Hierarchy of adhesion forces in patterns of photoreactive surface layers

TL;DR

This paper demonstrates the use of friction force microscopy to visualize chemical patterns on photoreactive surfaces, revealing multiple surface terminations and their adhesion force hierarchy, which is crucial for organic electronic device fabrication.

Contribution

It introduces a method to visualize and analyze chemical surface patterns inscribed by photolithography using FFM, highlighting the hierarchy of adhesion forces in surface layers.

Findings

FFM can distinguish at least three different chemical surface terminations.

Chemical interaction changes are responsible for contrast in FFM images.

The method enables detailed analysis of surface patterning for organic electronics.

Abstract

Precise control of surface properties including electrical characteristics, wettability, and friction is a prerequisite for manufacturing modern organic electronic devices. The successful combination of bottom up approaches for aligning and orienting the molecules and top down techniques to structure the substrate on the nano and micrometer scale allows the cost efficient fabrication and integration of future organic light emitting diodes and organic thin film transistors. One possibility for the top down patterning of a surface is to utilize different surface free energies or wetting properties of a functional group. Here, we used friction force microscopy (FFM) to reveal chemical patterns inscribed by a photolithographic process into a photosensitive surface layer. FFM allowed the simultaneous visualization of at least three different chemical surface terminations. The underlying mechanism is related to changes in the chemical interaction between probe and film surface.