Quasi-one-dimensional van der Waals Sb2Se3 compound is a promising absorber material with desired optical properties and has theoretical potential to achieve high power conversion efficiency (PCE) of similar to 30%. Here, we report a new window layer, i.e., sputtered CdSe, which can enhance the Sb2Se3 device stability during light soaking and improve the photocurrent collection. Compared to the widely used CdS window layer, CdSe can suppress the interfacial diffusion between the window layer and the Sb2Se3 film, thereby reducing interfacial recombination sites. The dominant degradation mechanism in the CdS/Sb2Se3 devices is found to be the S diffusion instead of the Cd diffusion, as CdSe/Sb2Se3 devices did not show degradation during the 85 degrees C 120 h 1-Sun light soaking with similar Cd diffusion. Meanwhile, the enhanced photocurrent and reduced series resistivity in the CdSe/Sb2Se3 solar cells lead to an improved PCE of 4.5% with a glass/FTO/CdSe/Sb2Se3/graphite cell architecture. The obtained results suggest that CdSe can be employed as a window layer in the thin-film solar cells made of stable and efficient Sb2Se3-like quasi-one-dimensional van der Waals materials, providing a cost-effective way to integrate into the traditional thin-film solar cell manufacturing process.