No abstract

Manipulation of the emission properties of pure organic room-temperature phosphors through molecular design is attractive but challenging. Tremendous efforts have been made to modulate their aggregation behaviors to suppress nonradiative decay in order to achieve efficient light emission and long lifetimes. However, success has been limited. To attain such a goal, here we present a rational design principle based on intrinsic molecular-structure engineering. Comprehensive investigations on the molecular orbitals revealed that an excited state with hybrid (n,p*) and (p,p*) configurations in appreciable proportion is desired. Tailoring the aromatic subunits in arylphenones can effectively tune the energy level and the orbital feature of the triplet exciton. Our experimental data reveal that a series of full-color pure organic phosphors with a balanced lifetime (up to 0.23 s) and efficiency (up to 36.0%) can be realized under ambient conditions, demonstrating the validity of our instructive design principle.

The development of single molecule white light emitters is extremely challenging for pure phosphorescent metal-free system at room temperature. Here we report a single pure organic phosphor, namely 4-chlorobenzoyldibenzothiophene, emitting white room temperature phosphorescence with Commission Internationale de l’Éclair-age coordinates of (0.33, 0.35). Experimental and theoretical investigations reveal that the white light emission is emerged from dual phosphorescence, which emit from the first and second excited triplet states. We also demonstrate the validity of the strategy to achieve metal-free pure phosphorescent single molecule white light emitters by intrasystem mixing dual room temperature phosphorescence arising from the low- and high-lying triplet states.