Applicazioni Elettroniche Conformabili Abilitate da Materiali Avanzati e Nuove Tecniche di Fabbricazione

In recent years, the electronics industry has faced significant challenges in reducing material waste, adopting sustainable fabrication processes, and focusing on new flexible, wearable, and conformable applications. In this framework, new processes and materials have to be considered, going beyond the standard silicon-based technologies and circuits. Solution-processable techniques offer low material waste, primarily due to the absence of mask-based steps during fabrication. These approaches are enabled by the use of organic and nanostructured materials, which are solution processable and exhibit interesting mechanical properties for flexible and conformable applications. In particular, organic materials are characterized by their chemical tunability, while nanostructured materials provide superior electrical performance, such as field-effect mobilities exceeding 100 cm2V−1s−1 in 2D materials (2DMs) semiconductors and low sheet resistivity in metallic nanoparticle suspensions. Despite that, the wide-spread of this technology is still limited by fabrication constraints such as resolution in solution-processable techniques and affinity between different solution-based materials. This thesis faces the challenges of defining conformable applications through different approaches based on the development of solution-processable techniques and materials. First, improvements in resolution of inkjet printing and dip pen nanolithography (DPN) techniques were explored with the aim to define geometric features with a pitch less than 1 μm. This was achieved with the design and fabrication of a versatile prototype of a printing machine capable of depositing or removing materials with micrometre precision. Then, complementary processes such as spin coating and wet/dry transfer and chemical vapour deposition (CVD) were used for the integration of organic and nanostructured materials, such as poly(ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT:PSS), metallic nanoparticles suspensions, poly(vinyl formal) (PVF), MoS2, on flexible substrate, i.e., polyimide and paper, offering a suitable toolset for pliable circuit fabrication. As proof of concept of the technologic solutions developed, high-resolution radio frequency (RF) coplanar waveguides (CPW) structures, conformable field-effect transistors (FETs), and low-cost optical authentication systems based on inkjetprinted physical unclonable functions (PUFs) were fabricated and characterized, both electrically and mechanically. Thanks to the shared fabrication approach and material compatibility, these systems can, in principle, be produced within a unified process flow, offering an integrated, low-cost, low-waste solution for a broad range of electronic applications.