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The ability to form multi-colored oxidation states upon applied positive potentials, and the narrow band gap of 2,7-substituted carbazole derivatives, had encouraged the development of new carbazole containing polymers with interesting optoelectronic properties. Four conjugated polymers containing substituted carbazole units spaced in the main chain by vinylene and 1,4-phenyleneethynylene segments were synthesized via Stille and Sonogashira coupling reactions. Two different substitution positions of carbazole, such as 2,7- and 3,6-carbazole were used to tune the conjugation length and the charge transfer properties of the resulting polymers. The structures of the obtained polymers were characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy while the electronic and optical properties were investigated as function of carbazole substitution positions or spacer nature by ultraviolet-visible spectroscopy and cyclic voltammetry. The redox behaviour of polymers as films deposited on working electrode was investigated using cyclic voltammetry technique, and the lowest unoccupied molecular orbital and highest unoccupied molecular orbital energy levels values were also determined. Spectroelectrochemical measurements suggested the existence of polaronic and bipolaronic structures of polymers backbones accompanied by multi-electrochromic behavior.

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Three novel soluble poly(arylene vinylene)s containing indolo[3,2-b]carbazole moiety inserted in the polymer chain at 2,8-, 3,9-and 6,12-positions were synthesized and used to study the influence of the linking topology on the optical and electronic properties. The new polymers were obtained through a palladium-catalysed cross-coupling Stille reaction between bis-bromine[3,2-b]indolocarbazoles and trans-1,2-bis(tributylstannyl)ethane in toluene.Polymers were soluble in chlorinated, aromatic and aprotic polar solvents. The structures of polymers were investigated using Fourier transform infrared, 1 H NMR and 13 C NMR spectroscopies. The number-average molecular weights determined using gel permeation chromatography are in the range (6.3-9.4) × 10 3 g mol −1 while thermogravimetric analysis showed the polymers to possess high thermal stability. UV-visible and emission spectroscopy evidenced a bathochromic shift of max for indolocarbazole linking topology in the polymer backbone, in the order: 6,12 < 2,8 < 3,9. Electrochemical properties were investigated by cyclic voltammetry using thin films cast on platinum disc working electrodes and highest occupied and lowest unoccupied molecular orbital energy levels were determined.