Are MXenes viable as conductive, transparent films for industrial applications?

Two-dimensional transition metal carbides and nitrides, so-called MXenes, hold significant promise as flexible transparent conductive electrodes (TCEs) in diverse applications. However, MXenes fall below the minimum requirements for industrial use, largely due to factors such as the quality of MXene flakes, electrical conductivity, optical conductivity, and transparent electrode fabrication techniques. In this study, we analyze the relationships among nanosheet size, DC- and optical conductivity and its ratio ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>σ</mml:mi> <mml:mrow><mml:mi>DC</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> / <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>σ</mml:mi> <mml:mrow><mml:mi>op</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> ), and sheet resistance (<i>R</i> _s) of MXene TCEs based on data from published literature. Compared to Ti₃C₂T _<i>x</i> TCEs fabricated with low-quality, small-sized flakes ( <1 μm, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>σ</mml:mi> <mml:mrow><mml:mi>DC</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> / <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>σ</mml:mi> <mml:mrow><mml:mi>op</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> < 10), those made with high-quality, large-sized nanosheets ( >6 μm, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>σ</mml:mi> <mml:mrow><mml:mi>DC</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> / <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>σ</mml:mi> <mml:mrow><mml:mi>op</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> > 20) with narrow size distributions exhibit dramatically reduced <i>R</i> _s by several orders of magnitude while maintaining high transmittance. Nevertheless, the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>σ</mml:mi> <mml:mrow><mml:mi>DC</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> / <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>σ</mml:mi> <mml:mrow><mml:mi>op</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> of continuous Ti₃C₂T _<i>x</i> metallic TCEs saturates at ~24, fairly below the basic requirements for commercial TCEs. By integrating a metallic silver grid onto Ti₃C₂T _<i>x</i> TCEs, a remarkable <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>σ</mml:mi> <mml:mrow><mml:mi>DC</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> / <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>σ</mml:mi> <mml:mrow><mml:mi>op</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> ratio of 330 has been achieved, bringing MXene TCEs closer to fulfilling industrial application standards and inspiring greater confidence in their future adoption. Beyond the field of TCEs, the insights gained here could inspire advancements in other areas, such as optoelectronic devices, flexible displays, and energy-efficient transparent technologies. This work provides a framework for the design and development of next-generation transparent conductive materials with broad implications across various scientific and industrial domains.