Unified Analysis of Transient Electroluminescence in Organic Light‐Emitting Diodes: Deciphering Charge Transport and Emission Dynamics

Abstract Understanding charge transport and recombination dynamics in organic light‐emitting diodes (OLEDs) is essential for improving their optoelectrical performance. Thus, this study investigates transient electroluminescence (Tr‐EL) in OLEDs using six phosphorescent emitters within both single‐host and exciplex‐host OLED systems. The Tr‐EL responses are categorized into three types: Initial overshoot, terminal overshoot, and negligible overshoot, each corresponding to distinct physical mechanisms, i.e., trap‐assisted release, charge redistribution, and efficient recombination, respectively. Time‐dependent drift‐diffusion simulations reproduce these behaviors and clarify the roles of mobility imbalance, interfacial accumulation, and trap density. 2D and 3D contour maps of the overshoot demonstrate a sharp, non‐monotonic dependence on carrier mobilities, enabling the prediction of charge imbalance and emission dynamics. This unified experimental–theoretical framework establishes Tr‐EL as a comprehensive diagnostic tool, guiding the rational design of OLEDs to suppress parasitic charge storage, enhance recombination balance, and improve optoelectrical performance.