An improved vertical junction back-contact silicon solar cell (BCVJ cell) has been developed showing good performance under 1 sun and under concentrated light. The cell is provided with a pass-through holes matrix that acts as vertical electrodes. The holes are alternately p- and n-doped in order to form radial p-n vertical junctions. The front surface is metal-free and it prevents the shadowing of the incident light. The distance between the vertical electrodes is 50 μm, much lower than the substrate thickness. This feature allows a reduction of the cell series resistance and an increase of the collection efficiency of red-photons also by using thick substrates with low lifetime. The measured efficiency is of 22% at 80 suns and higher than 19% up to 200 Suns. The cell performance were compared with the one of a conventional solar cell with a front n-p planar junction, which is fabricated on the same silicon substrate by means of a similar process. The back-contact vertical junction cell shows an increment of 18% in the JSC with respect to the conventional cell. The increase is due to the front shadow elimination and to the high collection efficiency of red and infra-red photons, as demonstrated by means of the experimental IQE.
BACK-CONTACT VERTICAL JUNCTION SILICON SOLAR CELLS FOR CONCENTRATING PHOTOVOLTAICS
Paternoster, Giovanni;Bellutti, Pierluigi;Collini, Amos;Ferrario, Lorenza;Ficorella, Francesco;Mattedi, Francesca
2013-01-01
Abstract
An improved vertical junction back-contact silicon solar cell (BCVJ cell) has been developed showing good performance under 1 sun and under concentrated light. The cell is provided with a pass-through holes matrix that acts as vertical electrodes. The holes are alternately p- and n-doped in order to form radial p-n vertical junctions. The front surface is metal-free and it prevents the shadowing of the incident light. The distance between the vertical electrodes is 50 μm, much lower than the substrate thickness. This feature allows a reduction of the cell series resistance and an increase of the collection efficiency of red-photons also by using thick substrates with low lifetime. The measured efficiency is of 22% at 80 suns and higher than 19% up to 200 Suns. The cell performance were compared with the one of a conventional solar cell with a front n-p planar junction, which is fabricated on the same silicon substrate by means of a similar process. The back-contact vertical junction cell shows an increment of 18% in the JSC with respect to the conventional cell. The increase is due to the front shadow elimination and to the high collection efficiency of red and infra-red photons, as demonstrated by means of the experimental IQE.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
