Highly crystallized ZnO–Ga2O3 core–shell heterostructure microwire is synthesized by a simple one‐step chemical vapor deposition method, and constructed into a self‐powered solar‐blind (200–280 nm) photodetector with a sharp cutoff wavelength at 266 nm. The device shows an ultrahigh responsivity (9.7 mA W−1) at 251 nm with a high UV/visible rejection ratio (R251 nm/R400 nm) of 6.9 × 102 under zero bias. The self‐powered device has a fast response speed with rise time shorter than 100 µs and decay time of 900 µs, respectively. The ultrahigh responsivity, high UV/visible rejection ratio, and fast response speed make it highly suitable in practical self‐powered solar‐blind detection. Additinoally, this microstructure heterojunction design method would provide a new approach to realize the high‐performance self‐powered photodetectors.

Solar radiation, especially ultraviolet (UV) light, is a major hazard for most skin-related cancers. The growing needs for wearable health monitoring systems call for a high-performance real-time UV sensor to prevent skin diseases caused by excess UV exposure. To this end, here a novel self-powered p-CuZnS/n-TiO UV photodetector (PD) with high performance is successfully developed (responsivity of 2.54 mA W at 0 V toward 300 nm). Moreover, by effectively replacing the Ti foil with a thin Ti wire for the anodization process, the conventional planar rigid device is artfully turned into a fiber-shaped flexible and wearable one. The fiber-shaped device shows an outstanding responsivity of 640 A W , external quantum efficiency of 2.3 × 10 %, and photocurrent of ≈4 mA at 3 V, exceeding those of most current UV PDs. Its ultrahigh photocurrent enables it to be easily integrated with commercial electronics to function as a real-time monitor system. Thus, the first real-time wearable UV radiation sensor that reads out ambient UV power density and transmits data to smart phones via wifi is demonstrated. This work not only presents a promising wearable health monitor, but also provides a general strategy for designing and fabricating smart wearable electronic devices.

Self‐powered ultraviolet (UV) photodetectors, which have vast applications in the military and for civilian purposes, have become particularly attractive in recent years due to their advantages of high sensitivity, ultrasmall size, and low power consumption. In particular, self‐powered UV photodetectors driven by a built‐in electric field cannot only detect UV signals but also be powered by the incident signals instead of external power. In this concept, the key issues and most recent developments on photovoltaic type UV photodetectors driven by p–n homojunction, heterojunction, and Schottky junction are surveyed. This should generate extensive interest in this field and encourage more researchers to engage in and tackle the scientific challenges.

A high responsivity self-powered solar-blind deep UV (DUV) photodetector with high rejection ratio was proposed based on inorganic/organic hybrid p–n junction. Owing to the high crystallized β-Ga2O3 and excellent transparent conductive polymer PEDOT:PSS, the device exhibited ultrahigh responsivity of 2.6 A/W at 245 nm with a sharp cutoff wavelength at 255 nm without any power supply. The responsivity is much larger than that of previous solar-blind DUV photodetectors. Moreover, the device exhibited an ultrahigh solar-blind/UV rejection ratio (R 245 nm/R 280 nm) of 103, which is two orders of magnitude larger than the average value reported in Ga2O3-based solar-blind photodetectors. In addition, the photodetector shows a narrow bandpass response of only 17 nm in width. This work might be of great value in developing a high wavelength selective DUV photodetector with respect to low cost for future energy-efficient photoelectric devices.

Self-powered solar-blind UV photodetector based on β-Ga2O3/polyaniline core–shell heterojunction with high detectivity (D* = 1.5 × 1011 Jones) and high Rpeak/R400 rejection ratio (3 × 102).

