Aggregation-Induced Emission Enhancement from Disilane-Bridged Donor–Acceptor–Donor Luminogens Based on the Triarylamine Functionality

Abstract

Six novel donor-acceptor-donor organic dyes containing a Si-Si moiety based on triarylamine functionalities as donor units were prepared by Pd-catalyzed arylation of hydrosilanes. Their photophysical, electrochemical, and structural properties were studied in detail. Most of the compounds showed attractive photoluminescence (PL) and electrochemical properties both in solution and in the solid state because of intramolecular charge transfer (ICT), suggesting these compounds could be useful for electroluminescence (EL) applications. The aggregation-induced emission enhancement (AIEE) characteristics of 1 and 3 were examined in mixed water/THF solutions. The fluorescence intensity in THF/water was stronger in the solution with the highest ratio of water because of the suppression of molecular vibration and rotation in the aggregated state. Single-crystal X-ray diffraction of 4 showed that the reduction of intermolecular π-π interaction led to intense emission in the solid state and restricted intramolecular rotation of the donor and acceptor moieties, thereby indicating that the intense emission in the solid state is due to AIEE. An electroluminescence device employing 1 as an emitter exhibited an external quantum efficiency of up to 0.65% with green light emission. The emission comes solely from 1 because the EL spectrum is identical to that of the PL of 1. The observed luminescence was sufficiently bright for application in practical devices. Theoretical calculations and electrochemical measurements were carried out to aid in understanding the optical and electrochemical properties of these molecules.

Rotations in Excited ICT States – Fluorescence and its Microenvironmental Sensitivity

“…[45] The donor units (triarylamines) are not connected with the acceptor unit (thieno [3,4-b]pyrazine) in a conjugated Figure 8. [45] The donor units (triarylamines) are not connected with the acceptor unit (thieno [3,4-b]pyrazine) in a conjugated Figure 8.…”

“…The disilane-bridged donor-acceptor-donor fluorophore 13 was recently investigated by Usuki et al regarding its AIE behavior. [45] The donor units (triarylamines) are not connected with the acceptor unit (thieno [3,4-b]pyrazine) in a conjugated Figure 8. a) Fluorophore 10 combines the TICT fluorescence and the aggregation-induced emission whereby the fluorescence in solid state stems from the excited state intramolecular proton transfer (ESIPT) mechanism.…”

Functionalized pyrene‐based AIEgens: synthesis, photophysical characterization and density functional theory studies

“…To explore AIE of the molecules, photoluminescence spectra were recorded with varying volumes of water percentage in solvent‐poor‐solvent mixture (THF/H2O). Emission intensity of typical organic molecules is generally weaker when treated with solvents of higher dielectric constants, due to the positive solvato‐kinetic effect and various other interactions such as photoinduced electron transfer . Poor solvent mixtures generally enhances fluorescence emission intensity and, in turn, induces restricted intramolecular motion and rotation that leads to enhanced emission from the molecules …”

Fine Tuning of the Electronic Properties of Novel BTPE Using Oligosilanyl Linkages and Their Application in Rapid High-Resolution Visualization of Latent Fingerprints

“…[5][6][7][8][9] Also, the large atomic radius of silicon (Si) and the bulk of the organosilicon linkage aided in improving the solubility and processability effectively, 10 which is beneficial for the practical applications of these materials. [11][12][13][14] Red-, green-, and blue-emissive organic materials are required to realize full-color displays. [15][16][17] Compared with their green and red counterparts, blue organic luminescent materials remain rare yet are in high demand.…”