In recent years, fully inorganic copper-based chalcogenide materials have gradually become a research hotspot in the field of novel optoelectronic devices due to their high stability, lead-free and low toxicity, and excellent optoelectronic properties. Compared with traditional lead-containing based chalcogenides, fully inorganic copper-based chalcogenides have significant advantages in terms of environmental friendliness and long-term stability, and thus are widely recognised as potential candidates for next-generation high-performance optoelectronic materials. Among many copper-based chalcogenides, Cs?Cu?Br?, as a typical fully inorganic copper-based chalcogenide, has received extensive attention from domestic and foreign research teams for its excellent environmental stability and good optoelectronic performance. According to the current reports, it is known that most of the preparation methods of Cs?Cu?Br? materials use the solution method. However, the films prepared by the solution method often have a large number of holes, which seriously affects the photoelectric properties of the films. These holes not only reduce the optical uniformity and crystalline quality of the films, but also may introduce surface defects, which in turn lead to a significant degradation of the device performance. Therefore, choosing an appropriate film growth method becomes one of the keys to enhance the performance of Cs?Cu?Br? films. For this reason, finding methods that can effectively reduce holes and improve the densification of thin films has become the focus of research. The aim of this work is to obtain high quality Cs?Cu?Br? films by optimizing the film growth process. In the study, Cs?Cu?Br? thin films were prepared on silicon substrates by vacuum thermal evaporation, and the effects of the growth temperature on the film morphology, crystalline quality and optical properties were systematically investigated. Vacuum thermal evaporation, as a physical vapor deposition method, can effectively improve the crystallinity and surface flatness of the films by controlling the deposition rate and substrate temperature. In this study, it was found that the growth temperature had a significant effect on the quality of Cs?Cu?Br? films. Under the optimal conditions, the prepared Cs?Cu?Br? thin films exhibited excellent morphological characteristics, with a flat and dense film surface, very few holes, and good crystallinity. In addition, the films exhibit strong absorption in the deep ultraviolet region (270 nm) and are capable of emitting bright blue light (460 nm), which indicates that the films have excellent optical properties. The optical band gap of the films is 4.31 eV, which meets the requirements for deep-UV photovoltaic applications. Based on the optimally grown high-quality Cs?Cu?Br? films, Cs?Cu?Br?/n-Si heterojunction photodetectors were further prepared in this study. The heterojunction photodetector exhibits a remarkable photoresponse in the deep-ultraviolet band (270 nm), with a response rate of 0.47 mA/W, corresponding to a detection rate of 2.09×10? Jones.This result indicates that the photoelectricity performance of Cu-based chalcogenides can be significantly enhanced by optimizing the growth process of the films, thus providing new possibilities for their application in deep-ultraviolet photodetection. It is shown that Cs?Cu?Br? thin films not only excel in stability and lead-free environmental friendliness, but also exhibit high potential for application in deep-ultraviolet photodetectors. In this study, a new method for the preparation of high-performance Cs?Cu?Br? thin films based on vacuum thermal evaporation technology is proposed, and the morphology and optoelectronic properties of the films are significantly improved by systematically regulating the growth temperature. This not only provides an effective way for the preparation of silicon-based Cs?Cu?Br? thin films, but also lays the foundation for the development of high-performance Cu-based deep-ultraviolet photodetectors. This research result is of great significance for the wide application of lead-free and environmentally friendly chalcogenide materials in optoelectronic devices in the future.