Effect of pyrazine in PEDOT:PSS thin films: Structural, optical, optoelectrical, and electrical analysis

Abstract

The pristine PEDOT:PSS and different weight amounts of pyrazine in PEDOT:PSS thin films were prepared using the doctor-blading technique on a borosilicate glass substrate. The structural, optical, and electrical properties of the effect of pyrazine in PEDOT:PSS thin films were presented for the first time of this admixed solution. More accuracy in the surface of thin films was observed by atomic force microscopy (AFM) which revealed the granular deposits on the film surfaces. Some hill shapes and the distribution of agglomerated grains were also observed on the thin films. The PEDOT:PSS with pyrazine has a preferred orientation to be an orthorhombic crystal structure. The crystallite sizes were reduced from 230.40 nm to 101.81 nm for 30–60 mg pyrazine in the PEDOT:PSS. The energy band gap (Eg) value of pristine PEDOT:PSS is of 3.50 eV with Urbach energy (EU) of 336.10 meV. The alteration Eg values from 3.52 to 3.67 eV was obtained with the estimated EU values in the range of 283.16–324.62 meV depends on various amounts of pyrazine. The linear optical parameters, i.e., the refractive index, optical electronegativity, real/imaginary dielectric constants, extinction coefficient, and optical conductivity were investigated and explained by the changes in the formation, nucleation, growth of clusters, and particle arrangement. As the spectrum increased, the highest χ(1), χ(3), and n2 values were obtained for the 80 mg pyrazine in PEDOT:PSS of 0.110, 2.562 × 10−14 esu, and 6.219 × 10−13 esu, respectively. The electrical conductivity was clearly increased for pyrazine exceeding 40 mg from 1.85 × 102 to 3.84 × 102 S/cm and the figure of merit was in the range of 4.34 × 10−2 to 4.68 × 10−2 Ω−1. Thus, the novelty of this work can show that pyrazine in the range of 40 mg–80 mg is the optimum condition to synthesize non-linear optical (NLO) materials, organic light-emitting diodes (OLEDs), and organic light-emitting transistors (OLETs).