Impact of light-matter coupling strength on the efficiency of microcavity OLEDs: A unified quantum master equation approach

TL;DR

This paper develops a unified quantum master equation model to analyze how different light-matter coupling regimes in microcavity OLEDs affect their efficiency, addressing challenges like triplet accumulation and efficiency roll-off.

Contribution

It introduces a comprehensive quantum model that systematically compares weak and strong coupling effects on OLED performance.

Findings

Strong coupling can modify exciton-photon dynamics to improve efficiency.

Weak coupling enhances radiative decay via the Purcell effect.

Optimal coupling regime depends on device-specific parameters.

Abstract

Controlling light-matter interactions is emerging as a powerful strategy to enhance the performance of organic light-emitting diodes (OLEDs). By embedding the emissive layer in planar microcavities or other modified optical environments, excitons can couple to photonic modes, enabling new regimes of device operation. In the weak-coupling regime, the Purcell effect can accelerate radiative decay, while in the strong-coupling regime, excitons and photons hybridize to form entirely new energy eigenstates with altered dynamics. These effects offer potential solutions to key challenges in OLEDs, such as triplet accumulation and efficiency roll-off, yet demonstrations in the strong-coupling case remain sparse and modest. To systematically understand and optimize photodynamics across the different coupling regimes, we develop a unified quantum master equation model for microcavity OLEDs. The model is then applied to estimate device performance in the different coupling regimes to determine which one is the best.