<scp>Synthesis</scp> and Electrochromic Characterization of Multifunctional, Novel Carbazole and Fluorene Conducting Polymers Containing Azobenzene and Coumarin Chromophore Units

ABSTRACT Herein, synthesis, polymerization, electrochemical, and electrochromic properties of four novel, multifunctional thiophene and carbazole/fluorene comprising π‐conjugated conducting polymers were reported. Polymers were functionalized with strong chromophore units such as azobenzene and coumarin to observe the effect of different functional units (carbazole and fluorene) and chromophore units (azobenzene and coumarin) on electrochemical and electrochromic behaviors. Homopolymers were synthesized chemically, and electronic, electrochromic, and optical properties of homopolymers were investigated by cyclic voltammetry, spectroelectrochemical, and kinetic studies. Some crucial parameters such as oxidation potentials, HOMO/LUMO energy levels, band gaps ( E g op ), optical contrasts (T%), and switching times were calculated from these analyses to investigate the applicability of these polymers in different fields, namely, electrochromic devices, supercapacitors, and organic solar cells. Carbazole comprising polymers P1 and P2 exhibited similar optical and electrochromic behaviors; optical band gap ( E g op ) values were calculated as 1.67 eV for P1 and 1.89 eV for P2. Both P1 and P2 exhibited different tones of red colors in the neutral states with different tones of gray colors in the oxidized states and with different intermediate colors. Similarly, fluorene‐bearing P3 and P4 also exhibited similar optical and electrochromic behaviors. E g op values were calculated as 2.24 and 2.18 eV for P3 and P4, respectively. Both P3 and P4 exhibited yellow colors in the neutral states with different tones of gray colors in the oxidized states and with different intermediate colors. Finally, the long‐term stability of P2 was also investigated at 500 nm, and the studies showed that P2 retains its electrochromic behavior without a certain loss, which makes it a good candidate for electrochromic applications.