# Explore the Structural and Electronic Properties at the Organic/Organic Interfaces of Thiophene-Based Supramolecular Architectures

## TL;DR

This paper explores how organic molecules arrange and interact at their interfaces, which is important for improving organic electronics.

## Contribution

The study reveals new structural and electronic behaviors at organic/organic interfaces using low-temperature STM/STS.

## Key findings

- DCV5T-Me2 forms compact islands on Au(111) via hydrogen bonding and electrostatic interactions.
- C60 self-assembles into ordered islands on top of DCV5T-Me2 monolayers, with a 400 mV energy difference in LUMO levels.
- Tip-induced electric fields can control the charging of TCNQ in hybrid nanostructures with DCV5T-Me2.

## Abstract

The structural and electronic properties at organic/organic interfaces determine the functionality of organic electronics. Here, we investigated the structural and electronic properties at interfaces between methyl-substituted dicyanovinyl-quinquethiophenes (DCV5T-Me2) and other electron acceptor molecules, namely fullerene (C60) and tetracyanoquinodimethane (TCNQ), by using low-temperature scanning tunneling microscopy/spectroscopy (STM/STS). Upon adsorption on Au(111), DCV5T-Me2 molecules self-assemble into compact islands at sub-monolayer coverage through hydrogen bonding and electrostatic interactions. A similar bonding configuration dominates in the second layer of a bilayer film, where DCV5T-Me2 possesses higher-lying LUMO (lowest unoccupied molecular orbital) and LUMO+1 in energy due to a decoupling effect. The co-deposition of DCV5T-Me2 and C60 does not result in ordered hybrid assemblies at the sub-monolayer coverage on Au(111). On the other hand, C60 molecules can self-assemble into ordered islands on top of the DCV5T-Me2 monolayer. The dI/dV spectra reveal that the LUMO of decoupled C60 is 400 mV lower in energy than the LUMO of decoupled DCV5T-Me2. This energy difference facilitates electron transfer from DCV5T-Me2 to C60. The co-deposition of DCV5T-Me2 and TCNQ leads to the formation of hybrid nanostructures. A tip-induced electric field can manipulate the charging and discharging of TCNQ by surrounding DCV5T-Me2, manifested as sharp peaks and dips in dI/dV spectra recorded over TCNQ.