Polythiophenes and optical changes

Thiophene-based polymers exhibit high conductivities in their doped states, offering good processability and interesting optical and electronic properties. Due to their exhibition of diverse color variations and their high contrast ratios, functionalized polythiophenes have become popular as electrochromic materials. 

Polythiophenes with P-alkyl substituents including more than three carbon atoms are commonly soluble in organic solvents. Recently, electrochromic polymers such as poly(thiophene-3-acetic acid) and its copolymer with polythiophene were prepared. The electrochromic properties of these materials were studied by observing a color change from red to black during the potential sweep with a stability for 264 cycles, establishing a high electrochromic efficiency of up to 242 cm C at 750 nm [65], 

Sonmez et al. suggested that at least two chromophores are required that absorb at two different wavelengths to obtain a green-colored conducting polymer. They supported this claim by designing the monomer 

3- di(thien-3-yl)-5,7-di(thien-2-yl)thieno[3,4-fc]pyrazine, which resulted in a green-colored polymer in its neutral state [67], They prepared a soluble, neutral green conducting polymer of dioctyl-substituted 

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