Mapping Polymer Molecular Order in the SEM with Secondary Electron Hyperspectral Imaging

Area of Science:

• Materials Science
• Organic Electronics
• Spectroscopy

Background:

• Understanding nanoscale molecular order is key for developing advanced organic electronic devices.
• Current imaging techniques for molecular order in polymers lack sufficient resolution, accuracy, and accessibility.
• Poly(3-hexylthiophene) (P3HT) is a widely studied polymer in organic electronics.

Purpose of the Study:

• To introduce secondary electron (SE) spectroscopy and hyperspectral imaging as novel methods for probing molecular ordering in P3HT.
• To demonstrate the capability of SE spectroscopy to reflect the crystalline content of P3HT films.
• To utilize machine learning for accurate mapping of crystalline regions within P3HT films.

Main Methods:

• Secondary electron (SE) spectroscopy and hyperspectral imaging using a scanning electron microscope.
• Correlation of SE spectroscopy with nano-Fourier-transform infrared spectroscopy.
• Experimental and modeling approaches to investigate SE spectral features.
• Application of machine learning algorithms for image analysis.

Main Results:

• SE energy spectrum of P3HT films empirically correlates with crystalline content.
• Distinct SE energy distributions arise from the different electronic properties of amorphous and crystalline P3HT.
• Hyperspectral SE imaging successfully visualizes localized molecular orientation.
• Machine learning accurately identifies and maps crystalline content in P3HT films.

Conclusions:

• SE spectroscopy and hyperspectral imaging offer a powerful, accessible, and high-resolution alternative for characterizing molecular order in organic electronic materials.
• The technique provides valuable insights into the relationship between molecular structure and electronic properties.
• This approach facilitates the development of improved organic electronic devices through precise material characterization.