Synthesis, optoelectronic properties and processing of bio-inspired soft materials: Toward new "green" electronic devices

"Green electronics" represents an emerging research area, within the field of organic electronics, aimed at exploiting the potentiality of natural compounds and their derivatives as functional materials for innovative, low-cost and sustainable electronic devices. Starting from this background, the research activity of my PhD has been aimed at the design, synthesis, characterization of the opto-electronic properties and processing of natural and/or Nature-inspired materials for organic light emitting diodes (OLEDs)

An electrochemical study of natural and chemically controlled eumelanin

Eumelanin is the most common form of the pigment melanin in the human body, with functions including antioxidant behavior, metal chelation, and free radical scavenging. This biopigment is of interest for biologically derived batteries and supercapacitors. In this work, we characterized the voltammetric properties of chemically controlled eumelanins produced from 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) building blocks, namely, DHI-melanin, DHICA-melanin, and natural eumelanin, extracted from the ink sac of cuttlefish, Sepia melanin. Eumelanin electrodes were studied for their cyclic voltammetric properties in acidic buffers including Na+, K+, NH4+, and Cu2+ ions

An electrochemical study of natural and chemically controlled eumelanin

ABSTRACT: Eumelanin is the most common form of the pigment melanin in the human body, with functions including antioxidant behavior, metal chelation, and free radical scavenging. This biopigment is of interest for biologically derived batteries and supercapacitors. In this work, we characterized the voltammetric properties of chemically controlled eumelanins produced from 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) building blocks, namely, DHI-melanin, DHICA-melanin, and natural eumelanin, extracted from the ink sac of cuttlefish, Sepia melanin. Eumelanin electrodes were studied for their cyclic voltammetric properties in acidic buffers including Na⁺, K⁺, NH₄⁺, and Cu²⁺ ions. (C) 2017 Author(s)

Effect of surface tension and drying time on inkjet-printed PEDOT:PSS for ITO-free OLED devices

Abstract Highly conductive PEDOT:PSS is one of the most promising materials for indium tin oxide (ITO) substitution in printed electronics. Here, we report the development and optimisation of two PEDOT:PSS ink formulations for the fabrication of inkjet-printed transparent conductive layers. Starting from aqueous commercial solutions, co-solvents and a non-ionic surfactant were employed to modify the surface tension, improve the wetting capability of the ink, and obtain uniform and homogeneous thin films. In particular, the quantities of ethanol and surfactant were systematically adjusted to determine the optimal conditions for inkjet printing. The results demonstrate that a surface tension value between 28 and 40 mN/m and approximately 40 vol.% of a low-boiling-point co-solvent are fundamental to ensure the proper wetting of the glass substrate and a quick-drying process that confers uniformity to the printed thin film. The printed PEDOT:PSS thin films show good morphological, optical, and electrical properties that are similar to those observed for the corresponding spin-coated layers. The organic light-emitting diodes (OLEDs) fabricated with the inkjet-printed PEDOT:PSS electrodes showed a maximum quantum efficiency of 5.5% and maximum current efficiency of 15 cd/A, which is comparable to spin-coated reference devices. These results demonstrate the great potential of polymeric electrodes for the fabrication of high-efficiency printed OLED devices that are compatible with flexible and stretchable substrates

Pressureless sintering of ZnO thin film on plastic substrate via vapor annealing process at near-room temperature

In this work, Vapor Annealing Sintering (VAS) process was introduced for low-cost pressureless producing dense Zinc Oxide (ZnO) thin films deposited from nanoparticles at near-room temperature (50 °C). Spontaneous densification evolution from nanoparticulate to a dense film via a dissolution-diffusion-reprecipitation mechanism was observed exposing ZnO layers to the vapor of an acetic acid aqueous solution at isothermal condition. The influence of the annealing on the optical properties of the treated films was investigated in order to study the structural changes. The proposed method can allow new opportunities for simple and low-cost ceramics thin film manufacturing also involving pressure and temperature-sensitive materials