Low-temperature synthesis of tin dioxide hollow nanospheres and their potential applications in dye-sensitized solar cells and photoelectrochemical type self-powered ultraviolet photodetectors

Abstract

Tin dioxide hollow nanospheres (SnO2 HNSs) are synthesized via a fast, template/surfactant-free and low-temperature (100 °C) solution route. These spheres consist of packed SnO2 nanocrystals, implying good intercrystal-line connections and effective light absorption. In view of these advantageous features inherited from the prepared SnO2 HNSs, TiO2 coated SnO2 HNSs (SnO2 HNS–TiO2) core–shell structures are used as photoanodes for dye-sensitized solar cells (DSSCs). A high power conversion efficiency (PCE) of 6.54% is achieved from SnO2 HNS–TiO2 DSSC, which increases by 53.8%, 21.5% and 330% as compared with those of the DSSCs based on commercial SnO2 nanoparticle-TiO2, TiO2 nanoparticle (P25) and SnO2 HNS, respectively. The unsensitized SnO2 HNS–TiO2 structure also serves as photoanode of the photoelectrochemical type ultraviolet (UV) photodetectors. The PCE of the SnO2 HNS–TiO2 based photodetectors reaches 21.5% at 330 nm, which is more than 2.75 times as large as that of nanocrystalline TiO2 film based UV photodetectors. Moreover, the self-powered UV photodetectors also exhibit a high responsivity of 0.837 A/W, a high on/off ratio of 4021, a rise time of 0.03 s and a decay time of 0.01 s for short-circuit current density signal under UV irradiation.