Charge-Carrier Dynamics and Exciton-Polaron Quenching Studied Using Simultaneous Observations of Displacement Current and Photoluminescence Intensity

Herein, we propose a simple but powerful technique for investigating the correlations between the dynamics of charge carriers and excitons. This technique (DCM-PL) is based on displacement current measurement (DCM) with simultaneous observation of the photoluminescence (PL) intensity. By applying this technique to metal-insulator-semiconductor (MIS) devices incorporating a partial stack of a tris(2-phenylpyridine)iridium(III) [Ir(ppy)3]-based organic light-emitting diode (OLED), we are able to investigate the hole accumulation behavior and the corresponding PL losses due to exciton-polaron quenching (EPQ). Remarkably, the DCM-PL characteristics revealed that the polarity of the host material in the emission layer modifies the charge carrier dynamics and EPQ properties. Our results contribute to the optimization of OLED device performance, since EPQ is a key process involved in efficiency roll-off and device degradation.