2021 Volume 60 Issue 6 Pages 615-630
Along with the development of organic light-emitting diodes (OLEDs), there has been continuous development of light amplification by stimulated emission of radiation (laser) technology based on organic materials over the last 30 years. Although indications of current injection lasing using organic materials have been reported by some groups, extensive studies must still be conducted with the aim of reducing the lasing threshold to provide a robust system that is resistant to high-power excitation. One of the major causes of the poor stability of existing systems is triplet accumulation. To address this issue, triplet excitons must be removed rapidly from the active device layers. This review focuses on a unique laser system composed of a lasing dye with a small singlet-triplet energy gap ΔEST and a triplet scavenging host that allows true continuous-wave (CW) organic lasing operation under optical pumping conditions. Furthermore, efficient suppression of the electroluminescence (EL) roll-off that occurs in OLEDs during high current injection is demonstrated, indicating the potential for application of this technology to organic semiconductor laser diodes (OSLDs).
