Patterning of Flexible Transparent Thin-Film Transistors with Solution-Processed ZnO Using the Binary Solvent Mixture

Flexible transparent thin‐film transistors (TTFTs) have emerged as next‐generation transistors because of their applicability in transparent electronic devices. In particular, the major driving force behind solution‐processed zinc oxide film research is its prospective use in printing for electronics. Since the patterning that prevents current leakage and crosstalk noise is essential to fabricate TTFTs, the need for sophisticated patterning methods is critical. In patterning solution‐processed ZnO thin films, several points require careful consideration. In general, as these thin films have a porous structure, conventional patterning based on photolithography causes loss of film performance. In addition, as controlling the drying process is very subtle and cumbersome, it is difficult to fabricate ZnO semiconductor films with robust fidelity through selective printing or patterning. Therefore, we have developed a simple selective patterning method using a substrate pre‐patterned through bond breakage of poly(methyl methacrylate) (PMMA), as well as a new developing method using a toluene–methanol mixture as a binary solvent mixture. Flexible transparent thin‐film transistors are patterned with solution‐processed ZnO. The flexible TTFT including the patterned ZnO as semiconductor was fabricated onto a plastic substrate using a 200 °C annealing process under ambient conditions, as well as a new developing method with a toluene–methanol mixture as a binary solvent. In developing, the toulene‐metahnol mixture induced the uniform and clearly patterned ZnO thin films.