Ultra-thin, lightweight and flexible solar cells
Mass manufacturing R2R printing technologies can be used to manufacture ultra-thin, lightweight and flexible solar cells that can be customised to any size, shape and electrical performance required in the end-use device.
Thin-film solar cells have numerous applications as autonomous energy sources both indoors and out in harvesting light and converting it into electricity. Solar energy is the only form of renewable energy that can provide a truly autonomous source of electricity through the direct conversion of light into electrical energy via photovoltaic (PV) technology. Light energy is free and abundantly available both outdoors and in. In offices, supermarkets, trade fair halls and industrial estates the lights are always on – this light energy could be utilised to a much greater extent than at present. Additionally, our dependency on easy-access energy sources 'where and whenever' to charge our mobile phones and laptops, our desire to use electronic appliances wirelessly, and our universal desire to be more mobile are driving the development of light energy harvesters and their manufacturing technologies.
R2R manufacturing processes offer great advantage
The main focus area for VTT in the thin-film PV sector has been organic/polymer PV, primarily because in the case of OPV all layers can be solution-processed in an ambient atmosphere and at room temperature using R2R printing or coating techniques. Thus, in OPV no vapour deposition, extensive soaking stages or high temperature steps are required. This provides the following benefits for OPV compared to other thin-film technologies:
Flexible, lightweight and ultra-thin (~200 µm in total)
If printed (not coated), unlimited designs on any shape is possible, giving true design freedom
Large or small area modules possible – customised electrical performance
Design freedom frees your creativity
Using printing methods for the deposition of all layers required in an OPV stack allows direct patterning of all layers and thus printing of any desired shape of cell – and consequently module – without additional processing steps. Individual cells of any shape can be connected in a series or in parallel to form the desired design pattern for aesthetic and end-use design value as well as for the required electrical performance (voltage/current). The design feature of printed OPV is thus not only of aesthetic value but it allows the embedding of a module into an electrical device without limiting the design of the device. This opens up totally new market potential for printed OPV.
As an example of high value non-traditional end use, VTT recently demonstrated an energy-autonomous, decorative presence sensor using printed OPV modules. The leaves harvest energy from indoor light to power different types of presence detectors embedded into a 'painting', and the system then sends this information wirelessly to control indoor lighting, achieving 40-60% savings in energy compared to non-intelligent lighting. The demonstrator illustrates the endless opportunities in design freedom with printed, flexible, designed solar cells and related electronics in such end-use applications.
Towards intelligent systems
Future focus areas for VTT include developing integration solutions for OPV and utilising the existing vast knowledge of thin-film and hybrid integration in traditional electronics. Depending on end-use, the modules can be connected directly to a device or through a storage system. Additionally, control system development adds intelligence to the systems, and plastic in-moulded products, for example, present future potential areas for development.
VTT is your partner in developing light harvesting for autonomous energy source and storage systems to match your requirements throughout the value chain, from materials development for R2R processing and module design to business model development and early market trials. We can support you in finding partners for the whole value chain.