Functional films underpin many electronic and opto-electronic devices, including flat panel displays, OLED's, image sensors, thin film photovoltaic solar cells, etc. Of particular importance to these devices are transparent conductive oxide (TCO) films, such as indium tin oxide (ITO) and aluminium-doped zinc oxide (ZAO). The UK market for functional films is expected to rise to 23.4B by 2010. Further substantial gains in productivity would be made, and new markets opened up, if the devices could be deposited directly onto polymeric web in very large throughput reel-to-reel coaters. However, the deposition of TCO films onto webs poses many significant technological challenges. In comparison to glass, polymeric webs are relatively rough, tend to outgas significantly and are thermally sensitive. The latter point particularly poses a problem, because it is generally necessary to perform a post-deposition annealing process (typically at 500 degC) in order to optimise the optical and electrical properties of TCO materials.One potential solution to this problem is to deposit coatings using the newly developed technique of high powered impulse magnetron sputtering (HIPIMS). This process involves the application of very large power pulses to magnetron sputter cathodes for short periods of time. The peak pulse power can be in the megawatt range and the pulse duration is typically of the order of 80-160 micro seconds, at repetition rates in the range of 10s to 100s of Hz. Initial studies of the HIPIMS (also referred to as high power pulsed magnetron sputtering / HPPMS) system have shown that this intense pulse creates a high degree of ionization (up to 70% for titanium) of the sputtered species with this technique (in contrast to conventional magnetron sputtering, where usually less than 1% of the sputtered material is ionized).The degree of ionization of the sputtered species in HIPIMS is comparable to that produced in cathodic arc discharges; however, with HIPIMS macroparticles are not normally produced. Another important consideration is that, due to the very low duty cycles (~1%) and long off times, the total heat load to the substrate can be very significantly (5-10 times) lower than in conventional DC and pulsed DC sputtering. Thus, the potential for HIPIMS is to harness the high degree of ionization to produce films with significantly improved properties, whilst maintaining a suitably low (sub-150 degC) substrate bulk temperature, allowing a diverse range of substrate materials to be coated. The introduction of HIPIMS technology, therefore, has the potential to provide a step-change in the performance of functional films, such as TCO's, deposited onto polymeric webs. This project will offer the first opportunity to study this new, complex deposition process in detail in both a development-scale system at MMU and an industrial pilot scale reel-to-reel coater at Oxford University. An additional key element of the project will be a detailed study of the nature of the discharge. Plasma characteristics such as the spatial and temporal evolution of the concentrations and temperatures of the species and their power loading of the substrate will be determined using an array of time-resolved diagnostic tools and well developed optical imaging techniques. The ability to deposit fully dense TCO coatings with optimised properties onto flexible substrates would be a major breakthrough and would represent a significant advancement in web coating technology.

