High contrast temperature-responsive luminescence materials from purely organic molecule with persistent room-temperature phosphorescence

Organic materials with temperature-responsive luminescence (TRL) generally exhibit step-change of luminescent intensity during temperature variation. The persistent room-temperature phosphorescence (pRTP) materials have significant advantages in long-lived triplet excitons, which are promising new type of TRL materials. Here, a D-A type benzophenone derivative, namely BrBDBF, has been designed and synthesized. Interestingly, two crystals (BrBDBF-Y and BrBDBF-W) with different pRTP properties are found for BrBDBF. In addition, the bright crystal BrBDBF-Y presented a temperature-induced tunable emission color-switching from bluish-green to yellow. While the crystal BrBDBF-W with very weak emission exhibited high contrast "turn-on" luminescence which increased about 40 times as the temperature dropping. These results demonstrate that BrBDBF is a new type of TRL material and provides opportunities for the advanced application of organic pRTP materials.