Nanowires improve solar cell efficiency Recent research has shown that nanowires concentrate the Sun’s energy for higher conversion efficiency than previously thought possible. An EU-funded project has provided several promising nanowire-based solar cell concepts. Energy © Thinkstock Harnessing the Sun’s energy to produce electricity has become a reality in cities across the world. Increasing the conversion efficiency and/or lowering the cost of photovoltaics remains the focus of intense research and development, to truly drive widespread market uptake.EU-funded scientists explored nanowires and other potential efficiency-boosting materials and architectures for state - of - the - art devices within the context of the project ‘Solar cells based on nanowire arrays’ (SOBONA). Scientists studied both nanowire and thin-film photovoltaic structures as well as hybrid architectures employing both. They focused on the use of III-V and II-VI compound semiconductor alloys as well as organic polymers.Nanowire-based solar cells incorporating the superior photovoltaic properties of III-V and II-VI alloys could offer comparable efficiencies with lesser material usage than silicon to significantly decrease cost. Core - shell architectures could eliminate the traditional trade-off between the optical and electrical performance characteristics.The team successfully employed electron-beam lithography, magnetron sputtering and close-space sublimation to grow nanowire arrays. A large number of nanowire formulations based on III-V and II-VI systems were tested resulting in numerous publications. The team also manufactured hybrid structures incorporating nanowires into existing thin-film systems. Several devices demonstrated light conversion efficiency approaching 10 % — close to the world record for nanowire-based cells.Nanowire array preparation and characterisation was supported by theoretical models of growth formation exploiting experimental results. The tremendous quantity of materials, parameters and structures modelled will provide an important basis for development of future systems.SOBONA has delivered a number of promising solar cell concepts based on state - of - the - art nanowire arrays. This should break the current solar cell efficiency and cost barriers to major market uptake. In doing so, technology not only provides a boost to the solar energy sector but makes an important contribution to the health of the planet. Keywords Photovoltaic, solar cell, nanowire, III-V, II-VI, core – shell, thin-film, efficiency, lithography, magnetron sputtering
