Luís Miguel Nunes Pereira

{We use resonant photoemission spectroscopy (resPES) to study the electronic properties of amorphous ZnO (a-ZnO) layers. We report on the core levels, the valence band (VB) PES data, and the X-ray absorption (XAS) data which we use for the conduction band (CB) density of states. From these results we are able to derive the partial density of states (pDOS) of O2p and Zn4s4p states in the VB and CB, respectively as well as a band scheme. At the O1s resonance we observe a band of localized defect states which is located between the Fermi energy and the CBM. At the Zn2p edge the XAS data indicate that localized Zn4s4p states are involved in the DOS starting already at the Fermi energy. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim}

{Solution processing has been recently considered as an option when trying to reduce the costs associated with deposition under vacuum. In this context, most of the research efforts have been centered in the development of the semiconductors processes nevertheless the development of the most suitable dielectrics for oxide based transistors is as relevant as the semiconductor layer itself. In this work we explore the solution combustion synthesis and report on a completely new and green route for the preparation of amorphous aluminum oxide thin films; introducing water as solvent. Optimized dielectric layers were obtained for a water based precursor solution with 0.1 M concentration and demonstrated high capacitance, 625 nF cm(-2) at 10 kHz, and a permittivity of 7.1. These thin films were successfully applied as gate dielectric in solution processed gallium-zinc-tin oxide (GZTO) thin film transistors (TFTs) yielding good electrical performance such as subthreshold slope of about 0.3 V dec(-1) and mobility above 1.3 cm(2) V-1 s(-1).}

{We report the preparation and spectro-electrochemical characterization of electrochromic devices (ECD) combining inkjet-printed WO3 as cathode and electro-deposited V2O5 as anode. ECD were prepared for the first time with an optimized formulation of gel polymer electrolyte based on Bisphenol A ethoxylate dimethacrylate and Poly(ethylene glycol) methyl ether methacrylate (BEMA/PEGMA) encompassing the Room Temperature Ionic Liquid (RTIL, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) as solvent. The UV-VIS spectrum of ECD was recorded at different potentials during Li+ insertion and de-insertion; additionally the Percent Trasmittance (T%) of ECD vs. time was investigated during repeated bleaching and coloring cycles allowing thus the estimation of switching times and device stability. Due to the lower ionic conductivity and the apparent superior solvent permeability within WO3 active layer, RTIL containing ECD showed slower switching times, but higher contrast with respect to the similar ones with EC/DEC as solvent. These results indicate that the ECD containing environment-friendly RTIL electrolytes are suitable for applications requiring high contrast, high safety and moderately fast switching times.}