The impact of [1,2,5]chalcogenazolo[3,4-f]-benzo[1,2,3]triazole structure on the optoelectronic properties of conjugated polymers |
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Authors: | Ecem Aydan Alkan Seza Goker Hatice Sarigul Erol Yıldırım Yasemin Arslan Udum Levent Toppare |
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Affiliation: | 1. Department of Chemistry, Middle East Technical University, Ankara, Turkey;2. Department of Chemistry, Middle East Technical University, Ankara, Turkey Solid Propellant Department, Roketsan Missiles Inc., Ankara, Turkey;3. Department of Chemistry, Middle East Technical University, Ankara, Turkey Department of Polymer Science and Technology, Middle East Technical University, Ankara, Turkey;4. Technical Sciences Vocational School, Gazi University, Ankara, Turkey |
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Abstract: | Two novel conjugated near-infrared (NIR) absorbing donor–acceptor type copolymers comprising benzodithiophene as the donor and [1,2,5]chalcogenazolo[3,4-f]-benzo[1,2,3]triazole derivatives as the acceptors, spaced with thiophene as the π-bridge, were designed and synthesized via Stille polycondensation reaction. The effect of acceptor strength on optoelectronic properties was targeted and investigated. Branched alkyl chains (the extended 2-octyl-1-dodecyl alkyl chain; C8C12) were introduced to 5H-[1,2,3]triazolo[4′,5′:4,5]benzo[1,2-c][1,2,5]thiadiazole and 5H-[1,2,3]triazolo[4′,5′:4,5]benzo[1,2-c][1,2,5]selenadiazole for enhanced solubility of polymers which ease the processability hence device constructions. The strongly electron-withdrawing units lead to a substantial change in the absorption properties via promotion of the intramolecular charge transfer band alongside the π–π* transition. The resultant soluble polymers were characterized via cyclic voltammetry to determine highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels as −5.00 and −3.92 eV for PSBT and −4.86 and −4.04 eV for PSeBT, respectively. Electronic band gaps of the copolymers were calculated as 1.08 eV for PSBT and 0.82 eV for PSeBT, respectively. NIR absorbing copolymers were used to construct electrochromic devices. |
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Keywords: | benzo[1,2-b:4,5-b′]dithiophene benzotriazole chalcogen conjugated polymers electrochromism |
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