Red, Green, and Blue Microcavity Quantum Dot Light-Emitting Devices with Narrow Line Widths

Colloidal quantum dots (QDs) are tiny particles produced chemically from semiconductor materials with sizes below 100 nm. Because of the quantum size effect, QDs have very unique luminescent properties. Based on these light emitters, quantum dot light-emitting diodes (QLEDs) exhibit outstanding electroluminescence (EL) performances and they are promising for application in displays, light sources, and quantum-optoelectronic technologies. One of the greatest challenges in QLEDs is their low light outcoupling efficiency because of their planar structure, which limits the external quantum efficiency (EQE) of QLEDs for commercial applications. Here, we report the development of a set of red, green, and blue QLEDs with high EQE by incorporating microcavity structure in the devices. These microcavity devices exhibit modified EL spectra with full width at half-maximum of 12-14 nm. Red, green, and blue microcavity QLEDs show maximum current efficiency and maximum EQE of 96.5 cd A(-1) and 33.1%, 102 cd A(-1) and 24.7%, and 2.91 cd A(-1) and 11.2%, respectively. We anticipate that a suitable design of a microcavity combining superior QDs will lead to excellent EL performance of QLEDs for displays, ideal QLED-based single-photon sources for quantum information technology, and electrically pumped QD lasers.