Rendering Ti₃C₂T_x (MXene) monolayers visible

Abstract

Herein we report on how to render Ti₃C₂T_x (MXene) monolayers deposited on SiO₂/Si wafers, with different SiO₂ thicknesses, visible. Inputting the effective thickness of a Ti₃C₂T_x monolayer (1 ± 0.2 nm) measured by atomic force microscopy, and its refractive index into a Fresnel-law-based simulation software, we show that the optical contrast of Ti₃C₂T_x monolayers deposited on SiO₂/Si wafers depends on the SiO₂ thickness, number of MXene layers, and the light’s wavelength. The highest contrast was found for SiO₂ thicknesses around 220 nm. Simulations for other substrates, namely, Al₂O₃/Si, HfO₂/Si, Si₃N₄/Si and Al₂O₃/Al, are presented as supplementary information. IMPACT STATEMENT The experimental and simulated color contrasts between Ti₃C₂T_x (MXene) monoflakes deposited on SiO₂ of various thicknesses—under an optical microscope—were obtained for the first time.