Efficient Nondoped Blue Fluorescent Organic Light-Emitting Diodes (OLEDs) with a High External Quantum Efficiency of 9.4% @ 1000 cd m-2 Based on Phenanthroimidazole-Anthracene Derivative

Organic light-emitting diodes (OLEDs) can promise flexible, light weight, energy conservation, and many other advantages for next-generation display and lighting applications. However, achieving efficient blue electroluminescence still remains a challenge. Though both phosphorescent and thermally activated delayed fluorescence materials can realize high-efficiency via effective triplet utilization, they need to be doped into appropriate host materials and often suffer from certain degree of efficiency roll-off. Therefore, developing efficient blue-emitting materials suitable for nondoped device with little efficiency roll-off is of great significance in terms of practical applications. Herein, a phenanthroimidazole-anthracene blue-emitting material is reported that can attain high efficiency at high luminescence in nondoped OLEDs. The maximum external quantum efficiency (EQE) of nondoped device is 9.44% which is acquired at the luminescence of 1000 cd m(-2). The EQE is still as high as 8.09% even the luminescence reaches 10 000 cd m(-2). The maximum luminescence is approximate to 57 000 cd m(-2). The electroluminescence (EL) spectrum shows an emission peak of 470 nm and the Commission International de L'Eclairage (CIE) coordinates is (0.14, 0.19) at the voltage of 7 V. To the best of the knowledge, this is among the best results of nondoped blue EL devices.