M.A. Torres Arango, K.A. Sierros
West Virginia University,
Keywords: additive manufacturing, flexible electronics, energy applications, properties-processing relating
Summary:Innovations in materials and manufacturing are important enablers of new technologies across multiple engineering fields. Additive manufacturing comprises a group of revolutionary fabrication techniques, having as principle the addition of materials layer-by-layer to form a desired device design. Among the printing techniques encompassed by additive manufacturing, continuous-flow direct writing represents an important route towards the fabrication of novel flexible electronics. This versatile lithography-free method, enables the fabrication of complex 2D and 3D architectures, with virtually no material waste, by pneumatic deposition of functional inks through a nozzle on digitally pre-defined substrate locations. In this presentation we will discuss our recent advances in the development of robotic printers, and the synthesis and processing of different conductive and semiconducting materials inks. Also, we will address the development of highly mesoporous material foam structures utilizing continuous-flow direct writing. Special emphasis is placed on developing environmentally-friendly inks for enhancing the sustainability of manufacturing and reducing the use of harmful solvents. Furthermore, the directly written structures’ properties are investigated, after exposure to different curing/sintering mild conditions such as electrical sintering, UV radiation, and/or low temperatures (below 150 Celsius). Characterizing and understanding the resulting properties, with respect to processing conditions, is necessary to control mechanical, thermal, and chemical characteristics of the printed structures. The proposed treatments aid towards industry-transferable solutions for low-temperature fabrication, compatible with flexible polymer substrates. Highlights of our projects include the investigation of the optical, electron transport, mechanical, microstructural, and surface chemistry properties of Ag micro-patterned electrodes, TiO2-based films and printed foams, and ZnO-based photosensitive structures. It is believed that novel patterning of functional optoelectronic nanomaterials using continuous-flow direct writing may hold the key for the next generation of low-cost, large-area, flexible optoelectronic devices for energy applications. Building on this, the understanding of the relationships between processing and properties, are of paramount importance for the scale-up and industrial adoption of such approach.