Ultralong room temperature phosphorescence via the charge transfer-separation-recombination mechanism based on organic small molecule doping strategy

Ultra-long room temperature phosphorescence (URTP) has been increasingly recognized in pure organic luminophor in recent years. Through a simpler molecular design and charge separation-recombination pathway, organic luminophor can achieve even better URTP properties. In this work, we achieved URTP in a system of host-guest doped benzophenone derivatives whose phosphorescence is visible to the naked eye. The differences in the wavelength lifetimes of luminescent emission correspond to different photophysical mechanisms. Through a combination of theoretical calculations and experiments, the host acts as a powerful substrate that restricts the motion of the guest and inhibits the non-radiative transitions of the guest, accompanied by a charge transfer separation-recombination process between the host and the guest, resulting in an URTP phenomenon. Transient absorption results demonstrate the existence of a charge-separated state. The design strategy via charge separation is generic and easy to implement, providing a direction for the future design of doped URTP. [Display omitted] This work developed a novel organic host-guest doping system with excellent URTP properties. The phosphorescence is visible to the naked eye. Since different phosphor wavelengths correspond to different lifetimes, different photophysical processes are illustrated. The charge transfer-separation-recombination process between host and guest is responsible for the realization of URTP.