Cadmium selenide (CdSe) is an inorganic compound that commonly crystallizes in either the hexagonal wurtzite or cubic zincblende structure. This semiconductor material is particularly known for its strong quantum confinement effects, which make it a key ingredient in quantum dot technologies. With a bandgap of approximately 1.7 eV, CdSe exhibits strong optical absorption and photoluminescence in the visible range, making it an attractive material for light-emitting diodes, solar cells, and laser applications. Its optoelectronic properties can be finely tuned by altering the size and shape of CdSe nanoparticles, providing a versatile platform for a range of devices. While CdSe's properties make it a compelling choice for various applications, the use of cadmium, a toxic heavy metal, raises environmental and safety concerns that must be carefully managed. CdSe is often synthesized through colloidal methods, chemical vapor deposition, or molecular beam epitaxy, each offering different advantages in terms of crystal quality and control over material properties. The material remains a focus of ongoing research aimed at optimizing its favorable characteristics while addressing its environmental impact.