Enhancing the performance of dye-sensitized solar cells: doping SnO2 photoanodes with Al to simultaneously improve conduction band and electron lifetime

SnO2 is an important alternative to TiO2 for use as a semiconductor in dye-sensitized solar cell (DSSC) photoanodes. In this work, we prepared SnO2 and Al-doped SnO2 nanocrystals via a simple hydrothermal method, and found for the first time that the tuning of the conduction band and suppression of charge recombination are simultaneously improved in the Al-doped samples. The electron lifetime is significantly improved and the conduction band edge is shifted negatively by doping the SnO2 photoanode with Al. Compared to the undoped SnO2 DSSCs (AM 1.5, 100 mW cm(-2)), the power conversion efficiency (eta) of the optimized Al-doped SnO2 DSSCs is enhanced by 75%. After being treated with TiCl4, the highest eta of DSSCs based on Al-doped SnO2 nanocrystals is approximately 6.91%, which is a high overall photoconversion efficiency for SnO2-based DSSCs.