Title:
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Injection moulding electroluminescent devices
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Electroluminescence is a developing area of research in the fields of display technology and lighting. Solution based processing of organic materials offers the opportunity to manufacture large area, low cost illuminating surfaces but current processes are limited to two dimensions. The ability to apply electroluminescent materials onto three dimensional contoured surfaces would incorporate the illuminating function into objects, enhancing usability and removing the need for an additional light source. Furthermore, the integration directly into the manufacturing process, such as injection moulding, would have the added benefits of reducing manufacturing time, handling and have environmental and economic savings. Incorporating electronics manufacturing in-mould offers considerable potential for novel research and commercial applications. Electroluminescent multi-layer structures were constructed on 3D surfaces, applying materials using an airbrush. Novel injection moulded electroluminescent devices were successfully made using insert moulding and in-mould layer application techniques, then characterised and compared to a bought device. Electroluminescent layers were also applied to injection moulded plastic parts as a post mould treatment for further comparison. In the current state of development, insert moulding using a PTFE carrier film is the most successful method of injection moulding EL parts, producing devices that light up with an average illuminance of 210.2 39.2 lx when operated at 300 V and 400 Hz. A multi-layer thermal model developed in this project confirms that the injected plastic does not transfer enough heat energy to cure materials that are applied directly in-mould. It was also found that, after 10 weeks, the airbrush made devices maintained 27.3 % points more relative illuminance compared to devices made using a conventional method. Problems associated with all of the new processes have been identified and solutions suggested, but with further research these methods could be used to routinely mould plastic parts with the ability to illuminate.
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