The Polymer Society of Korea

Abstract

To achieve highly stable organic light-emitting diodes (OLEDs), precise control of non-radiative transition processes involving triplet excitons is essential, particularly the suppression of Dexter energy transfer (DET). Although various molecular design strategies have been proposed to reduce DET-induced energy losses, direct and quantitative understanding of charge and exciton transition pathways under actual device operating conditions remains limited, hindering rational design for improved operational stability. Here, we investigate the dynamics of DET in phosphor-sensitized fluorescent (PSF) green OLEDs using transient absorption spectroscopy (TAS) and transient charge modulation spectroscopy (TCMS). By quantitatively analyzing non-radiative transition pathways related to the origin of instability, we identify the exciton dynamics governing operational instability. Based on these insights, we provide concrete molecular design guidelines for enhancing the stability of PSF-OLEDs.