Effect of N Dopant Amount on the Performance of Dye-Sensitized Solar Cells Based on N-Doped TiO2 Electrodes

We investigated the effect of varying amounts of N dopant on the performance of dye-sensitized solar cells (DSCs) based on the N-doped TiO2 electrodes. An interesting hierarchically macro-/mesoporous N-doped TiO2 structure with parallel macro-channels was formed by a simple template-free wet method. A series of N-doped TiO2 electrodes with varying N dopant amounts were fabricated for the DSCs. The N-doped DSCs achieve an overall conversion efficiency of 5.01-7.27%. The enhancement in the photocurrent density of N-doped DSCs was from 9% to 46% compared with undoped DSCs. The significantly enhanced photocurrent of the devices was found to be related to the N dopant amount and dye uptakes in N-doped TiO2 electrodes. The optimal N dopant amount for the N-doped TiO2 electrodes was 0.40%. Moreover, the charge transfer resistances demonstrated dependency on the N dopant amount. The electron lifetime of N-doped DSCs tended to decrease as the N dopant increased.