In addition to the synthesis and characterization of fluorescent emitter systems based on conjugated polymers we have developed phosphorescent polymer materials. Here, the active components of a phosphorescent system - triplet emitter, hole- and electron transport molecules - can be linked as a side group to a polystyrene main chain.
By varying the molecular structures of the side groups as well as the composition of the side chains with respect to the triplet emitter, hole- and electron transport structure, and by blending with suitable glass-forming, so-called small molecules, brightness, efficiency and lifetime of the produced OLEDs can be optimized. Compared to fluorescent polymer systems they are increased significantly.
By choosing the triplet emitter, such as iridium complexes, different emission colors can be specifically set. The use of side-group polystyrenes as matrix has several advantages:
- almost unlimited usability of molecular structures which are already studied and known from the vacuum processing of OLEDs
- variable miscibility of different molecules and molecular compositions
- achievement of sufficiently high glass transition temperatures
- simple processability from common solvents in printing technology
Using appropriate reactive comonomers, crosslinking reactions are performed in the processed polymer film, which subsequently allow the construction of multi-layer systems processed from solution.