Maskless deposition of patterned transparent conductive oxides via laser-assisted atmospheric pressure plasma jet

Transparent conductive oxides (TCOs) are indispensable as transparent electrodes in optoelectronic applications due to their unique features of high optical transmittance, high electrical conductivity, and cost-effective industrial-scale manufacturability. However, patterning TCO films for functional devices requires lengthy and expensive photolithography and etching processes. Although the laser patterning technique—based on nanoparticle ink and particle-free ink—has been used to fabricate patterned metal electrodes without photolithography, it is still unknown if it works for TCO, such as doped zinc oxide (ZnO). Here, we introduce a novel single-step maskless, particle-free, and ink-free process to deposit transparent, conductive Ga-doped ZnO (GZO) patterns on glass substrates via a laser-assisted atmospheric pressure plasma jet (APPJ) technique. With the exposure of a plasma jet, GZO patterns can be deposited by scanning a continuous-wave CO₂ laser using a galvanometer and computer-aided design (CAD) images. The GZO patterns (∼100 nm thick) are visually transparent and exhibit remarkably low resistivity of 7.89 × 10^–4 Ω cm, comparable with that of uniform (unpatterned) GZO films prepared by APPJ only. Our present work fundamentally differs from prior works since neither particles nor ink is applied to the substrate before processing. The entire process is conducted in ambient conditions without substrate preheating and pre-/post-processing. Also, it does not require expensive vacuum apparatus and pulsed laser sources and has a high potential for cost-effective and sustainable fabrication of TCO patterns and circuits.