AIE-Active Fluorene Derivatives for Solution-Processable Nondoped Blue Organic Light-Emitting Devices (OLEDs)

Abstract

A series of fluorene derivatives end-capped with diphenylamino and oxadiazolyl were synthesized, and their photophysical and electrochemical properties are reported. Aggregation-induced emission (AIE) effects were observed for the materials, and bipolar characteristics of the molecules are favored with measurement of carrier mobility and calculation of molecular orbitals using density functional theory (DFT). Using the fluorene derivatives as emitting-layer, nondoped organic light-emitting devices (OLEDs) have been fabricated by spin-coating in the configuration ITO/PEDOT:PSS(35 nm)/PVK(15 nm)/PhN-OF(n)-Oxa(80 nm)/SPPO13(30 nm)/Ca(8 nm)/Al(100 nm) (n = 2-4). The best device with PhN-OF(2)-Oxa exhibits a maximum luminance of 14 747 cd/m(2), a maximum current efficiency of 4.61 cd/A, and an external quantum efficiency (EQE) of 3.09% in the blue region. Investigation of the correlation between structures and properties indicates that there is no intramolecular charge transfer (ICT) increase in these molecules with the increase of conjugation length. The device using material of the shortest conjugation length as emitting-layer gives the best electroluminescent (EL) performances in this series of oligofluorenes.

Self‐Assembling Azaindole Organogel for Organic Light‐Emitting Devices (OLEDs)

“…Among the diverse strategies developed to mitigate the ACQ effect, the utilization of small molecules experiencing the so called aggregation‐induced emission (AIE) phenomenon proposed by Tang and co‐workers has been identified as an emerging and successful approach. This phenomenon is observed for some molecules that are nonemissive or weakly fluorescent molecules in dilute solutions and upon aggregation do not achieve a sandwich packing.…”

“…Hence on one hand there is no reduction of the fluorescence rate constant and efficiency, related to the exciton splitting, while on the other hand the aggregation leads to a more rigid environment blocking the nonradiative deactivation channels as large amplitude vibrations or rotations occurring in solution . Thus, although this type of molecules has been implemented as active materials in solution‐processable blue OLEDs, there are still important limitations for the further development of AIE‐based OLEDs as the poor thermal properties and low electron/hole carrier mobility . An original approach to surpass these weaknesses is the employment of self‐assembled organogelators with AIE properties since the intermolecular interactions formed in the 3D network of the organogel may assist to increase the transference of charge in the emissive material but maintaining the AIE properties.…”

Threonine-Based Stimuli-Responsive Nanoparticles with Aggregation-Induced Emission-Type Fixed Cores for Detection of Amines in Aqueous Solutions

“…In contrast, various AIE molecules with similar molecular designs and properties have recently been developed and employed as luminogens, otherwise known as AIEgens, that exhibit emission in the solid state. In addition to the more well-known AIEgens, such as tetraphenylethylene derivatives, fluorene derivatives have been frequently investigated as AIEgens [ 64 , 65 , 66 ]. In the present system, NP(Fl) with the diphenyl Fl core can be recognized as AIE-active NPs, showing strong emission in the aggregated and the solution state, owing to the restricted rotation between the phenyl-Fl units in the cross-linked core.…”

H2PO4–- and Solvent-Induced Polymorphism of an Amide-Functionalized [Pt(N^C^N)Cl] Complex

“…This solid-state polymorphism makes it potentially useful in light-emitting devices. 56,57 ■ EXPERIMENTAL SECTION Synthesis. NMR spectra were recorded in the designated solvent on Bruker Avance 400 MHz spectrometer.…”