With unique ability to concentrate and manipulate light at nanoscale, surface plasmon resonance technologies create additional opportunities for fabricating superintegration photodetectors with desirable functionalities. To gain an insight into the state-of-the-art of plasmonic photodetectors, recent advances in novel devices as well as potential building blocks are presented herein. The article focuses particularly on understanding the enhancement mechanism of different architectures such as nanoparticles, gratings, waveguides, antennas, and microcavities. Meanwhile, challenges and potential design schemes are proposed in this inspiring field.

to the long chemical readsorption process (oxygen molecules readsorption) occurred at the surface. [10,11] In contrast, the photo voltaic PDs including p-n homojunctions, p-n heterojunctions, and Schottky barrier diodes show a fast response speed and a possible selfpowered function due to the photovoltaic effect. Furthermore, as there is an increasing emphasis on low energy consumption, selfpowered PDs which can operate without an external power source are particularly appealing in applications like submarine oil leakage monitoring and forest fires prevention. [12] Thus, researchers are highly motivated to develop highperformance UV PDs with selfpowered characteristics.Thanks to the continuous innovations in semiconductor technology, various widebandgap materials such as diamond, ZnO, TiO 2 , ZnS, etc., have drawn great attention in the field of UV PDs. [13][14][15][16] Among them, SnO 2 , a conventional metal oxide with a direct bandgap, is generally regarded as a ntype material in its undoped form because of the intrinsic defects. It possesses unique chemical, electrical, and optoelectronic properties, thus having vast applications in gas sensors, transparent conductors, and optoelectronic devices. [17][18][19] In particular, with a wide bandgap of ≈3.6 eV (at 300 K), SnO 2 exhibits good UV light absorption characteristics and high vis ible light transparency, making it an ideal candidate for UV PD, especially under acidic or alkalic circumstances in comparison with ZnO. [20] Up to now, various efforts have been devoted to demonstrate the excellent UV photosensitivity of SnO 2 . Previ ously, our group presented thin SnO 2 nanowire UV PDs with a high external quantum efficiency. [21] Chen et al. [22] fabricated monolayer SnO 2 nanonets with a high UV photocurrent. Tian et al. [23] reported ZnOSnO 2 heterojunction nanofibers with a high UV photodark current ratio. However, the response time of the works mentioned above is still dissatisfactory, of which the decay time is >50 s, [22] ≈50 s, [21] and 7.8 s, [23] respectively. Recently, Ling et al. [24] constructed a SnO 2 nanoparticle thin film/ SiO 2 /pSi heterojunction, which exhibited a short response time (<0.1 s) and a high UV photocurrent (≈4.0 × 10 −5 A), however, it suffered from a low photosensitivity (≈40) due to the high dark current. Thus, a combination of a high photosensitivity and a fast response speed has not been realized in SnO 2 PDs, not to men tion additional functions including selfpowered property and flexibility.Herein, a single-crystal SnO 2 microwire photodetector (PD) is demonstrated with a fast response speed owing to a low concentration of point defects. However, the presence of surface defects (e.g., oxygen vacancies) still limits its optoelectronic performance. To further improve the photoresponse of such device, a core-shell p-n junction is constructed by simply coating a new p-type transparent conductive (CuS) 0.35 :(ZnS) 0.65 nanocomposite film (CuZnS) on n-type SnO 2 microwire. As a result, not only the surface of SnO 2 is modified...

A facile chemical bath method is adopted to grow bismuth oxychloride (BiOCl) nanosheet arrays on a piece of Cu foil (denoted as BiOCl-Cu) and isolated BiOCl nanosheets are collected by ultrasonication. A self-supporting BiOCl film is obtained by the removal of Cu foil. Photodetectors (PDs) based on these BiOCl materials are assembled and the effects of morphologies and electrode configurations on the photoelectric performance of these PDs are examined. The BiOCl nanosheet PD achieves high responsivities in the spectral range from 250 to 350 nm, while it presents quite a small photocurrent and slow response speed. The BiOCl film PD yields low photocurrents and near-unity on-off ratios, demonstrating poor photoelectric performance. The photocurrent of the BiOCl-Cu PD with both electrodes on the BiOCl film is much higher than those of these above-mentioned PDs, and the response times are fast. Meanwhile, the BiOCl-Cu PD with separate electrodes on the BiOCl film and Cu foil achieves even higher photocurrents and presents a self-powering characteristic, depicting the improved photodetecting performances induced by the specific morphology and distinct electrode configuration. These results would promote the applications of BiOCl nanostructures in the photoelectric devices.