SNAPSUN · Semiconductor Nanomaterial for Advanced Photovoltaic Solar cells Using New concept of nanocrystal and conductive host

Renewable energy production is a key driver for innovation in the material domain. Researchers and industries look to reduce the energy cost and to increase the efficiency of PV solar cells. Nanotechnologies and nanomaterials show broad opportunities. Indeed, at the nanoscale level, energy band gaps depend on nanomaterial architectures (nanoparticles size, bulk dispersion, interfaces with embedding matrix). Silicon nanocrystals allow the design of highly efficiency architectures, like multijunction solar cells or low-cost, optimised, thin film solar cells. The usual elaboration technique is based on the deposition of either multilayer or nanocomposite material in which excess silicon is aggregated into nanoparticles through high temperature annealing. No control of nanoparticle size and bulk dispersion is possible. Moreover, only limited surrounding materials could be considered (silicon containing). This prevents any knowledge-based tuning of the material properties. The main objective of SNAPSUN project is to develop a nanomaterial with reliable and tailored characteristics. To overcome limitations described above, fully tailored silicon nanoparticles will be optimised, in terms of size (3nm) and size dispersion (>10%;0.3nm). The SNAPSUN innovation is the incorporation of these silicon nanoparticles in a wide band gap material, such as silicon carbide or Transparent Conductive Oxides (TCO). This architecture will allow band gap engineering through accurate structure control, together with exceptional electrical characteristics (resistivity, carrier lifetime, etc.) in order to produce high conversion efficiencies above 25 %. Control of material structure will arise from the development of very promising processes allowing the separation of nanoparticle generation and embedding matrix codeposition. Vacuum and wet technologies will be used to target low-cost solar cells with a target production cost below 0.5 €/Wpeak.