Preparation of ZnO and N Codoped TiO2 Porous Nanofibers for Dye-Sensitized Solar Cells

In this work, one-step electrostatic spinning and high-temperature calcination methods were used to synthesize TiO₂ composite nanofibers with porous morphology codoped with nitrogen and zinc oxide. The composite nanofibers were used as photoanode materials in dye-sensitized solar cells. The effect of doping with four different concentrations of nitrogen on the photoelectric conversion efficiency was explored in total. The results show that the DSSC assembled with the TZ-N3 photoanode has the highest energy conversion efficiency of 7.22% and a short-circuit current of 18.87 mA/cm², which is much higher than that of pure TiO₂ nanofibers as photoanode (4.75%). The improved photoconversion efficiency can be attributed to three aspects. First, the doping of ZnO formed a heterojunction, which enhanced the electron transfer efficiency and increased the open-circuit voltage. Second, the doping of nitrogen reduced the band gap width while oxygen vacancies appeared. This effectively prevents electron–hole complexation and enhances the short-circuit current. Finally, the specific surface area of the composite nanofibers with porous morphology increases. More attaching sites were provided for the dye molecules.