Low refractive index OLEDs for practical high-efficiency outcoupling. Final report
- Pennsylvania State Univ., University Park, PA (United States); Penn State University
Improving OLED light extraction is a significant on-going challenge for the OLED lighting industry. The goal of this program was to explore the potential to improve internal light extraction in a manufacturable way by lowering the refractive index of the OLED stack through dilution with an electrically-inert, low refractive index molecule. We accomplished this goal, identifying a small molecule that can be co-evaporated in the hole transport layer of OLEDs at high loading to reduce the refractive index by 0.2-0.3 refractive index units without degrading charge transport. Implementing this dilution molecule in the hole transport layer of a range of single and multi-stack OLEDs, we demonstrated the ability to improve their internal light extraction by up to ~35% without increasing their drive voltage or reducing their operational lifetime. Importantly, these findings extend to state-of-the-art device architectures with proprietary OLED materials.
- Research Organization:
- Pennsylvania State Univ., University Park, PA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Building Technologies Office
- DOE Contract Number:
- EE0008717
- OSTI ID:
- 1877182
- Report Number(s):
- EE0008717-Final Report-111
- Country of Publication:
- United States
- Language:
- English