Batteries: thermoelectric and photoelectric – Photoelectric – Panel or array
Patent
1998-06-05
2000-05-30
Codd, Bernard
Batteries: thermoelectric and photoelectric
Photoelectric
Panel or array
136244, 136251, 429111, 438 62, 438 66, 438 80, 438 85, 438 97, H01L 27142, H01L 2102, H01M 1036
Patent
active
060693134
DESCRIPTION:
BRIEF SUMMARY
This invention concerns monolithic, series-connected, dye-sensitized photovoltaic modules consisting of dye-sensitized nanoporous semiconductor layers as photoelectrodes on an electrically conducting, transparent substrate, an electron transferring redox electrolyte and counterelectrodes. Single photovoltaic cells of this type have already been described [Journal of the American Chemical Society, vol. 115 (1993) pp. 6382-6390]. Tin oxide coated glass as transparent, electrically conducting substrate is covered with a porous semiconductor layer of nanocrystalline titanium dioxide as photoelectrode and sensitized for visible light by adsorption of a dye. The dye is excited by absorption of light and injects an electron into the titanium dioxide. Through the conducting substrate the electrons reach the external circuit where they may carry out electrical work. The oxidized dye is reduced by the electron transferring electrolyte, which fills the pores of photoelectrode and the space up to the counterelectrode. The counterelectrode usually consists of tin oxide coated glass as well, which is catalytically activated with platinum in order to transfer the electrons arriving from the external circuit back to the electrolyte.
The fabrication of efficient large surface area cells was difficult up to now since the distance between photo- and counterelectrode soon becomes too large (>20 .mu.m) due to the limited flatness of the separate substrates, causing additional ohmic losses and even diffusion limitations of the photocurrent in the electrolyte layer. Moreover the conductivity of the substrate is not sufficient to carry the high photocurrents produced by a large surface area cell. A possible solution would be the series-connection of many narrow stripes of cells to a module, by connecting the counterelectrode of one cell to the photoelectrode of the adjacent cell, as known from amorphous silicon cells [Solar Energy, vol 23 (1979) pp. 145-147]. However, with the present design of the dye-sensitized photovoltaic cell this would require conducting bridges reaching from one substrate through the electrolyte to the other substrate, while the distance between the substrates has to be kept very small (<20 .mu.m). The corrosiveness of the electrolyte leaves little choice of suitable materials for these interconnecting bridges. Also the formation of lines of electrical contacts between the two separate substrates at temperatures which do not destroy the sensitizing dye is difficult to achieve.
In this invention we present a new design of the dye-sensitized solar cell, which allows to fabricate large surface area photovoltaic modules by series-connecting many photo- and counterelectrodes on the same substrate.
To this effect the present invention concerns a battery of photovoltaic cells as specified in claim 1. Particularly useful embodiments of the battery are specified in dependant claims 2 to 13. The invention also concerns a process for manufacturing the battery as specified in claim 14. Particularly useful execution forms of the process are specified in dependant claims 15 to 20.
The FIGURE shows a schematical cross-section of an embodiment of the battery.
The nanoporous photoelectrodes 4 are applied on a transparent conducting substrate 1, as in the original version of the dye-sensitized solar cell [Journal of the American Chemical Society, vol. 115 (1993) pp. 6382-6390], each on a predetermined area of the conducting coating 2. These areas form parallel strips of the required width for each solar cell separated by narrow insulating lines 3, where the conducting coating 2 of the substrate 1 has been removed. The photoelectrodes 4 are applied in such a way that each extends slightly over one edge of the corresponding conducting coating 2, while leaving bare the opposite edge. The photoelectrodes 4 are then covered with a porous layer of an electrical insulator 5. This layer is required to prevent short-circuiting in cases where the material of the counterelectrodes 6 would form ohmic contact with the photoelectro
REFERENCES:
patent: 4097655 (1978-06-01), Witzke
patent: 4754544 (1988-07-01), Hanak
patent: 4968354 (1990-11-01), Nishiura et al.
patent: 5273911 (1993-12-01), Sasaki et al.
patent: 5350644 (1994-09-01), Graetzel et al.
patent: 5593901 (1997-01-01), Oswald et al.
Browning Clifford W.
Codd Bernard
Ecole Polytechnique Federale de Lausanne
LandOfFree
Battery of photovoltaic cells and process for manufacturing same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Battery of photovoltaic cells and process for manufacturing same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Battery of photovoltaic cells and process for manufacturing same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1911720