Low‐Cost and Scalable Liquid Metal Printing to Quickly Fabricate High Transparency Ga‐Doped ITO Films

Abstract Transparent conductive oxide (TCO) films, particularly indium tin oxide (ITO) films, are essential in a wide range of optoelectronic applications. However, conventional methods for fabricating and doping ITO films face significant challenges, including high temperatures, vacuum requirements, complex procedures, and high costs. Here a low‐temperature, one‐step liquid gallium–indium–tin printing technique is presented to fabricate Ga‐doped ITO nanofilms. According to needs, In–Sn alloys with varying Sn content can be synthesized and subsequently doped with Ga to form Ga–In–Sn alloys, which then allows printing onto target substrates. Comprehensive characterization reveals that the printed Ga‐doped ITO films exhibit exceptional performances. Specifically, the bandgap of films increases with Ga doping, even reaching 4.81 eV. The transmittance of 1 at.% Ga‐doped ITO films in the visible spectrum exceed 99.82%. While Ga doping increases the resistance of the films, repetitive multilayer printing effectively mitigates this issue. Furthermore, the printed Ga‐doped ITO films embedded into the LED circuit exhibit excellent conductivity. Notably, the films on flexible substrates retain their conductivity even after bending, highlighting their potential for flexible electronics. This liquid metal printing method offers a cost‐effective and efficient alternative to traditional ITO fabrication, with significant promises for future large‐scale optoelectronic device production.