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The antimony selenide thin film solar cells technology becomes promising due to its excellent anisotropic charge transport and brilliant light absorption capability. Especially, the device performance heavily relies on the vertically oriented Sb₂Se₃grain to promote photoexcited carrier transport. However, crystalline orientation control has been a major issue in Sb₂Se₃thin film solar cells. Herein, a new strategy has been developed to tailor the crystal growth of Sb₂Se₃ribbons perpendicular to the substrate by using the structural heterostructured CdS buffer layer. The heterostructured CdS buffer layer is formed by a dual layer of CdS nanorods and nanoparticles. The hexagonal CdS nanorods passivated by a thin cubic CdS nanoparticle layer can promote [211] and [221] directional growth of Sb₂Se₃ribbons using a close space sublimation approach. The improved buffer/absorber interface, reduced interface defects, and recombination loss contribute to the improved device efficiency of 7.16%. This new structural heterostructured CdS buffer layer can regulate Sb₂Se₃nanoribbons crystal growth and pave the way to further improve the low‐dimensional chalcogenide thin film solar cell efficiency.

Antimony selenide (Sb₂Se₃) has excellent directional optical and electronic behaviors due to its quasi‐1D nanoribbons structure. The photovoltaic performance of Sb₂Se₃solar cells largely depends on the orientation of the nanoribbons. It is desired to grow these Sb₂Se₃ribbons normal to the substrate to enhance photoexcited carrier transport. Therefore, it is necessary to develop a strategy for the vertical growth of Sb₂Se₃nanoribbons to achieve high‐efficiency solar cells. Since antimony sulfide (Sb₂S₃) and Sb₂Se₃are from the same space group (Pbnm) and have the same crystal structure, herein an ultrathin layer (≈20 nm) of Sb₂S₃has been used to assist the vertical growth of Sb₂Se₃nanoribbons to improve the overall efficiency of Sb₂Se₃solar cell. The Sb₂S₃thin layer deposited by the hydrothermal process helps the Sb₂Se₃ribbons grow normal to the substrate and increases the efficiency from 5.65% to 7.44% through the improvement of all solar cell parameters. This work is expected to open a new direction to tailor the Sb₂Se₃grain growth and further develop the Sb₂Se₃solar cell in the future.