Abstract: The growing demand of new and sustainable consumer printed electronics led to the increased interest in electric and electrochemical devices on paper substrates. Here we present the work resulting from recent research concerning the combination of oxide nanoparticles and carbon fibers with cellulosic materials. The first topic is related with printed layers composed of carbon fibers and carboxymethyl cellulose that can be used both as humidity and temperature sensors, with distinct response, resulting in thermistors with a sensitivity of 0.079 ̊C-1 and a hygristors where resistance changes by a factor of 15 when relative humidity varies between 10 to 60 %. Cellulose derivates can also be used in printable inks based on commercial ZnO nanoparticles that were optimized to create semiconductor layers at temperatures lower than 150 °C. This allowed the development of fully screen-printed electrolyte gated transistors on paper with mobility above 1 cm2V-1s-1 and on/off current ratio close to 104. The performance of these devices can be further improved when using a new solid-state electrolyte also based on cellulose. These membranes present ionic conductivity close to 10-3Scm, resulting in improved switching frequency and reduced hysteresis on the transistors. An important feature of such membranes is the possibility to detach them from the substrate, re-use and recycle/regenerate them, without affecting the final characteristics of the transistors. Finally, we will present our activity related to nanostructured printed layers based on dual phase films. Electrochromic printed layers based on WO3 nanoparticles optimized by design show an optical density 80% higher than amorphous ones, in parallel with improved coloration efficiency and response time (below 3s). The dual phase approach can also be used to prepare inks that can be written on paper, resulting in dense ZnO nanoparticles matrix with sufficient interparticle connectivity to be used in hybrid handdrawn/printed UV-sensors, transistors and logic gates.
Bio: Prof. Luis Pereira was born in Lisbon, Portugal, in 1977. He received an Engineering degree in Materials Science in 2001 and finished a Ph.D. in Microelectronics and Optoelectronics in 2008 at Universidade Nova de Lisboa. His Ph.D. work was focused on polycrystalline silicon and high k dielectrics for TFT’s application. The expertise gained on oxide materials for electronics allowed focusing the postdoc activities on the development printed inorganic nanostructured materials for chromogenic, electronic and electrochemical devices on paper and plastic substrates. He was involved in the team that demonstrated for the first time transistors made of oxides with paper as dielectric. He has authored and co-authored 163 publications in peer-reviewed journals and proceedings of the ISI with more than 4500 citations and has a H factor of 33. He is currently Associate Professor at DCM-FCT/UNL and researcher at CENIMAT/I3N where coordinates and participates in R&D projects. He has been granted in 2015 with a Starting Grant of the European Research Council (ERC) on the development of cellulose nanocomposites for paper electronics (New-Fun, project 640598). His current research interests are on the design and synthesis of 1D, 2D and 3D inorganic and hybrid nanostructures, chiral cellulose nanocomposites, functional micro and nanofibers and it integration on chromogenic, electronic and electrochemical devices.
For additional information, please contact Professor Aaron Mazzeo at email@example.com or 848-445-0504.