The Application of Heterostructured SrTiO₃-TiO₂Nanotube Arrays in Dye-Sensitized Solar Cells

Heterostructured SrTiO 3 -TiO 2 nanotube arrays (ST-TNTAs) on fluoride doped SnO 2 conductive glass (FTO) were synthesized through a three-step in-situ hydrothermal reaction. TiO 2 nanotubes in ST-TNTAs vertically grew on the FTO substrate in single crystallized rutile phase, while SrTiO 3 grains in cubic perovskite phase dispersed evenly on the surface of TiO 2 . The sandwich shaped all-solid-state dye-sensitized solar cells (DSSCs) were assembled with TiO 2 nanorods, nanotubes and ST-TNTAs as the photoanode, respectively. Once SrTiO 3 deposited, the position of Fermi level of the composited semiconductor raised, resulting in the increase of open circuit voltage ( V OC ). Meanwhile, both short-circuit current density ( J SC ) and photoelectrical conversion efficiency ( η ) increased first and then decreased with the amount of SrTiO 3 . In comparison to TiO 2 nanorods and nanotubes, ST-TNTAs demonstrated the highest photoelectrical conversion efficiency (5.42%) under the irradiation of solar simulator and external quantum efficiency (EQE) at visible region, and also the lowest electron transfer resistance, which further proved that SrTiO 3 acted as a good medium for electron transfer between TiO 2 and photosensitizer. As a result, both the increased surface area of the nanotube relative to the nanorod and the matched bandgap structure in the composited structure of TiO 2 and SrTiO 3 improve the performance of the DSSCs.