Solution-Processed Wide-Color-Tunable OLEDs from Green to Red with Multimixed Hosts Using an Aggregation-Induced TADF Emitter

A kind of solution-processed and multimixed-hosts organic light-emitting diodes (OLEDs) with wide color tunability from green to red was prepared by using a multifunctional thermally activated delayed fluorescence (TADF) material 10-(4-((4-(9H-carbazol-9-yl)-phenyl)sulfonyl)phenyl)-10H-phenoxazine (CzPXZ) with an aggregation-induced emission (AIE) feature. The emitting layers (EMLs) consist of a bulk heterojunction of 4,4 $'$ ,4 $''$ tris(carbazol-9-yl)triphenylamine (TCTA), 1,3-di (9H-carbazol-9-yl)benzene (MCP), and CzPXZ with a red phosphorescent emitter bis(1-phenyl-isoquinoline)-(acetylacetonato)iridium(III) (Ir(piq) $_{\text{2}}$ acac), and a wide range of color tunability from green to red is achieved by increasing the doping concentration of Ir(piq) $_{\text{2}}$ acac with CzPXZ transiting from a guest to host. When the doping concentration of Ir(piq) $_{\text{2}}$ acac is 0, 3, and 5 wt.%, the emitting color of the device is stable as green, orange, and red, respectively, but the emitting color of the device varies with the driving voltage clearly when the doping concentration is between 0.5 and 1 wt.%. The maximum external quantum efficiency (EQE $_{\text{max}}\text{)}$ of all the devices is up to 17.03%. The results demonstrate a simple method for preparing wide-color-tunable solution-processed OLEDs by using the multimixed hosts.