Spinner-Shaped Aggregation-Induced Emission Luminogens for Efficient Blue OLEDs

We have reported on spinner-shaped AIEE blue emitters, namely CTPE-PPI-PBA and CTPE-DPI-PBA, having a hybridized locally excited state (HLCT) state to harvest dark triplet excitons (Tn) via a high-lying reverse intersystem crossing (h RISC). The twisted structural conformation of these AIEE materials endows the blue emission in the film. Single-carrier device fabrication enabled both CTPE-PPI-PBA and CTPE-DPI-PBA to transport electrons and holes effectively due to proper E HOMO and E LUMO and to be employed as blue-emissive materials in OLEDs. All doped devices (CTPE-DPI-PBA:CBP) show a high exciton utilization efficiency (EUE) of 51% (8%), 52% (10%), and 76% (20%), respectively. The doped devices show a CE of 6.46, 6.92, and 7.88 cd/A, PE of 5.86, 5.93, and 6.56 lm/W, an EQE of 7.84, 7.90, and 8.98%, and a luminance of 5268, 5603, and 7803 cd/m2 at 8, 10, and 20%, respectively, with a CIE of (0.15, 0.09), (0.15, 0.09), and (0.15, 0.08), close to the NTSC standard. The doped (CTPE-DPI-PBA:CBP) devices show an insignificant roll-off efficiency due to exciton energy loss from the higher excited CTPE-DPI-PBA* to T1 excited CBP* (3.2 eV).