Synthesis and structure–property relationship of carbazole‐alt‐benzothiadiazole copolymers

Abstract

A series of four π‐conjugated carbazole‐alt‐benzothiadiazole copolymers (PCBT) were prepared by Suzuki cross‐coupling reaction between synthesized dibromocarbazoles as electron‐rich subunits and 4,7‐bis(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)−2,1,3‐benzothiadiazole as electron‐deficient subunits. The subunits were directly linked through 2,7‐ or 3,6‐ positions of the carbazole. In addition, the carbazole monomers have been N‐substituted by a branched or a linear side‐chain. The chemical structure of the copolymers and their precursors was confirmed by NMR and IR spectroscopies, and their molar masses were estimated by SEC. Thermal analysis under N2 atmosphere showed no weight loss below 329°C, and no glass transition was observed in between 0 and 250°C. The band gaps of all PCBTs evaluated by optical spectroscopies and by cyclic voltammetry analysis were consistent with expectations and ranged between 2.2 and 2.3 eV. Finally, 2,7 and 3,6 linkages were shown to influence optical properties of PCBTs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2059–2068

Photophysics, electronic structure and solar cell performance of a donor-acceptor poly(N-dodecyl-2,7-carbazole-alt-benzothiadiazole) copolymer

“…low leakage current and distinct turn-on voltage of ~0.8 V). XRD spectra of CBZ-BT and its blends with PC70BM showed no diffraction peaks (not shown), even after annealing up to 150° C, indicating that the copolymer is amorphous, as also verified previously by differential scanning calorimetry analyses [65]. Finally, the surface morphology of the CBZ-BT:PC70BM (1:2 wt.% ratio) blend films was investigated by atomic force microscopy (AFM) in order to unveil its possible influence on the PSC performance.…”

“…The investigated poly(N-dodecyl-2,7carbazole-alt-benzothiadiazole) (CBZ-BT) copolymer synthesized via Suzuki coupling polymerization was optically and electronically characterized both in solution and thin films [65]. Its chemical structure is shown in Fig.…”

“…Herein, we report in detail on the optoelectronic properties of a solution-processed polycarbazole-benzothiadiazole (CBZ-BT) based copolymer recently synthesized and computationally investigated by our group [65,66], its steady state and ultrafast photophysics upon blending with a fullerene PC70BM acceptor and its utilization as a donor in simple architecture polymer solar cells. A set of optical spectroscopy techniques such as stationary absorption and fluorescence as well as fs to ns time resolved and upconversion fluorescence spectroscopy have been used including polarization sensitive measurements.…”

The dielectric and electrical proprieties of Ethylcarbazole family based copolymer

“…Furthermore, its nitrogen group can be easily substituted to provide solubility to the polymer 11 . The carbazole based compounds exhibit high thermal and photochemical stability and some unique electrical properties 12 .…”

Conjugated polymers with carbazole, fluorene, and ethylene dioxythiophene in the main chain and a pendant cyano group: Synthesis, photophysical, and electrochemical studies

“…The carbazole moiety, apart from extending the conjugation, imparts excellent hole transporting property, high triplet energy, amorphous nature, and can be easily functionalized by reaction at the nitrogen atom. Moreover, on incorporation of carbazole, thermal and photochemical stability, and durability of the polymers were found to be significantly improved . The presence of bulky cyano group in the CPs hinders π‐π stacking and maintains coplanarity, which are essential factors for the formation of J‐type aggregation leading to aggregation enhanced emission (AEE) …”