Poitiers, France
Poitiers, France

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Grant
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: NMP-2010-1.2-3 | Award Amount: 4.01M | Year: 2011

The project aims at developing Nanoparticle Embedded in Alloy Thermoelectric (NEAT) materials to harvest energy in the KW range. Thermoelectric Generators will help to recover some of the huge amount of wasted high-grade thermal power leading to significant savings in fuel and Green House Gas emissions. These innovative materials will be designed to perform efficient waste heat recovery in high thermal differentials provided by high temperature industrial processes and automotive engines. Conventional thermoelectric materials are toping ZT values of 1 since several decades. Recently, ZT values as high as 3 at 550K have been reported for thin film nanostructured materials. However, bulk materials are far from reaching a similar performance. NEAT is an innovative nanocomposite alloy capable of attaining ZT>3 at high and medium temperatures. The material concept is based on the joint optimization of nanoinclusions and grain boundaries in order to maximize phonon scattering at multiple length scales, without increasing electron scattering significantly. NEAT will focus on: - Mg2Si nanoparticles in n-Mg2SiSn alloy matrix, for medium temperature range (500-800K) - Ge and Silicide nanoparticles in SiGe alloy matrix, for high temperature range (900-1200K) - A graded nanocomposite of both medium and high temperature materials, for high thermal gradients accommodation. The concept achievement will require manufacturing process innovations enabling the inclusion of well controlled nanoparticles in a host polycrystalline alloy and the preservation of the initial architecture during the sintering. It will benefit from advanced theoretical simulation providing fundamental physical understanding, and materials development guidance. The demonstration of the nanocomposites thermoelectric performances in proof of concept thermoelectric generators and the assessment of its energy pay-back will unambiguously state the potential industrial impact of the project outcomes.


Bellanger P.,Lyon Institute of Nanotechnologies | Bellanger P.,Societe sTile | Sow A.,Societe sTile | Sow A.,University of Poitiers | And 8 more authors.
Journal of Crystal Growth | Year: 2012

In the present work, a recrystallization process of sintered silicon wafers was studied to produce photovoltaic solar cells. The recrystallization step is carried out by Zone Melting Recrystallization (ZMR) or Full Wafer Recrystallization (FWR). Structural analysis and impurity content of the processed material are presented. Electrical characterization shows that mobility reaches values of 150 and 250 cm 2 V -1 s -1 in samples recrystallized by FWR and ZMR with P-type doping of 5×10 16 and 3×10 17 at/cm 3. The lifetime reaches values around 1 μs. After solar cell fabrication, a conversion efficiency of 8.9% is obtained by using a simplified process without texturing. © 2012 Elsevier B.V.


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2010.10.2-1 | Award Amount: 3.90M | Year: 2010

The current technologies to produce photovoltaic modules exhibit features, which prevent cost-reduction to below 0,5/Wp: - Sawing/Wafering and Module assembly is costly and material intensive for wafer solar cells - Efficiency is comparatively low for classical thin-film solar cells (CdTe, CIS, a-Si/c-Si, dye, organic). One approach to avoid both disadvantages is the so-called crystalline Si thin-film lift-off approach, where thin c-Si layers are stripped from a silicon wafer. This approach has the potential to reach > 20% efficient solar cells, however handling issues stop quick progress so far. The basic idea of the current project is to enable the use of lift-off films in a nearly handling-free approach, to avoid limitations by handling issues. The technological realization has the following key features and steps: - Continuous separation of a very thin (< 10 m) c-Si foil from the circumference of a monocrystalline silicon ingot - Attachment to a high-temperature stable substrate of large area (e.g. graphite, Sintered Silicon, or ceramics), which can also serve as module back side. - High-temperature re-organisation of the silicon foil followed by in-situ epitaxial thickening (~40 m base thickness) in an in-line chemical vapour deposition reactor, including pn-junction formation - Processing of high-efficiency solar cells and formation of integrated interconnected high-voltage modules - Encapsulating into a module (glass / encapsulant only if needed) The resulting module to be demonstrated in R2M-Si has a cost potential around 0.55 /Wp, at 18% module efficiency and thus low Balance-of-System cost. Future enhanced R2M-Si modules can exceed even 20% efficiency, at costs below 0.5 /Wp. The project shall demonstrate the feasibility of the most critical process steps like continuous layer detachment, bonding to a carrier substrate, high-quality epitaxy, handling-free solar cell processing and module integration. As a deliverable, a mini module of higher than 18% efficiency shall be prepared.

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