Background Recent developments in nanotechnology are leading to displays that are cheaper, larger, brighter, and more efficient than current ones. A more radical display technology would form an image directly on the retina. An interesting combination of the old and the new is provided by so-called electronic inks; these combine the crispness and contrast of printing onto paper with the switch ability of an emissive or liquid crystal display. Particles of electronic ink can be switched from black to white by the application of an electrical field. Reproducing Computer Output Usually the output from a computer is now an image or a piece of text, but since computers are used so frequently to design artefacts, it would be useful to provide an output that was the three-dimensional artefact itself. Various technologies for rapid prototyping achieve just this goal. This can be done by repeated ink-jet printing using, instead of ink, a material that solidifies after printing, to build up a three-dimensional image made from plastic. Alternatively, a container of liquid monomer can be scanned by a laser beam, whose light initiates the polymerisation of the monomer to form a solid plastic object. This reflects the fact that efforts in the information technology industry have been devoted to increasing performance almost at any cost (speaking here of the capital cost of semiconductor plants). Developments In Plastic Electronics One area moving against this trend is the field of plastic electronics, in which semiconducting polymers are used as the active materials to make logic circuits and display devices. Semiconducting polymers have significantly worse electronic properties than conventional semiconductors like silicon or gallium arsenide. But they are very cheap to make. Rather than using expensive lithography to pattern them to form circuits, very cheap processes such as ink-jet printing or soft lithography can be used. They can also be made into devices that are flexible. Polymer Light Emitting Diodes Firstly, polymer light emitting diodes have been commercialised already; the potential here is for large area, flexible display devices such as roll-up computer or TV screens to be made cheaply. Entirely new products, such as clothing with an electronic display, can also be envisaged. Secondly, field effect transistors are the basic element of logic and memory circuits, so very low cost printed logic circuits would be possible, with potential applications in packaging. Development Of Solar Cells One can imagine a radio frequency ID device being incorporated in packaging or in an artefact that would identify itself and announce its presence. This would have a major impact on the way supply chains are managed in manufacturing industry, retail and distribution. Finally, being actively researched, but currently furthest away from commercialisation, are photovoltaic devices, such as solar cells. In fact solar cells made from semiconducting polymers form just one class of novel solar cell architectures made from unconventional nanostructured semiconductors; Grätzel cells, made from nanosized titanium dioxide particles (a cheap and widely available substance which is the major pigment in white paint) sensitised by organic dyes are another example, and variants are being experimented with which use C60 particles. Once again, the efficiencies and lifetimes of these unconventional solar cells currently compare poorly with conventional materials based on inorganic semiconductors. Economics Concerning Renewable Energies However, if significant improvements can be made the processing technologies that would be available to make very large areas of material cheaply could transform the economics of renewable energies, bringing down the cost of energy generated by solar cells towards the cost of non-renewable sources such as gas and oil. |