Batteries: thermoelectric and photoelectric – Photoelectric – Cells
Reexamination Certificate
2001-05-25
2004-03-02
Diamond, Alan (Department: 1753)
Batteries: thermoelectric and photoelectric
Photoelectric
Cells
C136S258000, C136S256000, C257S043000, C257S040000, C257S053000, C257S431000, C438S085000, C438S096000, C438S082000, C564S434000, C429S111000
Reexamination Certificate
active
06700058
ABSTRACT:
The present invention is related to a photoelectric device, hole transporting agents, uses and mixtures thereof, solar cells comprising the same and methods for the manufacture of photoelectric conversion devices.
Since the demonstration of crystalline silicon p
junction solar cell in 1954 by Chapin et al. with a reported efficiency of 6%, there was a dramatic increase in the efficencies of such cells as a result of improvements in current, significant increase in voltage and splitting the sunlight among solar cells of differing band gaps. The higher voltages resulted directly from increasing the densities of minority carriers generated by absorbed sunlight. By reducing the minority carrier recombination rate, trapping light in active layers and by increasing the intensity of light with concentration optics, efficiencies as high as 25-30% have been reported for two band-gap single crystal laboratory cells like AlGaAs/GaAs. Thin film multijunction, multi-band-gap cells using hydrogenated amorphous silicon (a-Si:H) or polycrystalline alloys exhibit up to 15% laboratory efficiency. The efficiencies of commercial power systems in the field remain in the range of 3 to 12%.
As an alternative a dye sensitized semiconductor-electrolyte solar cell was developed by Grätzel et al. consisting of titanium dioxide nanoparticles with a ruthenium complex adsorbed on the surface an iodine-iodide electrolyte as disclosed in WO 91/16719. The ruthenium complex acts a as sensitizer, which absorbs light and injects an electron into titanium dioxide; the dye is then regenerated by electron transfer from the iodine-iodide redox couple. The advantage of such a solar cell results from the fact that no crystalline semiconductors have to be used anymore while already providing conversion efficiencies of light into electrical energy of up to 12% (O'Regan, B. et al; Nature (1991), 353, p. 737).
The iodine-iodide redox system imposes several limitations to the dye sensitized semiconductor-electrolyte solar cell such as offensiveness of these compounds and limitations in adapting the system's energy levels to the one of the dye. WO 98/48433 discloses the use of a hole transporting material as the redox system in such a solar cell. The hole transporting materials disclosed are spiro fluorene compounds which are dissolved in some electrolytic solution. The same type of compounds for use as hole transporting material is disclosed in Bach et al. (Bach et al.; Nature (1998), 395, p.583-585).
EP 0 901 175 A2 discloses the use of other organic hole transporting materials such as aromatic tertiary amine compounds. The application of the organic hole transporting material can be performed by vacuum evaporation or by coating using a coating solution. The selection of the solvent used for the preparation of the coating solution focuses on a combination of low viscosity and low vapor pressure which requires a compromise. Additionally, the solvent has to exhibit a distinct anodic boundary potential.
The problem underlying the present invention is to provide for a photoelectric conversion device comprising a nanoparticulate semiconductor which may be sensitized with a dye, and an organic hole transporting agent whereby the organic hole material is in intimate contact with the semiconductor or—if present—with the dye. In another aspect the underlying problem is related to a photoelectric conversion device comprising a nanoparticulate semiconductor which may be sensitized with a dye, and an organic hole transporting agent which exhibits a higher photo-to-electron conversion efficiency and light-to-electric energy conversion efficiency than the respective devices known in the prior art.
A further object of the present invention is to provide compounds which can be used as hole transporting materials in photoelectric conversion devices.
A still further objective of the present invention is to provide a method for the manufacture of a photoelectric device, more particularly of photoelectric device exhibiting the favorable characteristics as defined above.
This problem is solved in a first aspect by a photoelectric conversion device comprising
a semiconductor and
an organic electrically conducting agent,
wherein said organic electrically conducting agent exhibits a melting temperature Tm which is lower than the operation temperature of the photoelectric conversion device.
This problem is solved in a second aspect by a photoelectric conversion device comprising
a semiconductor and
an organic electrically conducting agent,
wherein the melting temperature Tm of the organic electrically electrically conducting agent is about 140° C. or less.
This problem is furthermore solved in a third aspect by a photoelectric conversion device comprising
a semiconductor and
an organic electrically conducting agent,
wherein the organic electrically conducting agent is present in a solid but non-crystalline form.
This problem is finally solved in a fourth aspect by a photoelectric conversion device comprising
a semiconductor and
an organic electrically conducting agent,
wherein said organic electrically conducting agent exhibits a glass-transition temperature T
g
of about 60° C. or less.
In a preferred embodiment of the inventive photoelectric conversion device wherein the organic electrically conducting agent is present in a solid but non-crystalline form; the organic electrically conducting agent is present in an amorphous form. In an alternative embodiment, the glass transition temperature Tg of the organic electrically conducting agent is at or below the operation temperature range of the photoelectric device.
In a preferred embodiment of the inventive device according to any of the various above aspects the electrically conducting agent exhibits a glass-transition temperature T
g
of about 60° C. or less.
In a preferred embodiment of the photoelectric devices according to any of the aspects described above said organic electrically conducting agent exhibits a glass-transition temperature T
g
of about 40° C. or less, preferably of about 30° C. or less and more preferably of about 20° C. or less.
In an even more preferred embodiment of the inventive photoelectric devices said organic electrically conducting agent exhibits a glass-transition temperature T
g
of about 10° C. or less and preferably of about 0° C. or less.
In a further embodiment of the photoelectric devices according to above aspects said organic electrically conducting agent comprises at least one organic compound.
In another preferred embodiment of the photoelectric device the semiconductor is sensitized with a dye.
In a preferred embodiment of the inventive photoelectric devices said organic electrically conducting agent comprises a mixture of at least two organic compounds.
In another embodiment of the inventive photoelectric devices said organic electrically conducting agent further comprises at least one dopant.
In an embodiment of the inventive photoelectric devices said organic electrically conducting agent is a hole transporting agent.
In a further embodiment the inventive photoelectric devices said dye is a ruthenium complex.
In still a further embodiment of the inventive photoelectric devices said semiconductor is porous.
In a preferred embodiment said semiconductor comprises nanoparticles, preferably nanoparticles of TiO
2
.
The problem is also solved by a compound acting as a hole transporting agent which is a triphenyldiamine derivative represented by formula (I)
wherein Ar is a substituent represented by formula (II)
The problem is also solved by a compound acting as a hole transporting agent which is a triphenyldiamine derivative represented by formula (III)
wherein Ar is a substituent represented by formula (IV)
In a further aspect the problem is solved by the use of the inventive compounds, i.e. the compound as represented by formulae (I) and (II) or a compound as represented by formulae (III) and (IV) in the inventive devices, more particularly as the organic electrically conducting agent.
In still a further aspect the problem is solved by a m
Karickal Haridas R.
Lupo Donal
Mukundan Thelakkat
Nelles Gabriele
Schmidt Hans-Werner
Diamond Alan
Frommer William S.
Frommer & Lawrence & Haug LLP
Megerditchian Samuel H.
Sony International (Europe) GmbH
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