Intermolecular Hydrogen Bonds Induce Highly Emissive Excimers:  Enhancement of Solid-State Luminescence

Abstract

Aggregation induced emission (AIE) is an amazing property for light emitting materials and has attracted much attention. Here, we report a new kind of AIE materials: fluorenone derivates 2,7-dip-tolyl-fluorenone (DTFO) and 2,7-bis(4-(tert-butylthio)phenyl)-fluorenone (DSFO). Strong light emissions with a large Stokes shift and long lifetime in the solid state originate from the formation of excimers. The crystal structure of DSFO shows that every two molecules are bound together even in the ground state by intermolecular hydrogen bonds and form a particular dimer. When this dimer is excited, it turns into an excimer without arrangement adjustment and likewise without repulsive interactions when the excimer decays back to the dimer; so, the nonradiative decay pathways that exist in common excimers are greatly reduced and thus induce a strongly enhanced luminescence in the solid state. OLED devices employing DTFO as light emitting layers are fabricated and evaluated.

Understanding the Nature of the States Responsible for the Green Emission in Oxidized Poly(9,9‐dialkylfluorene)s: Photophysics and Structural Studies of Linear Dialkylfluorene/Fluorenone Model Compounds

“…Related observations of solid-state emission enhancement in fluorenone-containing compounds have also been made elsewhere. [26,27] Additionally, we have conducted experiments which show that the PLQE of PFO films ordered in the liquid crystalline phase is not drastically impacted when they are heated in air to a point where the PL spectrum becomes almost completely dominated by the g-band: F fresh $45% [28] versus F heat $33% (data not shown).…”

Aggregation-induced emissions of tetraphenylethene derivatives and their utilities as chemical vapor sensors and in organic light-emitting diodes

“…During the process of film formation, the dye molecules aggregate, which often results in a weakening in their emission intensities or even a total quenching of their light emissions. [5][6][7][8] While much effort has been devoted to preventing chromophore aggregation, [9][10][11] it is more desirable and useful to develop new luminophors that can emit efficiently in the aggregation state.…”

“…[12][13][14][15][16] A number of AIE molecules with different structures have subsequently been developed by various research groups. [1][2][3][4][5][6][7][17][18][19][20][21] Many of these AIE dyes, however, are difficult to prepare, involving multistep reactions under stringent conditions. In this work, we synthesized TPE-based luminophors by a onestep reaction in a one-pot procedure and explored the possibility of utilizing the dyes as chemical sensors and OLED components.…”

Starburst Triarylamine Donor–Acceptor–Donor Quadrupolar Derivatives Based on Cyano‐Substituted Diphenylaminestyrylbenzene: Tunable Aggregation‐Induced Emission Colors and Large Two‐Photon Absorption Cross Sections

“…However, such measurements are hampered by the severe light-scattering effects of the dye nano-aggregates on their absorption spectra, which makes the F F determination inaccurate. [26] As an alternative, we estimated the integrals of the PL spectra, which are utilized to make the comparison. As for 3 a, there was almost no PL intensity in the solution for the 0-30 % (v/v) water/THF mixture, but it started to increase swiftly upon the addition of water up to 50 % (v/ v).…”