Charge-Carrier Dynamics and Exciton-Polaron Quenching Studied Using Simultaneous Observations of Displacement Current and Photoluminescence Intensity
Yutaka Noguchi, Kaito Ninomiya, Katsuya Sato
Abstract
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.