Functional films underpin many electronic and opto-electronic devices, including flat panel displays, OLED's, image sensors, thin film photovoltaic solar cells, etc. Of particular importance to these devices are transparent conductive oxide (TCO) films, such as indium tin oxide (ITO) and aluminium-doped zinc oxide (ZAO). The UK market for functional films is expected to rise to 23.4B by 2010. Further substantial gains in productivity would be made, and new markets opened up, if the devices could be deposited directly onto polymeric web in very large throughput reel-to-reel coaters. However, the deposition of TCO films onto webs poses many significant technological challenges. In comparison to glass, polymeric webs are relatively rough, tend to outgas significantly and are thermally sensitive. The latter point particularly poses a problem, because it is generally necessary to perform a post-deposition annealing process (typically at 500 degC) in order to optimise the optical and electrical properties of TCO materials.One potential solution to this problem is to deposit coatings using the newly developed technique of high powered impulse magnetron sputtering (HIPIMS). This process involves the application of very large power pulses to magnetron sputter cathodes for short periods of time. The peak pulse power can be in the megawatt range and the pulse duration is typically of the order of 80-160 micro seconds, at repetition rates in the range of 10s to 100s of Hz. Initial studies of the HIPIMS (also referred to as high power pulsed magnetron sputtering / HPPMS) system have shown that this intense pulse creates a high degree of ionization (up to 70% for titanium) of the sputtered species with this technique (in contrast to conventional magnetron sputtering, where usually less than 1% of the sputtered material is ionized).The degree of ionization of the sputtered species in HIPIMS is comparable to that produced in cathodic arc discharges; however, with HIPIMS macroparticles are not normally produced. Another important consideration is that, due to the very low duty cycles (~1%) and long off times, the total heat load to the substrate can be very significantly (5-10 times) lower than in conventional DC and pulsed DC sputtering. Thus, the potential for HIPIMS is to harness the high degree of ionization to produce films with significantly improved properties, whilst maintaining a suitably low (sub-150 degC) substrate bulk temperature, allowing a diverse range of substrate materials to be coated. The introduction of HIPIMS technology, therefore, has the potential to provide a step-change in the performance of functional films, such as TCO's, deposited onto polymeric webs. This project will offer the first opportunity to study this new, complex deposition process in detail in both a development-scale system at MMU and an industrial pilot scale reel-to-reel coater at Oxford University. An additional key element of the project will be a detailed study of the nature of the discharge. Plasma characteristics such as the spatial and temporal evolution of the concentrations and temperatures of the species and their power loading of the substrate will be determined using an array of time-resolved diagnostic tools and well developed optical imaging techniques. The ability to deposit fully dense TCO coatings with optimised properties onto flexible substrates would be a major breakthrough and would represent a significant advancement in web coating technology.

Functional films underpin many electronic and opto-electronic devices, including flat panel displays, OLED's, image sensors, thin film photovoltaic solar cells, etc. Of particular importance to these devices are transparent conductive oxide (TCO) films, such as indium tin oxide (ITO) and aluminium-doped zinc oxide (ZAO). The UK market for functional films is expected to rise to 23.4B by 2010. Further substantial gains in productivity would be made, and new markets opened up, if the devices could be deposited directly onto polymeric web in very large throughput reel-to-reel coaters. However, the deposition of TCO films onto webs poses many significant technological challenges. In comparison to glass, polymeric webs are relatively rough, tend to outgas significantly and are thermally sensitive. The latter point particularly poses a problem, because it is generally necessary to perform a post-deposition annealing process (typically at 500 degC) in order to optimise the optical and electrical properties of TCO materials.One potential solution to this problem is to deposit coatings using the newly developed technique of high powered impulse magnetron sputtering (HIPIMS). This process involves the application of very large power pulses to magnetron sputter cathodes for short periods of time. The peak pulse power can be in the megawatt range and the pulse duration is typically of the order of 80-160 micro seconds, at repetition rates in the range of 10s to 100s of Hz. Initial studies of the HIPIMS (also referred to as high power pulsed magnetron sputtering / HPPMS) system have shown that this intense pulse creates a high degree of ionization (up to 70% for titanium) of the sputtered species with this technique (in contrast to conventional magnetron sputtering, where usually less than 1% of the sputtered material is ionized).The degree of ionization of the sputtered species in HIPIMS is comparable to that produced in cathodic arc discharges; however, with HIPIMS macroparticles are not normally produced. Another important consideration is that, due to the very low duty cycles (~1%) and long off times, the total heat load to the substrate can be very significantly (5-10 times) lower than in conventional DC and pulsed DC sputtering. Thus, the potential for HIPIMS is to harness the high degree of ionization to produce films with significantly improved properties, whilst maintaining a suitably low (sub-150 degC) substrate bulk temperature, allowing a diverse range of substrate materials to be coated. The introduction of HIPIMS technology, therefore, has the potential to provide a step-change in the performance of functional films, such as TCO's, deposited onto polymeric webs. This project will offer the first opportunity to study this new, complex deposition process in detail in both a development-scale system at MMU and an industrial pilot scale reel-to-reel coater at Oxford University. An additional key element of the project will be a detailed study of the nature of the discharge. Plasma characteristics such as the spatial and temporal evolution of the concentrations and temperatures of the species and their power loading of the substrate will be determined using an array of time-resolved diagnostic tools and well developed optical imaging techniques. The ability to deposit fully dense TCO coatings with optimised properties onto flexible substrates would be a major breakthrough and would represent a significant advancement in web coating technology.

