# Aniline Electropolymerization on Indium–Tin Oxide Nanofilms with Different Surface Resistivity: A Comprehensive Study

## TL;DR

This study explores how aniline polymerizes on ITO surfaces with different resistivity, affecting the quality and properties of the resulting polyaniline films.

## Contribution

The paper provides a systematic analysis of aniline electropolymerization on ITO substrates with varying surface resistivity, a gap in the literature.

## Key findings

- Homogeneous PANI films were produced on ITO substrates with 15–25 Ω/sq resistivity.
- Higher resistivity ITO substrates (70–100 Ω/sq) produced PANI films with better adhesion but less homogeneity.
- Conductive emeraldine salt form of polyaniline was obtained without additional modifications.

## Abstract

Aniline (ANI) was electropolymerized on ITO substrates with different surface resistivities. The process was performed by cyclic voltammetry from an aqueous, homogeneous solution containing sulfuric acid and the aniline monomer using various numbers of cycles and scan rates. The resulting polymer films (PANI) were characterized by ATR-IR spectroscopy, spectroscopic ellipsometry and atomic force microscopy. The influence of ITO surface resistivity on the electropolymerization process, the quality of the obtained PANI layers, and their optical properties was evaluated. Homogeneous PANI films were produced on ITO substrates with surface resistivities of 15–25 Ω/sq, encompassing both emeraldine salt and emeraldine base forms. Although the film’s growth was rapid, it also led to adhesion issues. In contrast, for ITO substrates with surface resistivities of 70–100 Ω/sq and 80–100 Ω/sq, the resulting films showed improved adhesion but were less homogeneous. Nevertheless, the conductive emeraldine salt form of polyaniline was successfully obtained. The conductive form of polyaniline was obtained without any additional modifications to the electropolymerization procedure. Notably, the literature provides no systematic analysis of electropolymerization on ITO substrates with different surface resistivities, which opens up new research opportunities and provides a basis for the rational design and optimization of PANI-based electro-optical coatings for advanced sensing applications.