Effect of Intermolecular Interaction on the Properties of Benzophenone-based AIDF Materials

Four benzophenone luminescent materials with phenoxazine as donor were synthesized. The effects of different aromatic substituents on the intermolecular interaction and photoelectric properties of the materials were investigated. The coplanar modification of polycyclic aromatic hydrocarbons will result in a large number of strong pi-pi stacking interactions between molecules, while the three-dimensional triptycene group can avoid these interactions. The four compounds had very high thermal stability. Their temperature corresponding to 5% mass loss to the initia mass (T-d,T-5) was above 400 degrees C, the pi-pi stacking between molecules will obviously improve the thermal stability of the materials. Except for the perylene modified compounds, the other three compounds had obvious aggregation-induced delayed fluorescence (AIDF), their calculated energy gap (Delta E-st) values were not exceed 0.01 eV. Their photoluminescence efficiency in PMMA thin films was high. The photoluminescence efficiency in PMMA thin films was between 0.60 and 0.78, and increased first and then decreased with the decrease of intermole-cular force. The electroluminescent performance test showed that the compound modified by triptycene had the best electroluminescent performance. The maximum brightness of the doped device was up to 48480 cd/m(2), and the peak power efficiency (PEmax) and peak external quantum efficiency (EQE(max)) were 54.4 lm/W and 19.0%, respectively. The PEmax and EQE(max) of the undoped device were still as high as 33.5 lm/W and 13.4%, indicating that the concentration quenching phenomenon was well suppressed and it has the potential to be applied to organic electroluminescence.