High-throughput optical thickness and size characterization of 2D materials

Area of Science:

• Materials Science
• Nanotechnology
• Optical Physics

Background:

• Characterizing nanosheet materials like graphene oxide (GO) is crucial for understanding their properties.
• Traditional methods such as atomic force microscopy (AFM) are time-consuming and limit high-throughput analysis.
• Inhomogeneities in samples often hinder accurate optical characterization.

Purpose of the Study:

• To develop a faster, more efficient method for characterizing large populations of nanosheets.
• To enable robust statistical analysis of nanosheet properties, including atomic layer count and lateral size.
• To assess the utility of the method for analyzing graphene oxide (GO) and its oxidation levels.

Main Methods:

• Utilizing simple optical microscopy combined with advanced image processing techniques.
• Implementing an image normalization method based on substrate brightness to overcome optical inhomogeneities.
• Applying the technique to analyze fractions of emulsion-based graphene oxide (GO) samples.

Main Results:

• Simultaneous characterization of thousands of nanosheets within a 1 mm² area.
• Determination of atomic layer number and lateral sizes for all sheets within hours, a ~100x speed improvement over AFM.
• Successful analysis of GO samples, providing morphological composition and insights into oxidation levels and optical constants.

Conclusions:

• The developed optical microscopy method offers a significantly faster and more robust approach for nanosheet characterization.
• This technique facilitates comprehensive statistical analysis of nanosheet populations, crucial for materials discovery and development.
• The method's sensitivity extends to determining material properties like oxidation level and optical constants, broadening its applicability.