Patent Application
20080002329
a) to 2(e) show preferred chromophores.
One aspect of the present invention is to provide a capacitor with a high power output. A further aspect of the present invention is to provide a capacitor featuring a high dielectric constant sustainable to high frequencies. A still further aspect of the present invention is to provide a capacitor featuring voltage dependent capacitance. In yet another aspect of the present invention, a method to make such a capacitor is provided.
The capacitor, in its simplest form, comprises a first electrode, a second electrode and a chromophore between the first electrode and the second electrode. The chromophore further comprises an electron donor and an electron acceptor separated by a conjugated bridge. The conjugated bridge comprises one or more double bonds that alternate with single bonds in an unsaturated compound. Among the many elements that may be present in the double bond, carbon, nitrogen, oxygen and sulfur are the most preferred. The π electrons in the conjugated bridge are delocalized across the length of the bridge. When a bias is applied across the first and second electrodes, the chromophore becomes more or less polarized with electron density moving from the donor to acceptor or vice versa. When the bias is removed, the original charge distribution is restored. Typically the capacitor comprises a plurality of chromophores.
In one embodiment, a liquid or solid chromophore is placed between the first and second electrodes. A solid chromophore is, for example, pressed into a pellet and placed between the first electrode and the second electrode. The chromophore can be ground into a powder before pressing.
In another embodiment, the chromophore is dissolved or suspended in a polymer. This is termed a “guest-host” system where the chromophore is the guest and the polymer is the host. Polymer hosts include, but are not limited to, poly(methyl methacrylate), polyimides, polycarbonates and poly(ε-caprolactone). These systems are cross-linked or non-cross-linked.
In another embodiment, the chromophore is attached to a polymer. This is termed a “side-chain polymer” system. This system has the advantages over guest-host systems because high chromophore concentrations are incorporated into the polymer without crystallization, phase separation or concentration gradients. Side chain polymers include, but are not limited to, poly[4-(2,2-dicyanovinyl)-N-bis(hydroxyethyl)aniline-alt-(4,4′-methylenebis(phenylisocyanate))]urethane, poly[4-(2,2-dicyanovinyl)-N-bis(hydroxyethyl)aniline-alt-(isophoronediisocyanate)]urethane, poly(9H-carbazole-9-ethyl acrylate), poly(9H-carbazole-9-ethyl methacrylate), poly(Disperse Orange 3 acrylamide), poly(Disperse Orange 3 methacrylamide), poly(Disperse Red 1 acrylate), poly(Disperse Red 13 acrylate), poly(Disperse Red 1 methacrylate), poly(Disperse Red 13 methacrylate), poly[(Disperse Red 19)-alt-(1,4-diphenylmethane urethane)], poly(Disperse Red 19-p-phenylene diacrylate), poly(Disperse Yellow 7 acrylate), poly(Disperse Yellow 7 methacrylate), poly[(methyl methacrylate)-co-(9-H-carbazole-9-ethyl acrylate)], poly[(methyl methacrylate)-co-(9-H-carbazole-9-ethyl methacrylate)], poly[methyl methacrylate-co-(Disperse Orange 3 acrylamide)], poly[methyl methacrylate-co-(Disperse Orange 3 methacrylamide)], poly[(methyl methacrylate)-co-(Disperse Red 1 acrylate)], poly[(methyl methacrylate)-co-(Disperse Red 1 methacrylate)], poly[(methyl methacrylate)-co-(Disperse Red 13 acrylate)], poly[(methyl methacrylate)-co-(Disperse Red 13 methacrylate)], poly[methyl methacrylate-co-(Disperse Yellow 7 acrylate)], poly[methyl methacrylate-co-(Disperse Yellow 7 methacrylate)], poly [[(S)-1-(4-nitrophenyl)-2-pyrrolidinemethyl]acrylate], poly[((S)-(−)-1-(4-nitrophenyl)-2-pyrrolidinemethyl)acrylate-co-methyl methacrylate], poly [[(S)-1-(4-nitrophenyl)-2-pyrrolidinemethyl]methacrylate] and poly[((S)-(−)-1-(4-nitrophenyl)-2-pyrrolidinemethyl)methacrylate-co-methyl methacrylate]. These systems are cross-linked or non-cross-linked.
