Rheology printing for metal-oxide patterns and devices†
Technologies of device printing have been widely explored, but existing printing techniques still cannot produce well-defined patterns required by fine electronic devices. Here, a new printing method is proposed and the printing of metal-oxide patterns with well-defined shapes was demonstrated. Excellent thin-film transistors with channel lengths around 500 nm were completely printed by this method in an air atmosphere. This printing utilizes a viscoelastic transformation of the precursor gel when imprinted; it softens at a certain temperature during thermal-imprinting so that the gel can be rheologically imprinted. The imprinted pattern shows very small shrinkage during post-annealing, thereby achieving a high shape fidelity to the mould; this results from metal-oxide condensation at imprinting. The viscoelastic transformation and metal-oxide condensation at imprinting constitute the basis for this printing method, which is closely related to the cluster structure in the precursor gel. This method has worked for patterns down to several tens of nanometers.