High Efficiency Solid State Light Sources Deposited by HITUS

We live in a world where the rapid development of Information & Communications Technology has led to an evolution in the way we work and communicate with each other. New personal communication devices and wireless networks are changing our daily lives and opening up potential for innovation and creativity. Much of this is due to the exciting new developments in the various component, or `enabling' technologies that are at the heart of the ICT revolution. In particular, visual display systems, wireless technology, and the convergence of portable devices into single hand-held units are driving this technological revolution. Another very important factor which has ensured the broad uptake of these technologies is the reduction in cost and the ability to mass produce sophisticated portable systems on an economical scale. For the next generation of systems and enabling technologies, there is a desire to move to what is known as `plastic electronics', or `flexible electronics'. In essence, this means the fabrication of state-of-the-art microelectronics and visual display systems onto plastic substrates, rather than the silicon wafers and glass substrates that are currently the norm. The reasons for this include; 1. a reduction in overall costs, with the possibility of reel-to-reel production, and 2. the option of roll-up and conformable displays & electronic devices. Imagine, for example, being able to open up an A4 sized display screen from a unit that can be rolled up into the size of a large pen. Sounds interesting, and is certainly of interest to the electronics and printing industries in the UK, but what are the challenges ? Well, one very important issue, particularly for the display and lighting sectors, is the need for component layers that can be deposited onto plastic substrates with the required electrical and optical properties, but where these `thin films' are robust enough to withstand the actual flexing of the substrate. This is not as straightforward as it sounds, because the most important material for this type of application - a transparent conducting layer called ITO, is very brittle and cracks when put under strain. In addition, the electronic materials used in displays etc., such as ITO, are typically deposited onto substrates (e.g. glass) held at temperatures in excess of 200 degrees C., in order to get the required properties. Not a good idea when using temperature sensitive plastic substrates. The project proposed here will address these issues by using a novel deposition technology (called HiTUS) that has been developed in the UK . This technology provides a much tighter control of material parameters as the deposition occurs, and has the potential to produce high quality, crack resistant, ITO, at low temperatures - suitable for plastic substrates. The HiTUS Light Source project is a collaboration between the company who invented this deposition technology - Plasma Quest Ltd., and Nottingham Trent University, who are experts in thin film display devices and laser processing of materials. Work at NTU has been concerned with `phosphors' - the materials that emit light in TV's, Plasma screens, and fluorescent lamps. These materials are important for use in flexible light emitting devices, and this project will thus investigate the use of the novel HiTUS technology to optimise both the ITO and phosphor layers for a range of potential flexible displays and lighting applications. A further aspect of this project will be an investigation into the novel use of laser patterning of the layers to fabricate devices on plastic with a process that is much more efficient than the multiple step pattern and etch processes that are currently used. The project will therefore combine the expertise of the two partners to develop new knowledge that will open up a world of opportunity in the development of future flexible -electronics, displays and lighting.