Control of electronic properties of triphenylene by substitution

► We model influence of substitution on electronic properties of triphenylene based polycyclic aromatic hydrocarbons. ► Predictions are verified by spectroscopy. ► The singlet-triplet energy gap is tuned by up to 0.4 eV. ► Efficient Ir(III) doped phosphorescent organic light-emitting diodes (OLEDs) are demonstrated.