A facile method to prepare SnO2 nanotubes for use in efficient SnO2-TiO2 core-shell dye-sensitized solar cells

A high-efficiency photoelectrode for dye-sensitized solar cells (DSSCs) should combine the advantageous features of fast electron transport, slow interfacial electron recombination and large specific surface area. However, these three requirements usually cannot be achieved simultaneously in the present state-of-the-art research. Here we report a simple procedure to combine the three conflicting requirements by using porous SnO2 nanotube-TiO2 (SnO2 NT-TiO2) core-shell structured photoanodes for DSSCs. The SnO2 nanotubes are prepared by electrospinning of polyvinyl pyrrolidone (PVP)/tin dichloride dihydrate (SnCl2 center dot 2H(2)O) solution followed by direct sintering of the as-spun nanofibers. A possible evolution mechanism is proposed. The power conversion efficiency (PCE) value of the SnO2 NT-TiO2 core-shell structured DSSCs (similar to 5.11%) is above five times higher than that of SnO2 nanotube (SnO2 NT) DSSCs (similar to 0.99%). This PCE value is also higher than that of TiO2 nanoparticles (P25) DSSCs (similar to 4.82%), even though the amount of dye molecules adsorbed to the SnO2 NT-TiO2 photoanode is less than half of that in the P25 film. This simple procedure provides a new approach to achieve the three conflicting requirements simultaneously, which has been demonstrated as a promising strategy to obtain high-efficiency DSSCs.