  Bottom-up assembly of two-dimensional (2D) materials into macroscale
morphologies with emergent properties requires control of the material
surroundings, so that energetically favorable conditions direct the assembly
process. MXenes, a class of recently developed 2D materials, have found new
applications in areas such as electrochemical energy storage, nanoscale
electronics, sensors, and biosensors. In this report, we present a lateral
self-assembly method for wafer-scale deposition of a mosaic-type 2D MXene flake
monolayers that spontaneously order at the interface between two immiscible
solvents. Facile transfer of this monolayer onto a flat substrate (Si, glass)
results in high-coverage (>90%) monolayer films with uniform thickness,
homogeneous optical properties, and good electrical conductivity. Multiscale
characterization of the resulting films reveals the mosaic structure and sheds
light on the electronic properties of the films, which exhibit good
conductivity over cm-scale areas.
