Quantum Molecular Dynamical Calculations of PEDOT 12-Oligomer and its Selenium and Tellurium Derivatives

Amina Mirsakiyeva,Xavier Crispin,Håkan W Hugosson,Anna Delin

doi:10.1007/s11664-016-5161-6

Abstract

We present simulation results, computed with the Car–Parrinello molecular dynamics method, at zero and ambient temperature (300 K) for poly(3,4-ethylenedioxythiophene) [PEDOT] and its selenium and tellurium derivatives PEDOS and PEDOTe, represented as 12-oligomer chains. In particular, we focus on structural parameters such as the dihedral rotation angle distribution, as well as how the charge distribution is affected by temperature. We find that for PEDOT, the dihedral angle distribution shows two distinct local maxima whereas for PEDOS and PEDOTe, the distributions only have one clear maximum. The twisting stiffness at ambient temperature appears to be larger the lighter the heteroatom (S, Se, Te) is, in contrast to the case at 0 K. As regards point charge distributions, they suggest that aromaticity increases with temperature, and also that aromaticity becomes more pronounced the lighter the heteroatom is, both at 0 K and ambient temperature. Our results agree well with previous results, where available. The bond lengths are consistent with substantial aromatic character both at 0 K and at ambient temperature. Our calculations also reproduce the expected trend of diminishing gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital with increasing atomic number of the heteroatom.

Highlights

Poly(3,4-ethylenedioxythiophene) (PEDOT) is a conducting polymer with wide technological use in, e.g., organic transistors, photovoltaic devices, displays, and biosensors
We present a theoretical investigation, using computational methods based on density functional theory (DFT), of the geometrical structure and charge distribution at ambient temperature of neutral PEDOT and its derivatives PEDOS and PEDOTe, i.e., derivatives where the sulfur atoms have been replaced by selenium and tellurium, respectively
The difference between long and short bonds is smallest in PEDOT, and largest in PEDOTe

Summary

Introduction

Poly(3,4-ethylenedioxythiophene) (PEDOT) is a conducting polymer with wide technological use in, e.g., organic transistors, photovoltaic devices, displays, and biosensors. We present a theoretical investigation, using computational methods based on density functional theory (DFT), of the geometrical structure and charge distribution at ambient temperature of neutral PEDOT and its derivatives PEDOS and PEDOTe, i.e., derivatives where the sulfur atoms have been replaced by selenium and tellurium, respectively.

Results

Conclusion