Objective
The overall target of the project is to obtain efficiencies as high as possible by reduction of the mono-crystalline silicon cell thickness. Efficiencies of 20% at 1 sun and 25% for mono-crystalline concentrator cells (under direct beam concentrated light or located into a cavity at 30 W/cm2) are the target figures of MONO-CHESS.
Research is being carried out in order to obtain efficiencies as high as possible by reducing the monocrystalline silicon cell thickness. Efficiencies of 20% at 1 sun and 25% for monocrystalline concentrator cells (under direct beam concentrated light or located into a cavity at 30 W cm{2}) are the target figures of MONO-CHESS. To obtain such cell efficiencies it will be necessary not only to reduce the thickness of the cells in order to increase the open circuit voltage, but also to preserve a high level of light absorption providing optical confinement of the photons.
The following tasks were accomplished:
optimization of textured surfaces and new cell technologies and devices for light confinement;
process development involving techniques for the reduction of recombination and series resistance;
modelling to assess the best structures and the process efforts that must be done first;
measurement of the bonding and cooling of the cells, (in measurements up to 500 suns), spectral response at high injection level and methods of extraction of parameters of the cells;
cell processing which involved combining the preceding successful techniques to obtain high efficiency cells.
These results have achieved an efficiency of 19 to 20% (1 sun) and 24% concentration.
To obtain the mentioned cell efficiencies it will be necessary not only to reduce the thickness of the cells in order to increase the open circuit voltage, but also to preserve a high level of light absorption providing optical confinement of the photons.
According with the above goals, the following tasks must be accomplished as a whole, by the partners:
TASK 1)
OPTICS : Assessment to optimize textured surfaces and new cell technologies and devices for light confinement.
Sub-tasks: 1.1 optical design of cells, 1.2 Texturing development, 1.3 ARC optimization, 1.4 Direct wafer bonding
TASK 2)
PROCESS DEVELOPMENT Includes techniques for the reduction of recombination and series resistance.
Sub-tasks: 2.1 Thinning process development, 2.2 Self-aligned process, 2.3 Surface passivation, 2.4 Reduction of emitter recombination (low Jo)
TASK 3)
MODELLING: To assess the best structures and the process efforts that must be done first.
Sub-tasks: 3.1 Modelling emitter recombination/ structure of cells, 3.2 Modelling base type and doping, 3.3 Series resistance limitations
TASK 4)
MEASUREMENT: It includes the bonding and cooling of the cells, in measurements up to 500 suns, spectral response at high injection level and methods of extraction of parameters of the cells.
Sub-tasks: 4.1 Contact-less measurement and parameter extraction, 4.2 Bonding thin cells to substrata, 4.3 Electrical characterization in wide temperature range under concentrated light
TASK 5)
CELL PROCESSING (FINAL TASK): Combining the preceding successful techniques to obtain high efficiency cells.
Sub-tasks: 5.1 Cell processing at UPM, 5.2 Cell processing at IMEC, 5.3 Cell processing at UCL, 5.4 High efficiency low-cost solar cell processing (Final task)
Funding Scheme
CSC - Cost-sharing contractsCoordinator
28040 Madrid
Spain
Participants (3)
3001 Heverlee
Louvain-la-neuve
13628 Aix-en-provence
