E-Thesis 131 views
The Electrodeposition of Polymers and Luminescent Materials to Create the Next Generation of Lighting Technology / SAMUAL NGOMBE
Swansea University Author: SAMUAL NGOMBE
Abstract
This thesis is an account of an experimental investigation into the manufacture of electroluminescent lighting with 3D geometry. The study required extensive experimentation into the electrophoretic deposition process and its suitability to a complex 3D substrate as opposed to 2D. The research requi...
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Swansea, Wales, UK
2023
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| Institution: | Swansea University |
| Degree level: | Master of Research |
| Degree name: | MSc by Research |
| Supervisor: | Phillips, Christopher O., Deganello, Davide. and Leak, Peter. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa63610 |
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| Abstract: |
This thesis is an account of an experimental investigation into the manufacture of electroluminescent lighting with 3D geometry. The study required extensive experimentation into the electrophoretic deposition process and its suitability to a complex 3D substrate as opposed to 2D. The research required the development of a novel experimental technique in which multiple surfaces of the substrate may be coated. The experimental set-up required alteration from the original design supplied by the sponsoring company to a singular cylindrical electrode developed through literature research. The layers of the emissive source that were experimented on consisted of a Barium Titanate (BaTiO3) dielectric, phosphor trimix (CaS:Eu, ZnS:Ag and ZnS:Cu, Al) emissive layer and a Poly(methyl methacrylate) (PMMA) encapsulating polymer layer. Upon successful results from this novel experimental set up, parameters such as applied voltage, processing time (the period that the substrate is submerged in the suspension and the power source is initiated) and solid concentration were tested in a range of combinations. Extensive experimentation allowed for optimal parameters to be found for each layer. BaTiO3 exhibited preferable deposit morphology at a bulk concentration of 20-25 g/L and the addition of adhesion-promoting polymer Polyvinylpyrrolidone (PVP) formed a high-quality, uniform deposit. The electrophoretic deposition of the phosphor layer was improved through sieving to a particle size range of 4-11 μm. This allowed for a reduction in particle size distribution to make particle mobility more predictable and improve material suspension. Agitation of the phosphor material was found to be important in maximising deposited material. A stirring rate of 315-390 rpm would encourage the most uniform deposit. Electrophoretic deposition of the encapsulating polymer was unsuccessful due to electrolysis causing hole formation in the deposited layer at the anode. Due to this, a dip coating process was established and was successful in achieving material deposit whilst improving the adhesion of the previous layer. Electrophoretic deposition onto a 3D substrate was successful and it is now possible to coat an entire coil from outside to inside face simultaneously. After optimal conditions were found for the individual layers, sequenced deposition of the dielectric, phosphor and encapsulating polymer layers was also carried out successfully. Parameters required further adjustment to account for the increased system resistance due to material deposit. The preliminary stages of testing electrodeposition of the 3 materials have proven to be a promising method in the fabrication of an alternating current electroluminescent (ACEL) device. |
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| Keywords: |
Electrophoretic deposition (EPD), Alternating current electroluminescence (ACEL) |
| College: |
Faculty of Science and Engineering |