Enhanced charge carrier transport via efficient grain conduction mode for Sb2Se3 solar cell applications

The combination of the SnO2 and Sb2Se3 offers an alternative strategy for realizing the n-p heterojunction in Sb2Se3 thin-film solar cells. However, the low conductivity of the SnO2 and the lateral growth of Sb2Se3 grains make carrier extraction more challenging, thereby resulting in unsatisfactory device performance. In this study, the improvement of the Sb2Se3 solar cell performance is achieved by enhancing the conductivity of the SnO2 and rearranging the Sb2Se3 elongated grains simultaneously so that the carriers can be efficiently transmitted through the grain conduction mode instead of the grain boundary conduction mode. Furthermore, the evolution of (Sb4Se6)n ribbons from pure lateral growth to longitudinal growth is observed by adjusting the distribution of doping elements on the SnO2 surface. Finally, under optimal treatment times, the carrier recombination in the heterojunction is effectively inhibited by building an efficient electron-transport channel, and the Sb2Se3 solar cell achieved the highest power conversion efficiency of 5.41%. Our study clarifies the relationship between carrier transport and grain orientation in one-dimensional Sb2Se3 materials and realized the effective adjustment of the (Sb4Se6)n ribbon growth direction. The outcomes of this study provide guidance for the control of carrier behavior in optoelectronic devices with similar one-dimensional absorber materials.