Phenothiazinen-Dimesitylarylborane-Based Thermally Activated Delayed Fluorescence: High-Performance Non-doped OLEDs With Reduced Efficiency Roll-Off at High Luminescence

We report a phenothiazinen-dimesitylarylborane thermally activated delayed fluorescence (TADF) molecule that exhibits high external quantum efficiency (EQE) in non-doped organic light-emitting diodes (OLEDs) at high luminescence. The non-doped device shows green electroluminescence with an emission peak of 540 nm and a maximum EQE of 19.66% obtained at a luminescence of ~170 cd m−2. The EQE is still as high as 17.31% at a high luminescence of 1,500 cd m−2 with small efficiency roll-off