniquely having dual-type defect states associated with Sn and S vacancies. Our in-sensor reservoir computing demonstrates an accuracy of 91% to classify short sentences of language, thus shedding light on a low training cost and the real-time solution for processing temporal and sequential signals for machine learning applications at the edge.

Organic–inorganic heterostructures are an emerging topic that is very interesting for optoelectronics. Here, non‐conventional p–n junctions are investigated using organic rubrene single crystal and 2D MoS2 as the p‐ and n‐type semiconducting materials, respectively. The current‐rectifying behavior is clearly observed in the junction device. The rectification ratio can be electrically tuned by the gate voltage due to the 2D nature of the heterostructure. The devices also show good photoresponse properties with a photoresponsivity of ≈500 mA W−1 and a fast response time. These findings suggest a new route to facilitate the design of nanoelectronic and optoelectronic devices based on layered inorganics and organics.

Background: The Covid-19 pandemic restricts children and adolescents from doing normal daily activities such as playing outdoors and going to school. The incidence and prevalence of myopia have increased during the COVID-19 pandemic. The aim of this study was to investigate and evaluate the impact of the home confinement during the COVID-19 pandemic on the progression of myopia among children and adolescents in Chongqing, China.Methods: The survey was conducted by using stratified samplings. Samples were randomly selected from the 2019 National Student Physique and Health Survey database, and their visual function and refractive data were compared with those in 2020. Vision-related behavior questionnaire including digital screen exposure was applied to investigate the correlation between eye parameter and eye health-related behavior.Results: A total of 1,733 and 1,728 students were enrolled in 2020 and 2019, respectively. The percentage of myopia students was 55.02% in 2020, which was higher than that in 2019 (44.62%). The mean uncorrected visual acuity (UCVA, LogMAR, 0.35 ± 0.42) in 2020 was higher than that in 2019 (0.27 ± 0.36, P < 0.001). The mean spherical equivalent (SE) refraction (−1.94 ± 2.13 D) in 2020 was lower than that in 2019 (−1.64 ± 5.49 D, P < 0.001). For students who used digital devices for online courses, the mean SE in the television group (−1.10 ± 1.49 D) was better than that in the computer group (−2.03 ± 2.37 D, P = 0.0017) and in the cell phone group (−2.02 ± 2.09 D, P = 0.0028). The average duration of online classes (r = −0.27, P < 0.0001), the number of online classes per day (r = −0.33, P < 0.0001), as well as digital screen exposure time (r = −0.20, P < 0.0001) were negatively correlated with SE, and the average time of outdoor activity (r = 0.20, P < 0.0001) was positively correlated with SE.Conclusions: Increased digital screen exposure contributes to myopic progression in children and adolescents of Chongqing during the COVID-19 pandemic. Suitable digital devices should be provided for online classes and outdoor activity should be advocated to prevent myopic pandemic.

We report the fabrication of single-crystal monolayer WxMo1−xS2 alloy triangles using chemical vapor deposition method. Raman and photoluminescence property are investigated in correlation to the composition. In the monolayer triangles, the photoluminescence peak shifts continuously from 687.4 nm at the triangle center to 633.6 nm at the edge, corresponding to a switch from MoS2 to WS2 across the heterojunction. This composition-graded alloy may have interesting functions in broadband photodetection and multi-color light emission.