In this paper, the optical properties and optoelectronic parameters of two newly synthesized polymers forming a donor : acceptor (D : A) binary system are investigated, followed by their subsequent doping with Sudan dye to obtain a ternary system. The donor polymer is P(TER-CO-TRI), while the acceptor is poly(5-hydroxy-L-Tryptophane). A cost-effective solution-processing was carried out to obtain different binary and ternary composites with concentration of 0.5 mg/ml. Optical absorption spectroscopy was used to measure the optical response and optoelectronic parameters, while FTIR and cyclic voltammetry were used to assess the structure and molecular energy levels of the polymers. The results revealed that the non-dispersive refractive index and energy gap of binary D : A was decreased from 1.56 to 1.52 eV and from 2.84 to 2.10 eV, respectively, when it was doped with Sudan dye. It was concluded that with the help of doping process, different values of energy band gap, refractive index, dielectric constant, and optical conductivity are achieved. This tuning achievement of the optoelectronic parameters is crucial in determining the possible applications of these materials in the organic electronics, photodiodes and photovoltaic devices.

In this work, the optical properties and optoelectronics parameters of binary and ternary composite films made of two electron acceptors, poly(L-Tryptophane) and poly(5-hydroxy-L-Tryptophane), with an electron donor, P(TER-CO-TRI), doped with Sudan dyes, are comprehensively investigated. The films with different volumetric ratios of the components were deposited onto the glass substrates using spin coating technique. Results showed that with the help of dye doping into the binary systems of poly(L-Tryptophane):P(TRI-co-TER) (1:2) and poly(5-hydroxy-L-Tryptophane):P(TRI-co-TER)(1:2), the refractive index was increased from 2.01 to 2.32. The nature of the electronic transition in the studied films was found to be a direct allowed transition, which was derived from Tauc’s equation. The combination of Cyclic voltammetry (CV) technique and absorption spectroscopy was used to determine the molecular energy levels, HOMO and LUMO of the polymer samples. It was seen that the mixture of poly(L-Tryptophane):P(TRI-co-TER):Sudan dye (1:2:2) has led to increase the energy gap to 2.95 eV and the real optical conductivity ( ) to about 433.11 S.cm-1. According to the findings, the investigated polymers can have a great potential for semitransparent organic solar cells.