Red, phosphorescent OLEDs: New, bipolar materials, photophysical characterization, charge transport and OLED optimization

• Applicants: Dr. Dirk Hertel; Professorin Dr. Elisabeth Holder; Professor Dr. Klaus Meerholz; Professor Dr. Nikolaus Risch
• Subject Area: Experimental and Theoretical Physics of Polymers
• Term: from 2008 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 64059274

Light-emitting diodes consisting of wide bandgap semiconducting oligomers and polymers combined with phosphorescent, red light-emitting metal-ligand complexes offer favorable perspectives in display technology as well as in large area colored lighting applications. The advantages result through a combination of low cost, wet-chemical processability with a highly efficient and pure, red emission color, which is of importance to the development of e.g. full color large area flat panel displays for television - and personal computer screens or as red colored lighting panels. This joint project addresses the development of smart combinations of wide bandgap semiconducting oligomers and polymers that are blended with phosphorescent red light-emitting iridium(lll) and osmium(ll) metal-ligand complexes. The ligand design of these complexes is such that electron and hole transporting moieties are connected to the chelating units and thus are interacting with these highly conjugated ligand systems that will be directly attached to the metal core. This design is allowing efficient charge recombination at the phosphorescent species expected to result in more efficient, color pure, red light emission of the triplet systems. Investigation and optimization of energy transfer, charge generation and transport in these material compositions will be carried out, being of beneficial impact towards the design of improved and highly efficient, saturated red light-emitting diodes.

• DFG Programme: Research Grants