Utilizing d–pπ Bonds for Ultralong Organic Phosphorescence

Abstract

Developing pure organic materials with ultralong lifetimes is attractive but challenging. Here we report a concise chemical approach to regulate the electronic configuration for phosphorescence enhancement. After the introduction of d–pπ bonds into a phenothiazine model system, a phosphorescence lifetime enhancement of up to 19 times was observed for DOPPMO, compared to the reference PPMO. A record phosphorescence lifetime of up to 876 ms was obtained in phosphorescent phenothiazine. Theoretical calculations and single‐crystal analysis reveal that the d–pπ bond not only reduces the (n, π*) proportion of the T1 state, but also endows the rigid molecular environment with multiple intermolecular interactions, thus enabling long‐lived phosphorescence. This finding makes a valuable contribution to the prolongation of phosphorescence lifetimes and the extension of the scope of phosphorescent materials.

Manipulating the Ultralong Organic Phosphorescence of Small Molecular Crystals

“…It was found that the phosphors 8 and 9 showed a remarkable increase in the phosphorescence lifetime compared with molecules 6 and 7 . From the theoretical calculations and single‐crystal analysis, they found that the d–pπ bonds not only reduced the (n, π*) ratio of the T 1 state and achieved the near pure (π, π*) configuration of the T 1 state, but also enabled the rigid molecular environment with multiple intermolecular interactions, thus achieving long‐lived phosphorescence …”

Manipulating the Stacking of Triplet Chromophores in the Crystal Form for Ultralong Organic Phosphorescence

“…Broadly defined, molecular packing involves the stacking between various groups. Some groups, such as carbazole, phenothiazine,– etc., favor triplet excited states and could be regarded as triplet chromophores for manipulating phosphorescence generation, whereas others can be seen as functional groups that may be used to manipulate molecular packing by tuning intermolecular interactions (Figure a). It is important to identify which group, when stacked in crystal form, is essential for UOP generation.…”

Crystal‐State Photochromism and Dual‐Mode Mechanochromism of an Organic Molecule with Fluorescence, Room‐Temperature Phosphorescence, and Delayed Fluorescence

“…[2] However,R TP from metal-free organic materials is rare because of the spin-forbidden nature of phosphorescence processes,a nd the easily quenched excited triplet state by thermal molecular motions and oxygen. [4] However,t he development of organic materials with efficient RTPp roperties still remains at the preliminary stage. [4] However,t he development of organic materials with efficient RTPp roperties still remains at the preliminary stage.…”