# Engineering Interfacial Donor–Acceptor Molecular Cocrystals

## TL;DR

This paper explores how Y6 molecules self-assemble at interfaces and form cocrystals with donor molecules, which could improve organic solar cells.

## Contribution

The study reveals the formation of donor–acceptor interfacial cocrystals through coadsorption on graphite surfaces.

## Key findings

- Y6 self-assembles at the solid–liquid interface when observed with scanning tunneling microscopy.
- Coadsorption with donor molecules creates ordered interfacial cocrystals with tailored structures.
- The findings could help design better interfacial nanostructures for organic electronics.

## Abstract

Y6 is a high-performance non-fullerene acceptor widely
used in
organic solar cells. The assembly behavior of Y6 at interfaces, however,
remains mostly unknown and respective in-depth investigations are
missing. Here, we use room temperature scanning tunneling microscopy
to investigate the self-assembly of Y6 at the solid–liquid
interface. We show how coadsorption of polycyclic aromatic hydrocarbon
donor molecules leads to the formation of a series of donor–acceptor
interfacial cocrystals with tailored molecular structure and order
on a graphite surface. The gained understanding of the intricate interplay
of the underlying intermolecular interactions should facilitate the
engineering of multicomponent interfacial nanostructures and help
to potentially improve charge separation and transport in organic
(opto)­electronic devices.