Synthesis and characterization of semiconductor polymer doped with FeCl$_{3}$, I$_{2}$

The conductive polymer-based applications combine low cost, simple manufacturing procedure, flexibility and other properties. However, the low viscosity and solubility of these polymers make it difficult to produce layers by using industrial techniques. Among the most commonly used conjugated conductive organic polymers we can mention polyacetylene, polythiophene, polypyrrole, polyaniline, etc. In order to test them in further applications, new copolymers of thiophene and $p$-methoxybenzaldehyde were synthesized. The copolymers obtained will be characterized by several techniques (NMR, UV, CV, ATG, and electrical characterization). The study of the optical properties after doping is performed according to oxidation-reduction reactions by FeCl$_{3}$, I$_{2}$, in order to apprehend the redox behavior of this copolymer. The calculated value of energy gap Eg$^{\operatorname{CV}}$ of the studied polymers shows a decrease with the oxidation agent doping according to their oxidation potential, from 2.48 eV for the no doped copolymer passing by 2.22 eV for the copolymer doped with I$_{2}$ and up to 1.5 eV for the copolymer doped with FeCl$_{3}$. The decrease of the energy gap with the doping (FeCl$_{3}$ and I$_{2}$) corresponds to the increase of the conductivity with doping from 2.85 $\cdot$ 10$^{-5}$ S $\cdot$ m$^{-1}$ for no doped polymer to 7.86 $\cdot$ 10$^{-5}$ S $\cdot$ m$^{-1}$ for copolymer doped with I$_{2}$ and 1.55 $\cdot$ 10$^{-4}$ S $\cdot$ m$^{-1}$ for copolymer doped with FeCl$_{3}$.