Two-dimensional (2D) bismuth oxychalcogenide (Bi2O2X, X refers to S, Se, and Te) is one type of rising semiconductor with excellent electrical transport properties, high photoresponse, and good air stability. However, the research on 2D Bi2O2S is limited. In this work, ultrathin Bi2O2S nanosheets are synthesized by a facile and eco-friendly chemical synthesis method at room temperature. The thickness and lateral sizes are 2–4 nm and 20–40 nm, respectively. The 2D ultrathin Bi2O2S nanosheets have a broad absorption spectrum from ultraviolet (UV) to near-infrared (NIR). Photoelectrochemical (PEC) photodetectors based on 2D Bi2O2S nanosheets are fabricated by a simple drop-casting method. The 2D Bi2O2S-based PEC photodetectors show excellent photodetection performance with a broad photoresponse spectrum from 365 to 850 nm, a high responsivity of 13.0 mA/W, ultrafast response times of 10/45 ms, and good long-term stability at a bias voltage of 0.6 V, which are superior to most 2D material-based PEC photodetectors. Further, the 2D Bi2O2S PEC photodetector can function as a high-performance self-powered broadband photodetector. Moreover, the photoresponse performance can be effectively tuned by the concentration and the kind of electrolyte. Our results demonstrate that 2D Bi2O2S nanosheets hold great promise for application in high-performance optoelectronic devices.

Zn-doped SnO 2 nanocrystals were successfully synthesized by a simple hydrothermal method. It is found that Zn doping into SnO 2 can induce a negative shift in the flat-band potential (V FB ) and increase the isoelectric point. As a result, dye-sensitized solar cells (DSCs) based on Zn-doped SnO 2 nanocrystal photoanodes exhibit longer electron lifetimes and higher dye loading compared to undoped SnO 2 based DSCs. The overall power conversion efficiency (h) of the optimized Zn-doped SnO 2 based DSC reaches 4.18% and increases to 7.70% after the TiCl 4 treatment. More importantly, a remarkable h of 8.23% is achieved for DSCs based on a high-quality double-layer SnO 2 photoanode with the TiCl 4 treatment, to the best of our knowledge, which is so far the best reported efficiency for DSCs based on SnO 2 photoanodes. † Electronic supplementary information (ESI) available: The pH-dependent zeta-potential of the undoped and Zn-doped SnO 2 nanoparticles; J-V characteristics of the undoped and Zn-doped SnO 2 based cells measured in the dark; J-V characteristics of the undoped and Zn-doped SnO 2 based cells with the TiCl 4 treatment; comparison of the photovoltaic performance of the DSCs based on SnO 2 photoanodes with various morphologies; Plots of lifetime of photoinjected electrons in the DSCs based on undoped and Zn-doped SnO 2 photoanodes with TiCl 4 treatment as a function of charge; FESEM image of SnO 2 spheres. SeeFig. 3 XPS high-resolution spectra of undoped and Zn-doped SnO 2 nanoparticles: (a) Sn 3d, (b) O 1s, and (c) Zn 2p peaks.This journal is

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Ultraviolet photodetectors (UV PDs) have attracted extensive attention owing to their wide applications, such as optical communication, missile tracking, and fire warning. Wide-bandgap metal-oxide semiconductor materials have become the focus of high-performance UV PD development owing to their unique photoelectric properties and good stability. Compared with other wide-bandgap materials, studies on indium oxide (In2O3)-based photoelectrochemical (PEC) UV PDs are rare. In this work, we explore the photoresponse of In2O3-based PEC UV PDs for the first time. In2O3 microrods (MRs) were synthesized by a hydrothermal method with subsequent annealing. In2O3 MR PEC PDs have good UV photoresponse, showing a high responsivity of 21.19 mA/W and high specific detectivity of 2.03 × 1010 Jones, which surpass most aqueous-type PEC UV PDs. Moreover, In2O3 MR PEC PDs have good multicycle and long-term stability irradiated by 365 nm. Our results prove that In2O3 holds great promise in high-performance PEC UV PDs.

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Al-doped ZnO has attracted much attention as a transparent electrode. The graphene-like ZnO monolayer as a two-dimensional nanostructure material shows exceptional properties compared to bulk ZnO. Here, through first-principle calculations, we found that the transparency in the visible light region of Al-doped ZnO monolayer is significantly enhanced compared to the bulk counterpart. In particular, the 12.5 at% Al-doped ZnO monolayer exhibits the highest visible transmittance of above 99%. Further, the electrical conductivity of the ZnO monolayer is enhanced as a result of Al doping, which also occurred in the bulk system. Our results suggest that Al-doped ZnO monolayer is a promising transparent conducting electrode for nanoscale optoelectronic device applications.

A novel photoelectrochemical self-powered ultraviolet photodetector (UVPD) has been assembled employing Ag@SiO2 core–shell nanoparticles (NPs) incorporated TiO2 nanocubes (NCs) as the photoanode. The incorporation of the plasmonic core–shell NPs can boost the photocurrent of the self-powered UVPD. Finite difference time domain (FDTD) and transient absorption spectroscopy (TAS) were employed to understand plasmonic enhancement processes. By optimizing the incorporated ratio of Ag@SiO2 NPs, the photocurrent of UVPD with 2 wt % Ag@SiO2 NPs reaches the maximum value in view of the enhanced light harvesting and effective inhibition of charge recombination. More importantly, the UVPD with 2 wt % Ag@SiO2 NPs achieves a high on/off ratio of 8212 and a remarkable responsivity of 0.151 A W–1, combined with a rapid response time, prominent spectral selectivity, and photosensitivity linearity response.

Vertically aligned rutile TiO2 nanowire arrays (NWAs) with lengths of ∼44 μm have been successfully synthesized on transparent, conductive fluorine-doped tin oxide (FTO) glass by a facile one-step solvothermal method. The length and wire-to-wire distance of NWAs can be controlled by adjusting the ethanol content in the reaction solution. By employing optimized rutile TiO2 NWAs for dye-sensitized solar cells (DSCs), a remarkable power conversion efficiency (PCE) of 8.9% is achieved. Moreover, in combination with a light-scattering layer, the performance of a rutile TiO2 NWAs based DSC can be further enhanced, reaching an impressive PCE of 9.6%, which is the highest efficiency for rutile TiO2 NWA based DSCs so far.