Optical Direct Writing of Solution-Processed SnOₓ Thin-Film Transistors

Tin oxide (SnOx) has attracted considerable attention as a promising metal-oxide semiconductor owing to its high electron mobility, earth abundance, wide bandgap and compatibility with solution processing. However, solution-processed tin oxide thin films generally require complex multi-step photolithography for device fabrication, while insufficient formation of M–O–M networks at low processing temperatures limits film quality and charge transport. Here, we demonstrate a lithography-free direct patterning strategy for high-performance solution-processed SnOx thin-film transistors using direct laser writing. Area-selective optical energy delivery enables localized conversion of precursor films into patterned SnOx semiconductor layers without conventional photolithographic processes. In addition, the introduction of HNO₃ as an oxidizing agent promotes oxide-network formation, leading to improved electrical characteristics and enhanced transconductance.