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

Abstract

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 (η) of the optimized Al-doped SnO₂ DSSCs is enhanced by 75%. After being treated with TiCl₄, the highest η of DSSCs based on Al-doped SnO₂ nanocrystals is approximately 6.91%, which is a high overall photoconversion efficiency for SnO₂-based DSSCs.