We demonstrate that voltage-independent and highly efficient white light-emitting diodes (WLED) can be obtained based on phosphorescent dye-doped conjugated polymer blend films. Conjugated polymers are used as the blue and green emitters, as well as the energy host, and a phosphorescent dye is used as the red emitter and guest material. The phase-separation between the conjugated polymers is suppressed by blending miscible polymer and copolymer having the same moiety. Therefore, we expect that efficient Förster-type energy transfer occurs through this homogeneous morphology. By introducing the copolymer into the emissive layer to enhance its miscibility, we obtained a voltage-invariant white emission from the polymeric LEDs. The luminous efficiency of the WLED with the single active layer is increased dramatically by introducing the phosphorescent dopant as a red emitter.
Bibliographical noteFunding Information:
This work was supported by ERC grant of National Research Foundation (NRF) funded by the Korea Ministry of Education, Science and Technology (MEST) (No. R11-2007-045-01002-0(2009) ). It was also partially supported by a Grant (code #: 2010k000345 ) from ‘Center for Nanostructured Materials Technology’ under ‘21st Century Frontier R&D Programs’ of the Ministry of Education, Science and Technology, South Korea.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Materials Chemistry
- Electrical and Electronic Engineering