Enhanced open-circuit voltage of dye-sensitized solar cells using Bi-doped TiO2 nanofibers as working electrode and scattering layer

Doping metal-ion into TiO2 materials is an effective method for enhancing the performance of dye sensitized solar cells (DSSCs). In order to develop materials that are easy to produce even in industrial quantities, we established a facile method by hydrothermal synthesis and subsequent heat treatment to prepare bismuth doped titanium dioxide nanofibers (Bi-doped TiO2 NFs). At first, we adopt Bi-doped TiO2 NFs as the working electrode to further study in DSSCs. Serving as working electrode, Bi-doped TiO2 NFs can remarkably improve open-circuit voltage (V-OC). The V-OC was significantly enhanced from 0.633 V to 0.800 V compared with pristine TiO2 does. However, this leads to a smaller J(SC) and a poorer overall performance for such devices. In order to improve the performance of DSSCs, we adopt Bidoped TiO2 NFs as the scattering layer of DSSCs, and various thicknesses of meso-TiO2 nanoparticles (meso-TiO2 NPs) were used as working electrode to increase the short-circuit current (J(SC)). The incorporated Bi-doped TiO2 NFs can help the electron transport and may reduce the possibility for electron-hole recombination. After optimizing the device's parameter, the overall performance of the meso-TiO2 NPs/Bi-doped TiO2 NFs devices was dominated by J(SC) until a maximum efficiency was attained with a mesa-TiO2 NPs thickness of 12 mu m. Such optimized DSSCs exhibited high open circuit voltage of 0.787 V, high fill factor of 78.2%, and high power conversion efficiency of 8.89%. (C) 2016 Elsevier Ltd. All rights reserved.