Correlation of optical transmittance with number of graphene layers

Abstract

Optical transmittance of exfoliated multilayer graphene (MLG) was investigated and cross-referenced with a monolayer purchased from Graphene Supermarket USA, #Y060515. The transmittance was found to decrease exponentially with increase in the number of layers. Plots of grayscale values against position on the images from the thinnest edge generated step-like profiles. From the analysis of step heights and step widths, the transition from MLG to bulk graphite occurred at approximately 80 layers. The variations in step heights and step widths with position were attributed to the pressure differences on the surface of the samples during exfoliation, as well as the interlayer interactions within the samples. Our experimental results presented optical transmittance of 97.28, 95.23, 93.23, and 91.28% for a monolayer, bilayer, trilayer and tetralayer respectively. The observed decrease in transmittance with the number of graphene layers is attributed to the variations in optical absorption and reflection of the incident light by the MLG samples.