The Study of Blocking Effect of Nb2O5 in Dye-Sensitized Solar Cells under Low Power Lighting

Abstract

Suppression of charge recombination is an efficient strategy capable of improving the photovoltaic performance of dye-sensitized solar cells (DSSCs). Herein, we fabricate a Nb2O5 thin film on a fluorine-doped tin oxide (FTO) photoanode using a facile dip-coating method and study its blocking effect on charge recombination under various illuminance. The results show that the blocking effect of Nb2O5 is strongly illuminance intensity dependent. The blocking effect of Nb2O5 is insignificant at strong (one sun, >100,000 lux) illumination because the suppressed reverse charge flux makes no substantial contribution to the high-level injection of photo-excited charges. Conversely, the blocking effect plays an important role in the efficiency improvement as the photon-injected charge flux significantly reduces at low-intensity illumination (300–6000 lux). The efficiency of DSSCs with a blocking layer can be improved by 10% to 53% under low-intensity illumination, and the efficiency improvement is attributed to an improvement in fill factor.