Investigating unusual photoluminescence from the excited state in a DCM derivative and its application in lighting devices

Abstract

We report a comprehensive investigation of the anti-Kasha phenomenon in 2-(2,6-bis((E)-2-(pyren-1-yl)vinyl)-4H-pyran-4-ylidene)malononitrile (DCM-Py). This was a promising dual-emissive fluorophore exhibiting simultaneous blue and orange emission in solution with quantum yield up to 30%. Through state-of-the-art experimental characterization and quantum chemical modeling, we revealed genuine anti-Kasha behavior by systematically excluding potential artifacts. The unique photophysical properties of DCM-Py were harnessed in functional organic light-emitting diode (OLED) prototypes, demonstrating dual bands in the electroluminescence spectrum and yellow emission in a device. The electrically generated exciton in the device had a similar channel to relax to ground state as in solution, indicative of a multi-state exciton relaxation pathway in the emissive layer (DCM-Py), further showcasing an anti-Kasha property.