Decreased Aggregation Phenomena in Polyfluorenes by Introducing Carbazole Copolymer Units

Abstract

To decrease aggregation phenomena and improve the luminescence of the blue-light-emitting polymer polyfluorene, carbazole units were copolymerized to introduce disorder in the polymer backbone. A “kink” linkage was introduced into the polyfluorene chain by forming a 9:1 and 7:3 copolymer with the carbazole group at the 3,6 positions. The disordered polyfluorene was made though a Ni-catalyzed reaction, which resulted in high yield and high molecular weight polymers. The structure and physical properties were confirmed by NMR, SEC, UV absorption, photoluminescence, elemental analysis, and quantum yield measurements. The copolymers exhibited better spectral properties both in solution and in film compared to previously synthesized polyfluorene homopolymers. Annealing studies showed both improved thermal and UV stability of the copolymer over previously reported homopolymers. Cyclic voltammetry studies showed a slightly lower highest occupied molecular orbital (HOMO) than the homopolymer.

Recent Advances in Stimuli‐Responsive Photofunctional Materials Based on Accommodation of Chromophore into Layered Double Hydroxide Nanogallery

“…As well, from a perspective of luminescent efficiency, the aggregates of luminescent molecules are usually readily formed in the solid state, which can lead to an emission shift, line broadening, and even luminescence quenching. Moreover, the thermal/chemical stability and service lifetime of organic materials are generally low for optoelectronic device application [8]. Therefore, how to further enhance the optical performance and stability also became major goals.…”

RAFT “grafting-through” approach to surface-anchored polymers: Electrodeposition of an electroactive methacrylate monomer

“…In our group, carbazolecontaining polymers and dendrimers have been synthesized and studied [24][25][26][27][28] because of their potential applications on electroluminescent devices [29][30][31], photorefractive materials [32,33], electrochromic materials [34,35], and memory devices [36]. In all the above applications, the main use of carbazole-derivatized polymers for electro-optical function involves efficient hole transport, good solution processing properties, and high chemical stability [37][38][39][40].…”

“…In all the above applications, the main use of carbazole-derivatized polymers for electro-optical function involves efficient hole transport, good solution processing properties, and high chemical stability [37][38][39][40]. Using the precursor polymer approach, polymers with electroactive side-chain functional groups can form conjugated polymer networks (CPNs) on the electrode surface upon chemical or electrochemical oxidation processes [24][25][26][27][28]37]. The CPN formation [41,42] has also been applied to dendrimeric precursors forming shape-persistent conjugated nano-objects and electrooptically active films [43,44].…”

(9,9-Dialkylfluorene-co-fluorenone) copolymers containing low fluorenone fractions as model systems for degradation-induced changes in polyfluorene-type semiconducting materials

“…with an ongoing aggregate or excimer formation is at the very least questionable [6,11,12]. Hereby, the strong influence of di-and triarylamine-type dopants and building blocks (in copolymers) on the intensity of the low energy emission bands in PFs [13,14] may be related to PL (and EL) quenching processes. As demonstrated previously, also the decoration of the PF backbone with bulky arylene-type dendronic side-chains leads to an increased chemical stability and reduced interchain energy transfer [15].…”