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

Tin dioxide hollow nanospheres (SnO 2 HNSs) are synthesized via a fast, template/surfactant-free and low-temperature (100 °C) solution route. These spheres consist of packed SnO 2 nanocrystals, implying good intercrystal-line connections and effective light absorption. In view of these advantageous features inherited from the prepared SnO 2 HNSs, TiO 2 coated SnO 2 HNSs (SnO 2 HNS–TiO 2 ) 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 SnO 2 HNS–TiO 2 DSSC, which increases by 53.8%, 21.5% and 330% as compared with those of the DSSCs based on commercial SnO 2 nanoparticle-TiO 2 , TiO 2 nanoparticle (P25) and SnO 2 HNS, respectively. The unsensitized SnO 2 HNS–TiO 2 structure also serves as photoanode of the photoelectrochemical type ultraviolet (UV) photodetectors. The PCE of the SnO 2 HNS–TiO 2 based photodetectors reaches 21.5% at 330 nm, which is more than 2.75 times as large as that of nanocrystalline TiO 2 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. [ABSTRACT FROM AUTHOR]