Preparation of nano-flower-like SnO2 particles and their applications in efficient CdS quantum dots sensitized solar cells

Two kinds of hierarchical SnO 2 particles as nano-flower-like SnO 2 particles (NF-SnO 2 ) and mesoporous-sphere-like SnO 2 particles (MS-SnO 2 ) have been synthesized and used in CdS quantum dots (QDs) sensitized solar cells (QDSSC). TEM images show that NF-SnO 2 particles compose well interconnected nanoplates and MS-SnO 2 spheres are consisted with large numbers of SnO 2 nanoparticles with size about 7 nm. Owing to the larger Brunauer–Emmett–Teller surface area of NF-SnO 2 particles, NF-SnO 2 photoelectrode can load higher amounts of CdS QDs and shows enhanced light absorbance, resulting in higher short-circuit current density compared with that of MS-SnO 2 photoelectrode. The electrochemical impedance spectroscopy analysis results show that the QDSSC with NF-SnO 2 photoelectrode has a higher charge recombination resistance and a longer electron lifetime, so its photovoltaic performance is better than that of the QDSSC with MS-SnO 2 photoelectrode. The QDSSC with NF-SnO 2 photoelectrode can attain 3 % power conversion efficiency, which is higher than that of the cell with MS-SnO 2 photoelectrode (1.97 %).