Enhanced bi-polaron hopping in Y3+ and Sr2+ co-doped BaSnO3 for improved photoanode performance in dye sensitized solar cells

Abstract

Photoanodes with high carrier mobility and suitable band energy level plays a seminal role in the efficiency of dye sensitized solar cells. Since the conventional TiO₂ experience severe carrier recombination, we demonstrate BaSnO₃ (BSO) as photoanode with considerable performance through aliovalent co-doping strategy. Indeed, substituting 3 % Y³⁺ and Sr²⁺ in Sn⁴⁺ and Ba²⁺ sites respectively increase the strain, as evident from XRD and Raman spectral analysis. Consequently, the phonon line-width of 3 % co-doped BSO has drastically decreased, indicating the minimum electron-phonon coupling. This facilitates the easy carrier hopping of the self-trapped carriers involved in the bipolarons of BSO, resulting in improved carrier mobility. Further, XPS reveals co-dopants substitution without disturbing the BSO lattice. In essential, the co-doping strategy helps to achieve a photo-conversion efficiency of 3.66 %, which is almost 300 % higher than previously reported value for the bare BSO. To our best knowledge, it is one of the earlier works which focus to minimize the carrier-phonon interactions in BSO for improved DSSC performance.