Charge-Carrier Dynamics and Exciton-Polaron Quenching Studied Using Simultaneous Observations of Displacement Current and Photoluminescence Intensity
Yutaka Noguchi, Kaito Ninomiya, and Katsuya Sato
The Journal of Physical Chemistry C Article ASAP
Understanding the charge distributions in the vicinity of the emission layer (EML) of an organic light-emitting diode (OLED) is crucial for improving device performance.
In this paper the researchers from Meiji University, Japan 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), they were 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 chargecarrier dynamics and EPQ properties. The results contribute to the optimization of OLED device performance, since EPQ is a key process involved in efficiency roll-off and device degradation.
The DCM curves for the CBP and TPBi host devices, respectively, were calculated using Setfos 5.2.