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Papers by michele miliciani

Flexible and Printed Electronics

Polymer thick films compatible with a thermoforming process are the key components to realize the... more Polymer thick films compatible with a thermoforming process are the key components to realize the next generation of HMI and lighting with a 3D custom shape through an in - mold process (Figure 1.). The purpose of this study is to demonstrate that a tailored combination of commercial pastes can offer to the manufacturer more freedom in developing smart electronic devices. A four point probe instrument was used to measure resistivity of the printed circuit. We used the same formed printed sample to estimate level of elongation under the thermoforming process due to the all-in-one screen design developed for the study (Figure 4). The important objective of this work was to form a paste which should withstand such operations without losing physical properties such as conductivity or adhesion or getting lines cracked.

Proceedings of the 8th International Conference on Renewable Electrical Power Sources, 2020

The main goal of the study was to determine parameters for the production of the micro-sized silv... more The main goal of the study was to determine parameters for the production of the micro-sized silver powder applicable to the pastes that are in use in solar cell production and maintenance. In all experiments, silver nitrate solution and ascorbic acid were used, as a silver source and reducing agent, respectively. Polyvinylpyrrolidone and gelatine were used as dispersants. The dispersant in this system acts as a protective agent in a way that prevents agglomeration and aggregation processes. The influence of used agents was different, and one of the aims in the research was to determine the pros and cons of them. The optimal parameters of the synthesis were the solution temperature of 45 °C, pH=7, and concentrations of silver and ascorbic acid of 45 g/l and 30 g/l, respectively. Although PVP has proved to be a suitable protecting agent for the goals of the study, the best results were obtained with the use of gelatine as a dispersant in the concentration ratio against the silver ion...

Energy Procedia, 2013

In this work we propose a detailed investigation of the Al Si interdiffusion that occurs during t... more In this work we propose a detailed investigation of the Al Si interdiffusion that occurs during the firing process of the Al-Si back contact of silicon based solar cells. The investigation is based on high resolution scanning electron microscopy (SEM) and compositional microanalysis with energy dispersive X-Ray microanalysis (EDX). We have found a dependence of Si precipitation in the Al matrix depending on the microstructure of the Al screen printable paste. We suggest a gettering effect promoted by the larger Al particles lying within the Al paste being able to affect the Al paste resistivity, the Al distribution within the BSF region of the solar cell, thus affecting the solar cell performances and finally the Al paste thermal expansion coefficient. Finally we demonstrate that the presence of the glass frit reduces the surface tension and, homogenizes the diffusion process. Reduction of surface tension decreases the internal pressure and increases the Si interdiffusion in Al.

2014 IEEE 40th Photovoltaic Specialist Conference (PVSC), 2014

Amorphous / crystalline silicon heterojunction is the most attractive technique to obtain high ef... more Amorphous / crystalline silicon heterojunction is the most attractive technique to obtain high efficiency solar cells. Usually such a kind of cells is produced starting from n-type silicon wafers, because of several advantages, like the high bulk lifetime and the possibility to easily contact the n-type base with i-n amorphous layers. The emitter is usually covered by Transparent Conductive Oxides (TCO) which works as high conductive layer and Anti Reflection Coating (ARC). The device is completed by a metal grid, made by screen printed silver, sintered at low temperature. Both the TCO and the grid strongly influence the final cell series resistance, and consequently the cell efficiency. When p-type wafer is adopted as substrate for heterojunction cell, the base contact is more difficult to obtain because of the energy bands alignment between the c-Si and the p-type a-Si:H layer. Recently n-type doped SiOx layer has attracted interest as emitter layer in heterojunction device, therefore in this work we show the results obtained on the metallization of n-type SiOx/ptype c-Si heterojunction solar cells by means of low temperature screen printing technique. In particular a new kind of low temperature sintering (<; 200°C) screen printable silver paste has been developed able to ensure high linear conductivity, low specific contact resistivity and strong adhesion to TCO's. We present electrical characterization using Transfer Length Method (TLM) technique. Since the base contact of SiOx/c-Si heterojunction is ensured by laser doping technique starting from p-type a-Si:H layer, we also show how the screen printed Ag paste can enhance the base contact of this solar cell.

Metallurgical and Materials Engineering

Silver nitrate in the solution was reduced in the presence of the dispersants by ascorbic acid, a... more Silver nitrate in the solution was reduced in the presence of the dispersants by ascorbic acid, and silver particles were generated. The main goal was to examine the influence of different dispersants. The purpose was to improve the production process of the micro-sized silver powder for thick film silver pastes for applications in the photovoltaic sector and the printed electronics. Relatively high concentrations of the reagents were used to achieve a high yield of silver particles. It was a strict request for highly economic production. This paper shows the possibilities for the routes for future large-scale synthesis and potential industrial production. The particles were analyzed by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and laser diffraction particle size analyzer.