Highly Conductive Optical Quality Solution‐Processed Films of 2D Titanium Carbide

TLDR

MXenes are a new class of solution‑dispersible, two‑dimensional nanomaterials derived from transition‑metal carbides and nitrides such as Ti₃C₂. Spin‑cast aqueous Ti₃C₂ films achieve 6500 S cm⁻¹ conductivity and >97 % visible transmission per nanometer, surpassing other solution‑processed 2D materials, with the high conductivity arising from free‑electron density and coplanar nanosheet alignment, and optical measurements reveal plasma oscillations above 1130 nm, positioning Ti₃C₂ as a promising near‑infrared plasmonic and optoelectronic material.

Abstract

MXenes comprise a new class of solution‐dispersable, 2D nanomaterials formed from transition metal carbides and nitrides such as Ti 3 C 2 . Here, it is shown that 2D Ti 3 C 2 can be assembled from aqueous solutions into optical quality, nanometer thin films that, at 6500 S cm −1 , surpass the conductivity of other solution‐processed 2D materials, while simultaneously transmitting >97% of visible light per‐nanometer thickness. It is shown that this high conductivity is due to a metal‐like free‐electron density as well as a high degree of coplanar alignment of individual nanosheets achieved through spincasting. Consequently, the spincast films exhibit conductivity over a macroscopic scale that is comparable to the intrinsic conductivity of the constituent 2D sheets. Additionally, optical characterization over the ultraviolet‐to‐near‐infrared range reveals the onset of free‐electron plasma oscillations above 1130 nm. Ti 3 C 2 is therefore a potential building block for plasmonic applications at near‐infrared wavelengths and constitutes the first example of a new class of solution‐processed, carbide‐based 2D optoelectronic materials.