Achieving a 32% EQE solution-processed simple structure OLED via exciplex system

Abstract

Exciton generation and charge balance play a dominant character in organic light-emitting diode (OLED). Performance concerning power management is a crucial requirement in consumer electronics. Improving exciton generation requires key considerations, such as excellent intermolecular charge transfer and high predisposition for effective electron-hole recombination in suitable energy levels with high delayed fluorescent quantum yield and reduced non-radiative decay. Forming exciplex by physically blending with suitable material provides the feasibility in tailoring the parameters mentioned above for effectively improving the exciton generation. Herein, we comprehensively study the exciplex forming host by blending the carbazole-based hole transporting material BCC-36 with triazine-based materials PO-T2T, and 3P-T2T as electron transporting material designed and investigated. Developed exciplex formation host showed a high photoluminescent quantum yield of 90% with prolonged emission, representing our exciplex system with good TADF ability. Thus, effective utilization of non-radiative triplet excitons via reverse intersystem crossing results in high device performance with a maximum external quantum efficiency (EQE) of 20% and the current efficacy of 41 cd A−1 by using the exciplex system as a sole emitter. In addition, the high-performing exciplex system was investigated as a co-host for conventional fluorescent (C545T), phosphorescent (Ir(ppy)2(acac)) and TADF (4CzIPN) compounds as the emitters are utilized for high-efficiency OLEDs. Remarkably, the corresponding doped device system showed a high EQE of 12.5 % (C545T), 32.5% (Ir(ppy)2(acac)) and 26.5% (4CzIPN) under optimized solution-processed device conditions.