An Organic Molecule with Asymmetric Structure Exhibiting Aggregation‐Induced Emission, Delayed Fluorescence, and Mechanoluminescence

Abstract

Compounds displaying delayed fluorescence (DF), from severe concentration quenching, have limited applications as nondoped organic light-emitting diodes and material sciences. As a nondoped fluorescent emitter, aggregation-induced emission (AIE) materials show high emission efficiency in their aggregated states. Reported herein is an AIE-active, DF compound in which the molecular interaction is modulated, thereby promoting triplet harvesting in the solid state with a high photoluminescence quantum yield of 93.3%, which is the highest quantum yield, to the best of our knowledge, for long-lifetime emitters. Simultaneously, the compound with asymmetric molecular structure exhibited strong mechanoluminescence (ML) without pretreatment in the solid state, thus exploiting a design and synthetic strategy to integrate the features of DF, AIE, and ML into one compound.

Molecular Conformation‐Dependent Mechanoluminescence: Same Mechanical Stimulus but Different Emissive Color over Time

“…[12] However, much different ML behaviors appeared if the mechanical stimulus continued. [12] However, much different ML behaviors appeared if the mechanical stimulus continued.…”

Renaissance of Organic Triboluminescent Materials

“…[37] As the luminescence of AIE-active materials is not quenched, but is enhanced in the solid state,i ti se xpected that many AIE- [38] Thed issymmetrical structure of the molecules facilitates its crystallization in anoncentrosymmetric space group,which is essential to achieve TL properties.I n2 015, Xu et al also found that molecules such as 5-[4-(1,2,2-triphenylvinyl)phenyl]thiophene-2-carbaldehyde (P4TA)s how remarkable TL properties (Figure 9). [37] As the luminescence of AIE-active materials is not quenched, but is enhanced in the solid state,i ti se xpected that many AIE- [38] Thed issymmetrical structure of the molecules facilitates its crystallization in anoncentrosymmetric space group,which is essential to achieve TL properties.I n2 015, Xu et al also found that molecules such as 5-[4-(1,2,2-triphenylvinyl)phenyl]thiophene-2-carbaldehyde (P4TA)s how remarkable TL properties (Figure 9).…”

A novel coumarin-based red fluorogen with AIE, self-assembly, and TADF properties

“…The results suggest that the origin of the PL emission enhancement of CDPA is TADF, which presented different temperature dependence degrees. [47] Fig In order to clarify why the DF emission of CDPA were observed, quantum chemical calculations for S 0 states were carried out using density functional theory (DFT) at the B3LYP/6-31G(d) level. Fig.12 shows the optimized structure and the HOMO and LUMO of CDPA.…”

“…[12][13][14] Such abnormal fluorescent behaviour is ascribed to the restriction of internal rotations (RIR) as well as aggregation inducedplanarization and formation of J-aggregates in some cases. [15][16][17][18] AIE materials have received increasing attentions in recent years and successfully applied for sensing and bioimaging [19][20][21][22][23][24][25], OLEDs [26] and optical waveguides. [27] The results reveal that these AIE luminogens are not only strongly emissive in the solid states, but also responsive to external stimuli such as grinding and chemical vapour.…”