P‐217: Quantitative Investigation of High‐Temperature Degradation in Organic Light‐Emitting Diodes with Charge and Exciton Dynamics

We analyzed the causes of device efficiency and lifetime degradation with temperature increases in exciplex host‐based phosphorescent organic light‐emitting diodes (PhOLEDs). To investigate charge dynamics, capacitance‐voltage (C‐V) measurements and the fabrication of hole‐only devices (HOD) and electron‐only devices (EOD) were performed As a result, it was found that as the temperature increased, the hole mobility increased more significantly compared to the electron mobility. Additionally, through ordinary differential equation (ODE) simulations of transient photoluminescence (TrPL) andtransient electroluminescence (TrEL), we were able to quantify the exciton dynamics. As a result, the triplet‐triplet annihilation (TTA) rate constant of the host increased sharply with temperature increased to other rate constants, which was identified as the primary factor of the temperature‐induced reliability degradation.