PRINTED TRANSPARENT CONDUCTIVE OXIDES FOR ELECTRONIC APPLICATIONS

• Autor(a) principal: Pereira, Tomás Francisco Prior Vicente de Medeiros
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/160454
• topic: Transparent conducting oxide; solution combustion synthesis; green solvents; zirconium-doped indium oxide thin films; Inkjet printing; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

Transparent conducting oxides (TCOs) are nowadays a large market with various important applications specially in the field of optoelectronics, such as LCDs, touch screens, solar panels, among others. Despite the recent advancements, the main processes to produce such materials still employ highly expensive methods based on vacuum environment. This work focusses on the production of In2O3 (the most commonly used material, presenting great optical properties and, after doping, great electrical properties) thin films via solution combustion synthesis (SCS), a low-cost alternative, and is divided in two steps. The first step focussed on producing, via spin coating, the most adequate thin film by changing the indium concentration the number of layers, the solvent, to decrease the environ-mental impact, and the ethylene glycol (EG) concentration, to control the physical properties in prep-aration for the second step. All thin films were doped with Zr, a type-III donor, being the most prom-ising thin film based on ethanol, a green solvent, with a 20% (EG) concentration (V/V) an In2O3 con-centration of 0.2M and 8 layers, that presented high transparency in the visible range (350 nm to 750 nm) of 82.99%, and a bulk resistivity of 2.82 × 10-1 Ω.cm. Focusing exclusively on electrical perfor-mance, the most promising film was a 2-methoxyethanol based film, without EG, for an In2O3 concen-tration of 0.2M and 8 layers presented a transparency in the visible range of 83.85% and a bulk resis-tivity of 9.34 × 10-2 Ω.cm. Once found the most promising thin film conditions (ink viscosity, electrical properties, and environmental impact) the solution based on ethanol was implemented on inkjet printing ensuring a proper deposition. For this phase, UV pre-treatment of the substrate, Z-value, printing resolution (number of dpi) and number of layers parameters were tested. The main property to be analysed in this work is the film uniformity, with promising results being achieved with uniform films being obtained with a UV pre-treatment on the substrate for 15 minutes, a resolution between 400 DPIs and 800 DPIs and a single layer.