Density functional theory study of optoelectronic, nonlinear optical, piezoelectric and thermodynamic properties of poly (3,4-ethylenedioxythiophene), poly(3,4-ethylenedioxyselenophene) and their derivatives

In this work, we have investigated the optoelectronic, nonlinear optical, piezoelectric and thermodynamic properties of the poly (3,4-ethylenedioxythiophene)(PEDOT), poly(3,4-ethylenedioxyselenophene)(PEDOS) molecules and their chlorinated and fluorinated derivatives respectively by density functional theory DFT/6-31G (d, p) level of theory. Our results show that all these molecules have good optoelectronic properties, their gap energy (E-gap) is between 2.3 eV and 2.6 eV, which shows that they are semi-conductor materials. The calculated thermodynamic properties highlight that these materials have a high thermal resistivity. The derivatives of PEDOT and PEDOS fluorinated and chlorinated also show that these molecules have good non-linear optical properties because the value of the first molecular hyperpolarizability beta is higher than that of para-nitro aniline (p-NA) which is the reference molecule in non-linear optics. The piezoelectric coefficients of PEDOT (d = 23.51 pC.N-1) and PEDOS (d = 19.67pC.N-1) calculated show that these materials are potential candidates for applications in piezoelectricity.