The electronic structure and reflectivity of PEDOT:PSS from density functional theory

Abstract

The geometric and electronic structure of condensed phase organic conducting polymer PEDOT:PSS blends has been investigated by periodic density functional theory (DFT) calculations with a generalized-gradient approximation (GGA) functional, and a plane wave basis set. The influence of the degree of doping of the PEDOT polymer on structural and optical parameters such as the reflectivity, absorbance, conductivity, dielectric function, refractive index and the energy-loss function is studied. A flip from the benzoid to the quinoid structure is observed in the calculations when the neutral PEDOT is doped by negatively charged PSS. Also the optical properties are affected by the doping. In particular, the reflectivity was found to be very sensitive to the degree of doping, where higher doping implies higher reflectivity. The reflectivity is highly anisotropic, with the dominant contribution stemming from the direction parallel to the PEDOT polymer chain.

Ultrafast charge and discharge biscrolled yarn supercapacitors for textiles and microdevices

“…The MWNT volume (V c ) was calculated by dividing MWNT mass by the density of MWNT bundles (B1.67 g cm À 3 ). The PEDOT volume (V p ) was calculated by dividing the PEDOT mass by PEDOT density, using 1.47 g cm À 3 for the density of PEDOT 36 . Sheet stack mass was measured before and after PEDOT coating using a microbalance to obtain the wt% of PEDOT in the yarn.…”

Optical Spectra of p-Doped PEDOT Nanoaggregates Provide Insight into the Material Disorder

“…As compared to neutral oligomers, the ground state of p-doped oligomers has a quinoid form [19,20], which results in a delocalization of the charge carriers over several monomers. During deposition, typically via spincoating, the PEDOT oligomers rearrange, resulting in formation of supramolecular aggregates with a characteristic π − π-stacking intermolecular distance of 0.34 nm.[21] Figure 1(b-c) shows two widely discussed packing motifs -parallel stacks [14] and head-to-tail chains [15]. Both motifs would exhibit similar π − π-stacking distances in x-ray scattering measurements.…”

“…Details of TDDFT calculations are provided in the Supplementary Information. As compared to previous theoretical studies of PEDOT optical spectra [14,15,36], here we focus on the formation of small disordered clusters that include random displacements rather than a periodic crystalline orientation or arrangement of PEDOT oligomers on a polymer backbone. To our knowledge, the role of structural disorder in the optical properties of PEDOT-based materials has not yet been explored in detail.…”

“…[21] Figure 1(b-c) shows two widely discussed packing motifs -parallel stacks [14] and head-to-tail chains [15]. Both motifs would exhibit similar π − π-stacking distances in x-ray scattering measurements.…”

“…Second, in a pair or stack of PEDOT oligomers, each individual oligomer can be displaced relative to its neighbor along the Figure 1: PEDOT oligomer geometries (a) Optimized structure of a single PEDOT oligomer (some hydrogens not visible) (b-c). Two packing models considered in the study: (b) a stack of parallel oligomers [14] and (c) a double-layer head-to-tail packing [15]. The blue ellipsoid and ribbon represent counterions equilibrating the PEDOT charges.…”