Determining the Dielectric Tensor of Microtextured Organic Thin Films by Imaging Mueller Matrix Ellipsometry

Area of Science:

• Materials Science
• Optics
• Solid State Physics

Background:

• Polycrystalline textured thin films exhibit unique optical properties like pleochroism and birefringence.
• Anilino squaraine derivatives, specifically with isobutyl side chains (SQIB), are of interest for their potential in optical applications.

Purpose of the Study:

• To analyze the biaxial dielectric tensor of polycrystalline textured SQIB thin films.
• To investigate the relationship between molecular structure, intermolecular interactions, and optical properties.

Main Methods:

• Imaging Mueller matrix ellipsometry was employed for detailed optical analysis.
• Simultaneous fitting of transmission and reflection Mueller matrix scans was performed.
• Spatial resolution of an optical microscope was utilized for accurate tensor determination.

Main Results:

• The full biaxial dielectric tensor was accurately determined from a single crystallographic orientation.
• Oscillator dispersion relations effectively modeled the dielectric tensor components.
• Strong intermolecular interactions led to a strongly negative real permittivity near excitonic resonances.

Conclusions:

• The study successfully characterized the optical properties of SQIB thin films.
• The determined dielectric tensor and observed negative permittivity are highly promising for nanophotonic applications.