Improving the Performance of Polythiophene-based Electronic devices by Controlling the Band Gap in the Presence of Graphene

TL;DR

This study uses advanced computational methods to analyze how adsorbing polythiophene on graphene modifies its electronic properties, particularly reducing its band gap through interfacial effects.

Contribution

It provides new insights into how substrate interactions influence the electronic structure of polythiophene, especially the band gap modulation via orbital hybridization and polarization effects.

Findings

Graphene adsorption causes a -0.19 eV work function shift.

Polythiophene's band gap is significantly reduced due to interfacial polarization.

Orbital hybridization modifies energy level lineshapes without changing the LDA band gap.

Abstract

Density functional theory (DFT) and many body perturbation theory at the G$_0$W$_0$ level are employed to study the electronic properties of polythiophene (PT) adsorbed on graphene surface. Analysis of charge density difference shows the substrate-adsorbate interaction leading to a strong physisorption and interfacial electric dipole moment formation. The electrostatic potential displays a -0.19 eV shift in the graphene work function from its initial value of 4.53 eV, as the result of the interaction. The LDA band gap of the polymer does not show any change, however the energy level lineshapes are modified by the orbital hybridization. The interfacial polarization effects on the band gap and levels alignment are investigated within G$_0$W$_0$ level and shows notable reduction of PT band gap compared to that of the isolated chain.