Light management for the next generation of solar cells. – GENESE

Different approaches are studied in this project:
- The nanostructuring of the substrate / cell via a low cost and replicable on a large scale approach.
- Deposition of thin layer to frequency conversion in which the host matrix acts as effective sensitizer towards rare earth ions that will allow the conversion of a UV photon into two IR photons.
- The fabrication of Ag nanoparticles by various techniques (low energy implantation, Langmuir Blodgett, or magnetron sputtering). The objective is to create a network of metallic nanoparticles acting as a diffuser to increase photon efficiency of the frequency conversion layer.

The results are striking:
1) Development of a simple technique for nanostructuring Si substrate at large scale.
Using the Langmuir Blodgett method for depositing silica beads that will play the role of protection with respect to the substrate. After etching, controlled nanostructuration optimized after modeling as micropillar is obtained.

2) Tb coupling optimization: Yb through a multilayer approach
The emission of Yb3 + ion at 980 nm in a multilayer structure SiNx-Tb / Yb-SiNx was multiplied by two compared with that of a composite film-SiNx Tb: Yb.

If project objectives are achieved during his term, they will constitute for the scientific community, new fundamental bases
The photon conversion, in the case of high quantum efficiency, offers the opportunity to transfer the technology of thin films doped with rare earth ions on current solar cells and therefore, to consider potential industrial and economic benefits. The CIMAP is related to regional or national SMEs that manufacture solar cells (FP2S-renewable energy; Energiz SA; SFER - www.sfer.org) or who need compact systems that can provide the Energy (Greensystech, www.greensystech.com/). IEMN contacts CD2E (www.cd2E.com), Expert Centre for Emerging Environmental Technologies, which developed among others a solar platform Lumiwatt and is tuned for every test or technology transfer innovative. If successful, and after protection of the results, the coordinator agrees to make contact with these companies to explore potential collaborations for future developments.
From a social and economic point of view, these results provide (i) a major breakthrough in the current race to develop solutions in the use of new energy sources, (ii) an opportunity for France to propose innovative solutions to challenges major of tomorrow, (iii) a contribution to the energy independence of France (iv) consistency with the objectives of the Grenelle Environment Forum and the Treaty of Lisbon / Gothenburg.

At present, the project has allowed:
- The submission of an article to Solar Energy Materials and Solar Cells. In correction
- The publication of an article in J. Applied. Physics.
- The achievement of a chapter of a book. «Silicon Nanostructures for Photocoltaics«.
- 3 invited talks at international conferences.
- 4 Oral in international conferences
- 3 posters at international conferences.

There is now a true international economic competition to develop strategic and socio-economic solutions to manage our energy independence as well as our production of greenhouse gas emissions. One of them concerns the production of future low cost solar cells having high conversion efficiency, with the objective of achieving production costs below € 0.5/W by 2030 in Europe. It is in this context that the GENESE project proposes an original approach to allow the conversion of light using a combination of Atomic scale Si sensitizers and/or Ag nanoparticles and rare earth ions coupled to a nanostructuration of the substrate. The objectives are (i) to determine the feasibility of such structures for frequency conversion, and (ii) to identify the most promising structure for sensor such that it benefits from a high absorption cross section and an engineering of the spectral absorption. Such sensors offer a high potential for economic development since the different pathways studied in this project are compatible with the photovoltaic industry.