45‐4: Investigation of Triplet‐induced Annihilation in Phosphorescent and Thermally activated delayed fluorescent organic light‐emitting diodes

Abstract

Long‐lived triplets in phosphorescent organic light‐emitting diodes (PhOLEDs) and thermally activated delayed fluorescence (TADF) organic light‐emitting diodes (OLEDs) participate in triplet‐triplet annihilation and triplet‐polaron annihilation, dominantly deteriorating devices via defects serving as exciton quenchers. Although both PhOLEDs and TADF OLEDs suffer from the triplet exciton induced degradation mechanisms, detailed degradation processes are dissimilar in the two devices. Detailed degradation investigation of the PhOLEDs and TADF OLEDs was carried out by impedance spectroscopy and transient electroluminescence modeling, revealing that the triplet‐triplet annihilation is the main mechanism of degradation in the PhOLEDs, while triplet‐polaron annihilation is the major degradation route in the TADF OLEDs.