To be sustainable, energy in our homes and transport needs to be supplied from an inexhaustible source which does not pollute the environment. One such source has been present in our lives since before the formation of planet Earth and will continue to exist for hundreds of thousands of years - it is, of course, the Sun. The light from the sun can be used to make electricity with a solar cell. Every roof top and wall which is lit by the sun can be covered with solar panels and potentially used to make energy. Industry often makes solar cells by taking an everyday material such as glass and coating it with thin layers of semiconductor materials (called absorbers) which absorb light and convert it to electricity. Our research aim is to invent a brand new method for producing solar cell coatings and improve our understanding of the layers. The new method will make solar cells more affordable by using less raw materials and less power during manufacture. It will be applicable to semiconductor materials of today and the future. The new method is based on a technology called HIPIMS (which stands for High Power Impulse Magnetron Sputtering) and is a very recent addition to a family of "plasma" techniques, in which the coating is produced by bombarding the surface you want to coat with carefully prepared atoms and ions. HIPIMS was first discovered in 1995, and pioneering work in our group and elsewhere has already shown that it produces an excellent plasma, with a combination of ion properties which should produce highly efficient solar cells. Our group was the first to use HIPIMS to make solar cells and our early trials do indeed turn out to be very promising. Because it is so new, there are a number of key features of making solar cells by HIPIMS which we do not yet understand. HIPIMS produces a great range of unique and unusual plasmas which create different structures of layers. We are planning to focus our efforts on understanding the link between plasma, structure of the layer and its efficiency in converting light to electricity. Answering these questions would be of interest to scientists who study plasmas, and would help technologists to learn how to apply HIPIMS to create new, better coatings. In the research we will measure properties of HIPIMS plasmas to understand how the composition of the plasma can be changed. We will do this by extracting particles from the plasma and carefully analysing their mass and energy. We will also make coatings using HIPIMS and measure their properties (for example how efficient they are) and examine them under electron microscopes to help our understanding of how the properties relate to the microscopic structure produced by the HIPIMS plasma. In the final stages we will produce large cells in machines used in industry to demonstrate the usefulness of the process not only in science but in business as well. Our experience and understanding should help industrialists to develop manufacturing processes which can generate new, better solar cells. In a few years our houses, cars and mobile phones may all be powered by solar cells developed using HIPIMS!

The market for photovoltaic (PV) solar modules is experiencing astonishing growth due to increasing energy demand, security of supply issues, increasing cost of fossil fuels and concerns over global warming. The world market for photovoltaics grew by 139% to 21GW in 2010. Although this extraordinary pace of growth is unlikely to be maintained in the short term it will advance rapidly again at the point where grid parity is achieved. It is important that the UK retains a strong research presence in this important technology. It is proposed that the SUPERSOLAR Hub of Universities be set up to co-ordinate research activities, establish a network of academic and industrial researchers, conduct cross-technology research and provide a focus for international co-operation. SUPERSOLAR is led by CREST at Loughborough University and supported by the Universities of Bath, Liverpool, Oxford, Sheffield and Southampton. This group is active in all of the PV technologies including new materials, thin film chalcopyrite, c-Si, thin film a-Si, dye sensitised solar cells, organic PV, concentrator PV, PV systems performance and testing. SUPERSOLAR will set up a solar cell efficiency measurement facility for the benefit of the PV community in the UK. The consortium contains a deliberate balance of expertise, with no bias towards any one technology.