Enhanced Reverse Inter-System Crossing Process of Charge-Transfer Stated Induced by Carrier Balance in Exciplex-Type OLEDs

The reverse inter-system crossing (RISC, CT<sup>3</sup> → CT<sup>1</sup>) process in charge transfer (CT<sup>1</sup> and CT<sup>3</sup>) states is an effective approach to improving the energy utilization rate of excited states, precise control full use RISC have important scientific significance application prospect for fabricating realizing efficient exciplex-type organic light-emitting diodes (OLEDs). conventional OLEDs based on m-MTDATA: Bphen received extensive attention among researchers owing fact that difference between CT<sup>1</sup> around zero promotes occurrence process. But up now, only transient photoluminescence can infer existence experiment, which quite unfavorable comprehensive understanding this design high-performance OLEDs. Fortunately, paper, a series balanced unbalanced exciplex-based devices are prepared by changing donor-acceptor blending ratio emitting layer (<i>x</i>% <i>m</i>-MTDATA:<i>y</i>% Bphen; <i>x</i>%, <i>y</i>% weight percent) carrier density flowing through device. CT directly observed via analyzing fingerprint magneto-conductance (MC) traces device at room temperature, has higher electroluminescence (EL) efficiency than Specifically, low-field MC curves show (ISC) line shape, whereas those from exciplex present shape low bias-current conversion into ISC with further increase bias current. transition attributed triplet-charge annihilation (TQA) caused excessive carries under high Combining physical microscopic mechanism device, above-mentioned various be explained as follows: same current, extra holes or electrons generated emitter due mismatch molecular concentrations. These superfluous will react state, aggravates TQA weakens state participates. That say, there strong weak Contrarily, beneficial delayed fluorescence, resulting its EL This work not deepens influence balance devices, but also paves way designing highly OLED fully employing