Vibronic singlet and triplet steady-state interplay emissions in phenazine-based 1,2,3-triazole films

Highlights: • Relatively high phosphorescent emission is achieved in phenazine derivatives. • Phosphorescence at room temperature occurs due to high intersystem crossing. • Steady-state phosphorescent emission is interpreted by double Arrhenius plot. • Deep energy barriers associated to aggregation effects in solid state films. • Potential use of purely organic phosphorescent material in optoelectronic devices. Photoluminescence and phosphorescence emissions of solid-state phenazine films were investigated in steady-state experimental conditions. Important discrepancies were observed for blended films where a host optically inert matrix was introduced to disperse the probe molecules. A vibronic spin-orbit phosphorescent emission clearly appeared, while for the films solely composed by the probe molecules, the phosphorescence broadened and presented a structureless shape, shifted to longer wavelengths. Further Arrhenius behavior analysis on the photoluminescent and phosphorescent emissions on temperature, corroborated the direct and reverse intersystem crossing interplay between singlet and triplet states. Molecular aggregation is responsible for the deterioration of non-blended triazole films phosphorescence.