Principal Investigator Moungi Bawendi
We have resolved luminescence from individual colloidal CdSe/ZnS core/shell nanocrystals embedded in organic light emitting devices under laser and electrical excitation at room temperature. This work demonstrates that individual semiconductor nanocrystals can serve as emissive probes in organic optoelectronic devices and might be of interest as single photon sources.
Photoluminescence studies at low laser excitation power have shown that quantum dots behave as non-classical light sources. Electroluminescence from single quantum dots, which is more appealing for practical applications, has only been demonstrated recently at low temperature using self-assembled quantum dots grown by molecular beam epitaxy. In the recent study, we reported the demonstration of electroluminescence from single colloidal CdSe/ZnS (core/shell) nanocrystals embedded in organic light emitting device structures at room temperature. Spectral diffusion and blinking from individual quantum dots, key features of single quantum dots, were observed both in electro- and photoluminescence. We proposed a model in which the nanocrystals act as seeds for the formation of current channels that lead to enhanced exciton recombination in the vicinity of the quantum dots. Atomic force microscopy (AFM) studies on different layers of the device also support the model.