Abstract
In recent years, there is an urgent demand for high-performance ultraviolet photodetectors with high photosensitivity, fast responsivity, and excellent spectral selectivity. In this letter, we report a self-powered photoelectrochemical cell-type UV detector using the ZnO/ZnS core-shell nanorod array as the active photoanode and deionized water as the electrolyte. This photodetector demonstrates an excellent spectral selectivity and a rapid photoresponse time of about 0.04 s. And the maximum responsivity is more than 0.056 (A/W) at 340 nm, which shows an improvement of 180 % compared to detectors based on the bare ZnO nanorods. This improved photoresponsivity can be understood from the step-like band energy alignment of the ZnO/ZnS interface, which will accelerate the separation of photoexcited electron-hole pairs and improve the efficiency of the photodetector. Considering its uncomplicated low-cost fabrication process, and environment-friendly feature, this self-powered device is a promising candidate for UV detector application.
Highlights
Ultraviolet light has been widely used in secure spaceto-space communication, chemical sensing, environmental monitoring, and optoelectronic circuits [1–3]
Typical top and cross-section view field-emission scanning electron microscopy (FESEM) images of ZnO nanorod arrays are displayed in Fig. 1a, b, which clearly show that the hexagonal ZnO nanorod arrays are grown vertically on the fluorine-doped tin oxide (FTO) glass
After coating ZnS with two successive ionic layer adsorption and reaction (SILAR) cycles, the photoresponsivity is more than 0.03 A/W in the wavelength region from 320 to 390 nm. These results suggest that the ZnO/ZnS core-shell nanorod array is benefited to improve the photoresponsivity of selfpowered ultraviolet photodetector (SPUV-PD)
Summary
Ultraviolet light has been widely used in secure spaceto-space communication, chemical sensing, environmental monitoring, and optoelectronic circuits [1–3]. For most of these applications, it is very important to precisely measure and control UV light. This type of UV-PDs normally involves the absorption and desorption of oxygen in the air, both of which are slow processes This type of UV photoconductors typically requires an external bias as the driving force to prevent the recombination of photogenerated electron-hole pairs, which makes them difficult to operate in harsh environment. To address these problems, self-powered photodiode-type UV-PDs have been developed.
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