3D Solar Cells Group: Towards efficient/multi-functional solar energy conversion at lower cost

Abstract
Current single junction photovoltaics (PV) based on traditional semiconductors have almost reached their respective theoretical thermodynamic limits. In order that PV becomes a competitive technology, next generation PV must either overcome the schokley-queisser limit by using new conversion principles, or fabrication processes must be reduced in cost and made scalable. Next generation solar cells are a new domain in the solar energy conversion in which the ratio efficiency-to-cost is significantly increased with respect to traditional bulk and thin film devices. This new technology will be obtained by creating novel device structures, material fabrication processes and implementing new physical conversion principles. In this regard, semiconductor nanowires (NWs) have recently shown their potential for achieving efficient solar energy conversion at low cost. Among the advantages of NWs, are the fact of reduced material consumption, possibility to be obtined on cost-effective substrates and an increased device freedom for optimizing carrier extraction and light absorption in all 3 dimensions. The tuning of the mechanical and optical properties  via their morphology and collective arrangement can enable not only the achievement of new concepts for highly efficient solar energy devices but also provide new functionalities, such as flexible or building integrated PV. However, one of the main concerns about NW-based PV is the large costs in the fabrication process, especially in III-V based materials (like GaAs, InP, etc). In this regard, the group will work towards the development of a new cost-effective technique for semiconductor nanostructures without the need of vacuum systems with the view to impact on energy harvesting and solar energy conversion, and push the frontier of nano-PV. We will combine the dual perspectives of fabrication, engineering and smart design, with the development of a fundamental understanding of the potential benefits and/or limitations that may exist in these structures when used for solar energy conversion.