Photonic Band Gap Engineering by Varying the Inverse Opal Wall Thickness

Area of Science:

• Materials Science
• Nanotechnology
• Photocatalysis

Background:

• Inverse opals offer tunable photonic properties.
• Atomic layer deposition (ALD) allows precise control over material deposition.
• Developing cost-effective fabrication methods for inverse opals is crucial for commercial applications.

Purpose of the Study:

• To demonstrate band gap programming in TiO2 inverse opals.
• To investigate the use of carbon nanosphere templates for cost-effective fabrication.
• To assess the photocatalytic properties of the fabricated inverse opals.

Main Methods:

• Synthesized opal templates using polystyrene and carbon nanospheres via vertical deposition.
• Fabricated TiO2 inverse opals with varying wall thicknesses using ALD.
• Characterized structural and optical properties using SEM, FIB-SEM, EDX, XRD, UV-Vis, and diffuse reflectance spectroscopy.
• Evaluated photocatalytic activity using Raman microscopy, UV-Vis spectrophotometry, and digital photography-based dye degradation tracking.
• Performed Finite Difference Time Domain (FDTD) simulations to analyze photonic properties.

Main Results:

• Achieved band gap programming by controlling TiO2 wall thickness via ALD.
• Carbon nanosphere templates proved effective, reducing costs compared to polystyrene.
• Demonstrated visible light photocatalytic activity in the fabricated TiO2 inverse opals.
• UV-Vis reflectance spectroscopy effectively characterized photonic properties, while diffuse reflectance was less sensitive.

Conclusions:

• ALD enables precise control over inverse opal band gaps for tailored photonic applications.
• Utilizing carbon nanosphere templates offers a pathway to more commercially viable inverse opal fabrication.
• The developed TiO2 inverse opals exhibit promising visible-light photocatalytic performance.