High Performance of Superconducting YBa2Cu3O7 Thick Films Prepared by Single-Deposition Inkjet Printing

Inkjet printing (IJP) is a very appealing cost-effective deposition technique to achieve large-area solution-derived functional films. For many applications, it is very challenging to increase the film thickness in order to achieve competitive performance, for instance, high critical currents in superconducting films. In this paper, the preparation of superconducting YBa2Cu3O7 thick films (similar to 1.1 mu m) using a single deposition is reported. Specific rules for ink design, deposition protocols, and pyrolysis processes are provided. The most important aspect is to formulate an ink with a solvent having a high boiling point that keeps the whole film wet during deposition to avoid liquid movement due to coffee-ring effects. An additional success has been to modify the ink with a photocurable polyacrylic ester varnish which after polymerization with a UV LED lamp helps keep homogeneous thickness. This varnish also helped avoid the generation of film instabilities (wrinkling or cracking) during pyrolysis. Homogeneous pyrolyzed thick films are transformed into epitaxial thick films with high critical currents. The IJP process is shown to be valid to prepare nanocomposite films using colloidal inks including pre-prepared BaZrO3 nanoparticles. The nanocomposite thick films display enhanced vortex pinning, thus keeping high critical currents under high magnetic fields.

Automated summary

This paper introduces a method for preparing superconducting films using inkjet printing technology, including ink design, deposition protocols, and pyrolysis process, successfully achieving the preparation of superconducting thick films with a thickness of 1.1 micrometers. By using ink with a high boiling point solvent and modifying the ink with photocurable varnish, issues like liquid movement and film instabilities during pyrolysis are avoided, ultimately obtaining thick films with high critical currents.