Control of electronic properties of triphenylene by substitution

We report a joint theoretical and experimental study of the electronic properties of triphenylene based polycyclic aromatic hydrocarbons. Their aggregation tendency is suppressed by phenyl- or diphenylamino-substitution. The influence of the substituents on the absorption properties is investigated by time-dependent density functional theory (TD-DFT). Upon chemical modification of the triphenylene core, the singlet–triplet energy gap can be reduced by up to 0.4eV. This prediction is spectroscopically verified. As a demonstration of the potential of these materials, Ir(III) doped phosphorescent organic light-emitting diodes (OLEDs) are tested, and limits of the performance are investigated. We achieve efficiencies above 30Cd/A for simple, green-emitting two layer devices.