Cost-effective, high-efficiency solar cells Harvesting the Sun's virtually limitless supply of energy is an incredibly sustainable way to reduce dependence on fossil fuels. Novel technologies developed with EU funding promise to enhance widespread market uptake. Energy © Thinkstock Silicon (Si)-based photovoltaic (PV) devices can now be seen on rooftops and solar farms across Europe, yet widespread implementation is hindered by costs and limits in efficiency. The EU-funded project 'Nanomaterials and nanotechnology for advanced photovoltaics' (NANOPV) addressed current bottlenecks in production with large-scale processes and equipment for production of PVs from nanomaterials. The consortium studied a large variety of such materials from zero-dimensional quantum dots, nanocrystals and nanoparticles, to 1D nanowires and nanorods and even 2D ultra-thin nanolayers. In addition to materials' development to enhance efficiency, scientists developed cost-effective large-scale processes and equipment for integration into existing pilot and industrial production lines. Nanomaterials can significantly enhance efficiencies by making better use of the electromagnetic spectrum, taking advantage of a broader range of available wavelengths. More than 20 % energy conversion efficiency was targeted for wafer-based Si devices and more than 15 % for epitaxially grown thin-film Si solar cells. Scientists also assessed low-cost solar cells produced entirely from nanomaterials. Of the more than 50 materials tested, 9 were integrated in wafer-based Si devices and 11 in thin-film Si solar cells. Enhanced conversion efficiency was seen in some cases. A database of the most promising candidates has been created and several were chosen for optimisation within the project. For instance, the team optimised fabrication of solar cells with Si nanorod/nanowire structures. This resulted in thin film solar cells of high efficiency (10 %) that can be produced cost effectively at industrial scale. In addition, incorporation of Si-based nanolayers into Si-based solar cell structures resulted in high conversion efficiency for both wafer-based (> 20 %) and epitaxially grown thin-film (~ 15 %) architectures. NANOPV demonstrated the feasibility of high-efficiency, low-cost PV devices using nanomaterials. The project has contributed to development of a safe, cost-effective and sustainable energy supply with technologies that will enhance the competitive position of the EU in a market poised for a major breakthrough. Keywords Solar cells, silicon, photovoltaic, nanomaterials, nanowires, nanorods
