Hot‐Injection‐Free Silicon Nanocrystals Realize Record‐Breaking Sustainable QD LEDs

Silicon quantum dots (SiQDs) are an emerging class of high-performing, sustainable, environmentally safe luminescent nanomaterial. They offer opportunities for next-generation displays, solid-state lighting, medical applications, and quantum technologies. Here, we highlight recent breakthroughs in colloidal SiQD synthesis and photophysics, comparing eight synthetic strategies. Among these, we focus on the hydrogen silsesquioxane (HSQ) polymer route, a simple and cost-effective hot-injection-free method that yields highly crystalline, ultrabright, and stable SiQDs with photoluminescence quantum yields approaching 80%. We also describe how solvent engineering realizes SiQD light-emitting diodes (LEDs) with record external quantum efficiencies (EQEs, >16%), >700-fold-increased lifetimes, and far-red emissions to rival state-of-the-art perovskite QD LEDs. Moreover, rice husk-derived SiQD LEDs illustrate the potential for low-waste circular material cycles. Thus, SiQDs are a sustainable platform for plant growth technologies, photodynamic therapy, and beyond.