Dresden 2026 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 15: Organic Semiconductors: Optics and Photonics

HL 15.6: Talk

Tuesday, March 10, 2026, 10:45–11:00, POT/0006

Direct Prediction of Organic Light-emitting Diode Efficiency Roll-off from Photophysical Parameters of Thermally Activated Delayed Fluorescence Emitters — •Kaiwen Guo, Yungui Li, and Paul Blom — Max Planck Institute for Polymer Research, Mainz, Germany

Severe efficiency roll-off significantly limits the practical performance of organic light-emitting diodes (OLEDs) at high luminance, especially for the devices based on thermally activated delayed fluorescence (TADF) emitters. Although numerous TADF emitters have been developed and investigated over last decade, in molecular scale the intrinsic molecular-origin of roll-off still remains unclear. In this work, we establish a direct correlation between device roll-off and intrinsic photophysical properties of TADF emitter, and analytically derive the roll-off as a function of exciton generation rate.

We propose an integrated methodology to extract complete set of photophysical parameters of TADF emitter, including the rates of exciton decays, spin conversion kinetics and bimolecular annihilation coefficients. Notably, we reveal that the roll-off behavior in TADF based OLED is not solely governed by bimolecular annihilation processes, but also influenced by the lifetime of delayed fluorescence. This knowledge enables us to predict the severity of roll-off directly from optical measurements and provides insight for further molecule designing.

Keywords: OLED; TADF; roll-off; photophysical parameters