Synthesis of ultra-large Ti3C2Tx MXene nanoflakes: enabling high-performance flexible transparent conductive coatings

Abstract

Flexible transparent conductive electrodes (FTCEs) are critical components in next-generation wearable electronics and display technologies. However, achieving low sheet resistance without compromising optical transparency remains a significant challenge due to percolation limitations in thin conductive films. MXenes, a rapidly expanding class of two-dimensional (2D) transition metal carbides and nitrides, offer remarkable potential as transparent conducting electrodes (TCEs) owing to their exceptional electrical conductivity, mechanical flexibility, and intrinsically hydrophilic nature. In this work, a modified orbital shaker-assisted Minimally Intensive Layer Delamination (Orbital-MILD) etching method is introduced, yielding ultra-large Ti3C2Tx MXene nanoflakes with an average lateral size of ∼30 µm (optical-microscopy statistics over 168 individual flakes) and individual flakes reaching up to 48 µm – among the largest reported to date for solution-processed MXenes. The gentle orbital mixing action prevents flake fragmentation during both the etching and delamination stages, preserving the large lateral dimensions of the parent MAX phase particles. These large-flake inks were formulated into aqueous colloids and deposited onto flexible polyethylene terephthalate (PET) substrates using slot-die coating – a scalable, alignment-promoting deposition technique. The resultant FTCEs demonstrated an electrical conductivity of 22 777 S cm−1 with a record figure of merit (FoMe) of 39, effectively eliminating the percolation bottleneck common in sparse nanomaterial networks. This work not only addresses a key limitation in MXene-based FTCE fabrication but also opens avenues for extending the method to other MXene systems, enabling scalable production of high-performance flexible electrodes.