Comparative study of multi-functional luminogens with 1,3,5-triazine as the core and phenothiazine or phenoxy donors as the peripheral moieties for non-doped/doped fluorescent and red phosphorescent OLEDs

Abstract

A series of three-armed fluorescent emitters based on a 1,3,5-triazine acceptor as the central core and phenothiazine or phenoxy moieties as the different peripheral units, are designed and synthesized. All of them exhibit aggregation-induced emission enhancement and thermally activated delayed fluorescence. Photoluminescence quantum yields exceeded 37 and 67% for non-doped and doped solid-state samples respectively. The compounds were found to be capable of transporting both holes and electrons. The highest mobility values of more than 1 × 10−4 cm2V−1s−1 were obtained for the compound having three phenothiazine moieties at electric field of more than 1 × 106 Vcm−1. Additionally, three types of organic light emitting diodes based on these materials were fabricated. The device containing non-doped emission layer with the compound containing single phenothiazine moiety as the emitter gave maximum external quantum efficiency of 5.4%. The device with doped emission layer containing 5% solid solution of the compound having three phenothiazine moieties in an appropriate host gave maximum external quantum efficiency of 9.9%. The phosphorescent device hosted by the compound with single phenothiazine unit exhibited maximum external quantum efficiency of 10.3% and a low-efficiency roll-offs of 1% at 1000 cd/m2.