Owing to their high photoluminescence quantum yield, semiconductor nanocrystals (quantum dots) have recently been introduced for display applications. In a typical device, they are excited by the light of a blue or UV pump LED and function as an optical down converter to produce green and red light for covering a large color gamut. In contrast to these optically pumped systems, the direct electrical excitation of nanocrystal light emitters, i.e. electroluminescence, is an emerging field with many unresolved questions.
A key challenge is the simultaneous need for large fluorescent quantum yields enabled by effective surface passivation in conjunction with high charge carrier mobilities in the nanocrystal layer, which requires the passivating layer to be as thin as possible. This research project explores the benefits of coupled organic-inorganic nanocrystals for electroluminescent lighting applications, which exhibit a dense, yet conductive passivating layer of organic pi-systems. A central objective is the utilization of heavy metal-free materials to comply with EU regulations and work towards environmentally benign lighting solutions.
The project is carried out as part of a consortium consisting of six partners from industry (Merck KGaA and Osram), the Fraunhofer Society (Institute for Applied Polymer Sciences, Golm) as well as academia (LMU Munich, Uni Augsburg, Uni Oldenburg). Besides studying the isolated quantum materials and their optoelectronic properties, this project gears towards a detailed understanding of the fabrication and device aspects of quantum dot-based LEDs. As a proof of principle, a car taillight prototype made of such LEDs will be developed at the end of the project.
