Reducing Spontaneous Orientational Polarization via Semiconductor Dilution Improves OLED Efficiency and Lifetime
Emmanuel O. Afolayan, İbrahim Dursun, Chao Lang, Evgeny Pakhomenko, Marina Kondakova, Michael Boroson, Michael A. Hickner, Russell J. Holmes, Noel C. Giebink
Abstract
The spontaneous alignment of molecular dipoles that occurs in many organic light-emitting diodes (OLEDs) is known to blunt their performance, but is not easy to control within a given device stack. This study shows that coevaporating a small amount of polyethylene in the electron-transport layer of an OLED dramatically reduces the spontaneous orientational polarization, leading to increased device efficiency and lifetime due to decreased exciton-polaron annihilation in the emissive layer. This result highlights the potential of semiconductor dilution to improve OLED performance, and provides a new means to understand exciton-polaron-driven degradation in blue OLEDs.