Highly luminescent ZnO quantum dots made in a nonthermal plasma

Nonthermal plasmas allow the preparation of ligand-free quantum dots combining high production rates with superior crystalline quality and luminescence properties. Here, ZnO quantum dots are produced in a radiofrequency capacitively-coupled plasma, exhibiting size dependent photoluminescent quantum yields up to 60% after air exposure - the highest reported to date for any compound semiconductor quantum dots prepared in the gas phase. Systematic studies indicate the importance of the surface for the observed luminescence behavior. The high luminescent quantum yields in the visible range of the spectrum and the ligand-free, scalable synthesis make these quantum dots good candidates for light emitting applications.