N-doped TiO2 applied in low-temperature-based dye-sensitized solar cells

With urea as nitrogen source, N-doped TiO₂ powders were synthesized and fabricated for low-temperature dye-sensitized solar cells (DSSCs) by the method of doctor-blade, and the highest temperature of the whole process was 120 °C. SEM, TEM, XRD, DRS, and XPS were used to analyze the microstructure of the N-doped TiO₂ powders. EIS, Bode plot, UV–Vis and I–V were employed to measure the photovoltaic performance of the DSSCs. The maximum photoelectric conversion efficiency (η) was 5.18 % when the amount of the doped nitrogen was 4 %, and, when compared with the η of 4.22 % for pure TiO₂, the short circuit current was increased by 22.2 % and the efficiency was increased by 22.7 %. It has been shown that the doped nitrogen could effectively suppress TiO₂ crystal phase transition from anatase to rutile, and decrease the size of particles. Therefore, the increased photoelectric conversion efficiency of the N-doped TiO₂-based DSSC was ascribed to the more suitable crystal phase, sizes and inner structure.