Advanced study of structural and optical characteristics of nanocrystalline coomassie brilliant blue G-250 for optoelectronic device optimization

Abstract

This study explores the structural and optical properties of Coomassie Brilliant Blue G-250 (CBBG) using X-ray diffraction (XRD) and spectroscopic techniques. XRD analysis of both powder and thin film samples reveals distinct structural features: the powder exhibits a polycrystalline structure with strong diffraction peaks corresponding to cubic lattice planes, while the thin film shows a mix of crystalline orientations within an amorphous matrix. The Williamson-Hall relation is applied to determine average crystallite sizes, yielding 85.5 nm for the powder and 71.8 nm for the thin film, indicating their nanocrystalline nature. Microstrain analysis also reveals compressive strain within the thin film. These structural insights are critical for understanding CBBG's mechanical and optical properties, vital for biochemical and optoelectronic applications. Density functional theory (DFT) calculations with the B3LYP/6–311++G(d,p) basis set were used to optimize the molecular geometry and analyze HOMO-LUMO energies and reactive sites via the MEP map. CBBG shows higher hyperpolarizability than urea, indicating its potential for nonlinear optical applications. Miller indices further support its optoelectronic optimization. The real (ε₁) and imaginary (ε₂) parts of the dielectric constant were analyzed, revealing CBBG thin films exhibit strong polarization and charge displacement, influenced by structural disorder. Additionally, the volume and surface energy loss functions (VELF and SELF) highlight significant internal energy dissipation, emphasizing CBBG's potential for optoelectronic devices. The complex optical conductivity analysis reveals key absorption and dispersion behaviors essential for advanced photonic and electronic device design.