Nanostructured Wide Bandgap Semiconductors (NWBS) are supposed to be one of the candidate materials for manufacturing ultraviolet photodetectors (UVPDs) with excellent performance. Recently, different nanostructured ZnO was applied in UVPDs, which has been reported to possess outstanding advantages for UV detection and attract extensive research. Although some significant progress has been reported in the research of UVPDs, there are still other problems needs to be drawn more attention. For example, the electron depletion layer will be caused by the oxygen adsorption on the surface of ZnO, which could reduce the electron concentration. This review begins with machining methods of different nanostructured ZnO (e.g. ZnO nanowires (NWs), nanorods (NRs), microtubes, nanoparticles (NPs), nanoneedles and film) and then the detection mechanism of the UVPDs is also introduced. In addition, UVPDs assembled with core structure mentioned show different photoelectric properties in this review, mainly including responsivity, on/off ratio, and response time. Finally, the development trend of UVPDs research and its application prospect are prospected.

A self-powered photodetector (PD) based on n-type ZnO/p-type small-molecule copper(II) phthalocyanine (CuPc) inorganic/organic heterojunction film deposited on FTO substrate was constructed by simple solution spin-coating and thermal evaporation technology. The designed heterojunction device exhibits typical photoresponse behavior under zero bias, indicating that the device possesses a self-powered characteristic. This may benefit from the formation of a built-in electric field in the heterojunction, which can effectively separate electron–hole pairs. Specifically, the optimal performances of the device appear at a wavelength of 365 nm and light intensity of 0.03 mW cm⁻², achieving on/off ratio of ∼245.88 (29.88), responsivity (R_p) of ∼227.11 mA W⁻¹ (0.39 mA W⁻¹), detectivity (D*) of ∼7.63 × 10¹¹ Jones (∼7.53 × 10⁹ Jones) and EQE of ∼77.23% (0.14%) at +2 V (0 V) bias voltage. In addition, the device has potential application in weak light detection. Therefore, the construction of inorganic/organic heterojunctions may provide a feasible strategy for the development of high-performance, self-powered and wavelength-selective PDs.

The optimized metal-semiconductor-metal (MSM) ultraviolet photodetector (UVPD) based on ZnO/MXene/ZnO (ZMZ) sandwich structure is reported here. Since introducing ZMZ, the photoelectric performance of the UVPD has increased, which benefited from the cooperation between the interface electron depletion layer and injection of hot electrons (HEs), triggering the “storage and ejection” behavior of electrons. In general, under 365-nm laser illumination (6.25 mW/cm $^{\text{2}}$ ), the Responsivity ( $\textit{R}_{\textit{p}}$ ) and Detectivity ( $\textit{D}^{\ast}$ ) are almost unexpectedly increased by approximately an order of magnitude compared with pristine ZnO-based UVPD. More specifically, the ON/OFF ratio, $\textit{R}_{\textit{p}}$ , and $\textit{D}^{\ast}$ are about $>$ 10 $^{\text{3}}$ , 25.48 mA/W, and $>$ 10 $^{\text{11}}$ Jones, respectively. Further, the long-term stable performance of the flexible ZMZ-based UVPD can also be observed after the 1000th bending cycle. And especially, the maximum attenuation coefficient (AC) of photocurrent is only $\sim$ 5.75%. This work may offer a meaningful strategy for designing and improving the performance of ZnO-based UVPD in the future.

The development and free distribution of global land cover (GLC) products have greatly assisted in the evolution and analysis of relationships between land cover and landscape pattern. In this study, GlobCover and MCD12Q1 GLC datasets of 2005 and 2009 were comparatively used to analyze the variation of land cover in Anhui Province, China at both the class and landscape scale. The land cover classification schemes of both datasets were firstly reclassified to six types of forestland, grassland, wetland, cropland, artificial area, and others, and then FRAGSTATS was used to calculate the landscape indices. The results showed that from 2005 to 2009, the area density of ‘cropland’ landscape decreased, and it increased for ‘wetland’ and ‘artificial area’. The landscape fragmentation of ‘forestland’ and ‘grassland’ were larger. Moreover, over the same period, the class edge (CE) of ‘cropland’ was diminished; while the CE of ‘wetland’ was enhanced and the aggregation became larger. Conversely, the aggregation and shape complexity of ‘artificial area’ remained the same. The clumpiness index (CLUMPY) of ‘cropland’ varied from 0.8995 to 0.9050, indicating a higher aggregation and more concentrated distribution. The heterogeneity index (HT) value of MCD12Q1 and GlobCover datasets varied, respectively, from 0.9642 to 0.9053 and from 0.8867 to 0.8751, demonstrating that the landscape heterogeneity of Anhui Province was reduced from 2005 to 2009. Driving force analysis (DFA) was just performed for ‘artificial area’, ‘cropland’, and ‘wetland’ according to the 2005–2009 statistical yearbook data, because they were apt to be affected by human activities over a relatively short period of time.

In this paper, a performance-enhanced hybrid ultraviolet metal–semiconductor–metal photodetector (UVPD) has been produced. This device incorporates a mixed photosensitive layer consisting of MXene nanoflakes that are covered on a thin film formed by Ag nanowires (NWs) wrapped in ZnO nanoparticles. This configuration, referred to as ZnO@Ag NWs/Mxene, capitalizes on the hot electrons generated by the localized surface plasmon resonance phenomenon occurring in the Ag NWs and MXene. These hot electrons possess sufficient energy to traverse the interface depletion layer and reach the ZnO layer. Therefore, the injected hot electrons serve as additional photo carriers in the ZnO layer, thereby increasing the number of photo-generated carriers and improving the carrier concentration in ZnO. The improved UVPD device exhibits an amplified photocurrent of ∼2499.35 nA at 5 V, under a light intensity of 6.52 mW cm⁻² and a wavelength of 365 nm. Simultaneously, it achieves enhanced performance indices, including an On/Off ratio of ∼984.19, a responsivity (R _p) of ∼66.87 mA W⁻¹, and a detectivity (D ^*) of ∼1.82 × 10¹¹ jones. These values represent a significant improvement compared to devices based solely on the ZnO configuration, with enhancements of ∼24.90, 3.93, 23.38, and 9.33 times, respectively. Based on the obtained results, it can be inferred that employing the hot electron injection effect to design and enhance the performance of optoelectronic devices based on wide band gap semiconductors is a reasonable and effective strategy.