Halide perovskites have attracted worldwide attention in recent years due to their fundamental scientific importance and practical applications in energy harvesting fields. However, its toxicity and instability are hindering the commercial applications of halide perovskite-based devices. Recently discovered inorganic lead-free Cs₂AgBiBr₆ double perovskite exhibits excellent optical and electronic properties and can be considered as a candidate for photovoltaic devices. In this work, we report the photoelectric performance of the Cs₂AgBiBr₆ single crystal as a photodetector both macro- and microscopically. By utilizing a nanoscale probe as a top electrode, it is discovered that the photogenerated carriers are effectively collected, as in the case of macroscopic electrodes. More importantly, the photocurrent is enhanced as the applied nanoscale mechanical load increases, which indicates that the local bandgap of the Cs₂AgBiBr₆ single crystal decreases with the increased nanoscale stress, showing similar tendency with the first-principles calculation result. The reported finding establishes a strategy to enhance the performance of photodetectors, which will be a great help in improving the performance of future optoelectronic devices and energy harvesting devices at the nanoscale.

Fluorine dopant inhibited the oxidation process in CsSnI_3−xF_x films with high carrier concentration, low resistivity and wide light absorption.

Research on the preparation and performance of graphene composite materials has become a hotspot due to the excellent electrical and mechanical properties of graphene. Among such composite materials, zinc oxide/graphene (ZnO/graphene) composite films are an active research topic. Therefore, in this study, we used the vacuum thermal evaporation technique at different evaporation voltages to fabricate an amorphous ZnO/graphene composite film on a flexible polyethylene terephthalate (PET). The amorphous ZnO/graphene composite film inherited the great transparency of the graphene within the visible spectrum. Moreover, its electrical properties were better than those of pure ZnO but less than those of graphene, which is not consistent with the original theoretical research (wherein the performance of the composite films was better than that of ZnO film and slightly lower than that of graphene). For example, the bulk free charge carrier concentrations of the composite films (0.13, 1.36, and 0.47 × 10¹⁸ cm⁻³ corresponding to composite films with thicknesses of 40, 75, and 160 nm) were remarkably lower than that of the bare graphene (964 × 10¹⁸ cm⁻³) and better than that of the ZnO (0.10 × 10¹⁸ cm⁻³). The underlying mechanism for the abnormal electrical performance was further demonstrated by X-ray photoelectron spectroscopy (XPS) detection and first-principles calculations. The analysis found that chemical bonds were formed between the oxide (O) of amorphous ZnO and the carbon (C) of graphene and that the transfer of the π electrons was restricted by C=O and C-O-C bonds. Given the above, this study further clarifies the mechanism affecting the photoelectric properties of amorphous composite films.

A novel SAM (β-Th-2PACz) is developed as a hole-selective layer for perovskite solar cells, which outperformed its α-thiophene counterpart.