Investigating the Dynamics of Quantum Dot based Light-emitting Diodes with different emission wavelength

摘要

Colloidal quantum dots (QDs) have attracted significant interest because of their unique properties, such as high quantum efficiency, size-dependent emission wavelength, high color purity and low-cost solution processability. These properties make them one of the most promising emission materials for thin film light emitting diodes (LEDs) of the future. Although QD-LEDs have been in the focus of science for quite some time, many topics are still neglected, such as the dynamics, which expresses the switching speed for these LEDs. However, this knowledge could be crucial for the application of such LEDs in communication or sensor technology. This work will give an overview of the influence of the size of the QDs used and the associated emission wavelength. The particles used have cores of cadmium selenide (CdSe) of different sizes and are covered by shells of zinc sulfide (ZnS). The examined LEDs are constructed in the same way and differ only in the QDs used as emission layer. The dynamics of these samples were investigated by electro-optical measurements like Modulated Electroluminescence Spectroscopy (MELS) and Transient Electroluminescence Measurements (TEL). This work will show that the dynamics of LEDs increase with the core size of the QDs used. We assume that these results will mark the progress in the development and realization of faster QD LEDs.