Selective Microwave Absorption by Trioctyl Phosphine Selenide: Does It Play a Role in Producing Multiple Sized Quantum Dots in a Single Reaction?

Chemical transformations carried out under MW (microwave) irradiation often produce unexpected rate enhancements because of selective MW absorption by the reactants in the solution. We demonstrate unprecedented control over nucleation, growth, and Ostwald ripening in the formation of CdSe quantum dots (QDs), the quintessential quantum dot. The selectivity of the MW reactions is demonstrated by the ability to generate multiple, different sized QDs in the same reaction, where each QD component exhibits 6−7% size dispersity. The number of QDs in solution translates to color saturation (intensity), and the size of the QD translates to color index and is completely controlled by temperature and concentration in the MW reaction. The ability to repetitively generate nucleation and growth events in which a specific color index with defined color saturation is isolated from a single reaction offers potential for preparing mixed QD compositions for applications in optical bar-coding, white light emitting diodes (LEDs), and photovoltaics (PVs).