[Display omitted] • The SnO 2 /Sb 2 Se 3 solar cell achieved the highest power conversion efficiency of 5.41%. • The carrier transport changes from grain-boundary conduction to grain conduction. • The evolution of (Sb 4 Se 6) n ribbons from lateral to longitudinal growth is detected. • The growth of Sb 2 Se 3 elongated grains is associated with that of (Sb 4 Se 6) n ribbons. The combination of the SnO 2 and Sb 2 Se 3 offers an alternative strategy for realizing the n-p heterojunction in Sb 2 Se 3 thin-film solar cells. However, the low conductivity of the SnO 2 and the lateral growth of Sb 2 Se 3 grains make carrier extraction more challenging, thereby resulting in unsatisfactory device performance. In this study, the improvement of the Sb 2 Se 3 solar cell performance is achieved by enhancing the conductivity of the SnO 2 and rearranging the Sb 2 Se 3 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 (Sb 4 Se 6) n ribbons from pure lateral growth to longitudinal growth is observed by adjusting the distribution of doping elements on the SnO 2 surface. Finally, under optimal treatment times, the carrier recombination in the heterojunction is effectively inhibited by building an efficient electron-transport channel, and the Sb 2 Se 3 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 Sb 2 Se 3 materials and realized the effective adjustment of the (Sb 4 Se 6) 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. [ABSTRACT FROM AUTHOR]