Correlating Exciton Dynamics of Thermally Activated Delayed-Fluorescence Emitters to Efficiency Roll-Off in OLEDs

Monirul Hasan, Atul Shukla, Masashi Mamada, Chihaya Adachi, Shih Chun Lo, Ebinazar B. Namdas

Research output: Contribution to journalArticlepeer-review

Abstract

Physical parameters, such as decay rates and photoluminescence (PL) quantum efficiencies, associated with thermally activated delayed fluorescence (TADF) emitters play a critical role in determining the performance of organic light-emitting diodes (OLEDs). Herein, we investigate the impact of TADF decay rates and PL quantum efficiencies on external quantum efficiency (EQE) roll-off. Our analysis reveals that a high EQE with suppressed efficiency roll-off in TADF OLEDs can be achieved by shortening the delayed lifetime with an increasing delayed contribution or by shortening the prompt lifetime with increasing prompt contribution simultaneously. We further show that TADF compounds with long delayed and/or prompt lifetimes can give rise to multiple spin cycling and subsequently result in significant exciton quenching and efficiency roll-off in OLEDs. These results provide universal selection criteria for TADF emitters in OLEDs to concurrently achieve a high maximum EQE and low-efficiency roll-off.

Original languageEnglish
Article number054082
JournalPhysical Review Applied
Volume18
Issue number5
DOIs
Publication statusPublished - Nov 2022

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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