High-Purity Selenium: Critical Advances in Chemical and Physical Purification

High-purity selenium (>5N) is an essential foundational material for next-generation photovoltaic, semiconductor, and biomedical applications. Nevertheless, industrial‑scale production faces severe constraints stemming from the trade‑offs among thermodynamic impurity‑removal limits, the high energy demand of physical refining, and the environmental toxicity of chemical routes. This work provides a systematic review and analysis of high-purity Se preparation technologies, categorizing existing processes into three main types: chemical, physical, and integrated hybrid methods, to address the key technical bottlenecks currently faced by the industry. By examining the thermodynamic mechanisms governing impurity separation in different purification routes, the study reveals the inherent limitations of standalone chemical or physical fractionation in achieving deep impurity removal. Furthermore, this research highlights the significant potential of hybrid processes that effectively combine chemical pretreatment with physical refinement. Such integrated approaches can synergistically enhance separation selectivity, process efficiency, and product purity, offering a breakthrough pathway toward the green and efficient production of high-purity Se. This work bridges the gap between laboratory breakthroughs and industrial implementation. It provides a definitive roadmap for the transition toward sustainable “ultrapure manufacturing,” offering guidance for the scalable, eco-friendly production of critical metals within the circular economy.