Speaker
Description
This study investigates the relationship between the topology and electrical properties of printed silicon nanoparticle networks, focusing on how variations in cluster size and particle concentration influence charge transport. Silicon nanoparticles were produced via high-energy ball milling and separated into three cluster regimes, 25 μm, 50 μm, and 100 μm, each formulated into inks with concentrations ranging from 45% to 80% by weight. These inks were screen-printed on PET substrates to fabricate test structures for electrical and structural analysis. A suite of characterization techniques was used to elucidate the materials' properties. SEM and HRTEM revealed a polydisperse particle distribution with a strong tendency to agglomerate. The particles were observed to be crystalline. This was corroborated by XRD which further indicated an average crystallite size of 40 - 50 nm. Photoluminescence showed strong red emission around 660 nm (1.88 eV), consistent with defect-mediated recombination and XPS indicated surface oxidation of approximately 2 – 4 %, mainly in the form of sub-oxides, preserving electrical activity. Electrical characterization employed current–voltage and impedance spectroscopy to distinguish intra- and inter-particle charge transport mechanisms. IV analysis showed a transition from non-linear, diode-like, to nearly ohmic behavior as particle concentration increased. Impedance spectroscopy provided evidence of AC-induced transport. Equivalent circuit models evolved from simple CPE to dual-CPE - resistive networks, indicating the presence of distributed relaxation mechanisms. Resonance frequency and effective relaxation times derived from imaginary impedance spectra further confirmed multiple transport regimes, with AC conductivity dominating in sparse networks and DC pathways emerging past the percolation threshold. The study presents experimental evidence of both intra-particle and inter-particle charge transport, as well as distinct regimes of AC and DC conduction. It conclusively establishes the link between nanoparticle topology and charge dynamics, providing a detailed framework for tailoring printable silicon inks in flexible electronics and sensor applications.
| Apply for student award at which level: | MSc |
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| Consent on use of personal information: Abstract Submission | Yes, I ACCEPT |