This describes a carbozole-based host polymer for electro-phosphorescent OLED devices with balanced electron and hole transport, and which is solution-processible.
This is a new class of OLED (organic light emitting diode) host materials for use in flat panel displays for computer monitors and TV and for solid state lighting and back-lighting for liquid crystal displays.
The materials have the following advantages:
1. Compared to conventional OLED molecular materials, which must be vacuum-deposited into thin films, these materials, based on p-conjugated polymers and oligomers, may be coated from solution, which offers cost advantage and ease of scale-up to large-area thin films.
2. These materials have a high triplet energy and can be doped with electro-phosphorescent emitters, which have a quantum yield inherently 4 times higher than the electro-fluorescent emitters, used in conventional OLED materials.
3. These host materials are designed for long lifetimes. They have high glass transition temperatures, excellent morphological stability against crystallization and adjustable electron / hole mobilities to enable balanced charge injection and transport, which is critical to the lifetime of an OLED material.
4. Charge transporting of electrons and holes is balanced and provided within the hybrid carbozole-based molecules, not through blends of mixed hosts.