Correlation between ion impurity in thermally activated delayed fluorescence organic light-emitting diode materials and device lifetime

We propose a measurement method of ion impurity amounts of thermally activated delayed fluorescence (TADF) green dopant powders in a solution by applying a triangle voltage waveform and measuring a small displacement current that has been developed for screening and optimization of materials for thin-film transistor-liquid crystal displays (TFT-LCDs). We found that there is a strong correlation between ion impurity and organic light-emitting diode (OLED) lifetime, and we confirmed that the TADF green dopant, having a large number of ion impurity, has short OLED lifetime.