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Large-grain thin-film crystalline si solar cells on ceramics (LATECS)

Cel

Objectives and problems to be solved:
The consortium, consisting of partners stemming from research and industry, wants to elaborate a cost-effective thin-film crystalline Si solar cell technology, based on thermally assisted Chemical Vapour Deposition (CVD) as deposition technique. The low-cost substrate to be developed further within this project is mullite, a ceramic consisting of Al2O3 and SiO2. The project wants to focus on the realisation of a solar device-worthy thin crystalline Si-film on this substrate by proposing a number of innovative approaches. These approaches avoid the complexity of processes in which zone melting recrystallisation is involved to increase the grain size. These innovative techniques have in common their ability to control and to increase the grain size of the film in which the active layer is produced. A previous European Project (SFINCS: JOR3-CT98-0233) has established the potential of mullite as a low-cost substrate for thin-film crystalline Si solar cells. Cost predictions indicate that its cost can be as low as 30-40 Euro/m2, which is the lowest amongst the substrate candidate materials at the moment. This substrate is also compatible with CVD to realise the active layer. The suitability of this substrate is further evidenced by the relatively high efficiencies obtained in solar cells on mullite (8-9% under AM1.5) in Si-layers recrystallised by Zone Melting Recrystallisation (ZMR), which did not suffer from cracks thanks to the good match between the thermal expansion coefficients of mullite and Si. In order to avoid the complexity of ZMR, this project proposal proposes to control and increase the grain size of the active film by an innovative approach.
Description of the work:
This approach aims at increasing the grain size by deposition of the Si-layer on a dielectric layer with low viscosity. As a result of the enhanced mobility of the Si-adatoms over the surface of this low-viscosity layer (the surface approaches the features of a liquid surface) and the ability of the Si-nuclei to rotate on this surface, large Si-grains can be formed with grain boundaries which take a low-energy configuration. In addition, the dielectricum that is applied through spin coating can act as a barrier or even as a dopant source when P or B is added to the spinning solution. The potential of the approach will be studied by realising a truly monocrystalline Si-film on the mullite substrate (grain size =?) by lift-off and transfer of a porous Si-film onto the mullite substrate, allowing the Si-substrate to be reused several times. This quasi-monocrystalline Si-film will then be thickened by an epitaxial deposition step resulting in a high-quality film, which is processed further into a solar cell. Finally, cells will be realised in the thus obtained Si-layers on mullite using a heterojunction Intrinsic Thin layer emitter approach (HIT) or a classical emitter approach, combined with laser grooving to realise monolithically interconnected modules. In view of the reduction of the grain boundary recombination velocity, cells with an n-type base will be compared to cells with a p-type base.
Expected Results:
This project should result in a thin-film crystalline Si low-cost PV module with a cost/Wp between 1 and 2 Euro/Wp. More specifically, this objective falls apart into the following aspects "Basic study of the proposed approach to avoid ZMR". An efficiency target of 12% on solar cell level is targeted. A module efficiency of 11% is aimed at (module of 10x15 cm2, consisting of 3 connected cells)

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System finansowania

CSC - Cost-sharing contracts

Koordynator

INTERUNIVERSITAIR MIKRO-ELEKTRONICA CENTRUM VZW
Wkład UE
Brak danych
Adres
Kapeldreef 75
3001 HEVERLEE
Belgia

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Uczestnicy (5)