Affiliation:
1. Samsung Display Corporation Yongin South Korea
2. Samsung Electronics Yokohama Japan
Abstract
Blue phosphorescent materials typically have larger capacitance compared with commercialized blue fluorescent OLEDs. To improve capacitance‐related image quality issues, we need to reduce capacitance of devices without sacrificing other device's properties such as efficiency, lifetime, and operating voltage. In this study, we analyzed devices with phosphor sensitized TADF (PST) emission devices by impedance spectroscopy and revealed that the capacitance is largely affected by giant surface potential (GSP) of consisting layers. The influence of GSP on capacitance is sensitively changed by not only GSP value but also the position of GSP layers in the device. We revealed the effect of GSP of HTL, BIL etc. and explained the mechanism underlying on this phenomena based on device simulation.