Environmentally friendly synthesis of quantum dots and their applications in diverse fields from the perspective of environmental compliance: A review

Semiconductor Quantum-dots (QDs), characterized by their unique optoelectronic tunability, high efficiency, and multifunctionality, have emerged as transformative materials in diverse fields, including display technologies, energy conversion, solar cells, biomedical applications, and quantum technologies. With ongoing advancements in material synthesis and device engineering, the application scope of QDs is anticipated to expand further, thereby driving interdisciplinary technological innovations and fostering breakthroughs across multiple scientific fields. However, in recent years, the rapid development of Cd, Pb, and Hg-based QDs has raised significant environmental and biological concerns due to the inherent toxicity of these heavy metals. Consequently, these materials have been classified as restricted substances by major global entities, including international organizations, the European Union, and the United States, through international treaties and domestic legislation. To mitigate legal risks associated with environmental pollution, the development of non-toxic and environmentally friendly (eco-friendly) QDs has become imperative. This review focuses on several eco-friendly QDs, such as indium phosphide (InP), copper indium sulfide (CuInS₂), and graphene QDs (GQDs), from the perspective of environmental compliance. It comprehensively discusses their synthesis methods, application domains, and the advantages and disadvantages of different preparation techniques, along with their environmental impacts. Finally, the review summarizes the existing challenges, limitations, and potential solutions for the development of environmentally benign QDs.