In another embodiment, the chromophore is incorporated into the polymer backbone. These systems are termed “main-chain polymer” systems. Main-chain polymers include, but are not limited to, 4-methoxy-4′-carbomethoxy-α-amino-α′-cyanostilbenes, the AB copolymer of α-cyano-m-methoxy-p-(ω-oxypropoxy)cinnamate with ω-hydroxydodecanoate, poly[(4-N-ethylene-N-ethylamino)-α-cyanocinnamate, bispheno A-4-amino-4′-nitrotolan, bisphenol A-4-nitroaniline and bisphenol A-N,N-dimethyl-4-nitro-1,2-phenylenediamine. These systems are cross-linked or non-cross-linked.
In another embodiment, the chromophore is embedded in matrices such as oxides, halides, salts and organic glasses. An example of a matrix is inorganic glasses comprising the oxides of aluminum, boron, silicon, titanium, vanadium and zirconium.
The chromophore is aligned, partially aligned or unaligned. The chromophore is preferably aligned as this results in higher capacitance values in the capacitor. The preferred method of alignment is to apply a dc electric field to the chromophore at a temperature at which the chromophore can be oriented. This method is termed “poling.” Poling is generally performed near the glass transition temperature of polymeric and glassy systems. A preferred method of poling is corona poling.
A preferred capacitor further comprises a first insulator between the first electrode and the chromophore and a second insulator between the second electrode and the chromophore. First and second insulators include, but are not limited to, organic, organometallic and inorganic insulators. Examples of insulators include metal oxides, non-metal oxides, metal hydroxides, non-metal hydroxides, metal halides, non-metal halides, metal hydrides, non-metal hydrides, self-assembled monolayers, plastics and polymers such as poly(ethylene oxide), poly(propylene oxide) and poly(vinylidene fluoride). The first and second insulators prevent or decrease tunneling between the first and second electrodes and the chromophore. In one embodiment, an insulating self-assembled monolayer is attached to an electrode. An example is octadecanethiol attached to a gold electrode with a Au(111) surface. In another embodiment, the chromophore is attached to the insulator which is attached to the electrode.
Preferred electron donors include, but are not limited to, amino and phosphino groups and combinations thereof. Preferred electron acceptors include, but are not limited to, nitro, carbonyl, oxo, thioxo, sulfonyl, malononitrile, isoxazolone, cyano, dicyano, tricyano, tetracycano, nitrile, dicarbonitrile, tricarbonitrile, thioxodihydropyrimidinedione groups and combinations thereof. More conjugated bridges include, but are not limited to, 1,2-diphenylethene, 1,2-diphenyldiazene, styrene, hexa-1,3,5-trienylbenzene and 1,4-di(thiophen-2-yl)buta-1,3-diene, alkenes, dienes, trienes, polyenes, diazenes and combinations thereof.
The first and second electrodes are selected from the group consisting of conductors and semiconductors. Conductors include, but are not limited to, metals, conducting polymers and graphite including graphene sheets. Semiconductors include, but are not limited to, silicon, germanium, silicon carbide, gallium arsenide and selenium. Preferred electrodes are copper, silver, gold, aluminum, titanium, palladium, platinum, nickel, zinc, tin, silicon and gallium arsenide. In one preferred embodiment, the electrode surface is Au(111). A Au(111) surface is preferably obtained from the evaporation of a thin gold film onto a flat support. Flat supports include, but are not limited to, glass, plastic, silicon and metal surfaces.
a) to (l) illustrate preferred chromophores: N,N-dimethyl-4-(4-nitrostyryl)aniline (a), 4-(4-(dimethylamino)styryl)benzaldehyde (b), 4-((4-nitrophenyl)diazenyl)-N-phenylaniline (c), dodeca-2,4,6,8,10-pentaene (d), N,N-diallyl-4-(4-(methylsulfonyl)styryl)aniline (e), 2-(4-(diethylamino)benzylidene)malononitrile (f), 4-(5-(4-(dimethylamino)phenyl)penta-2,4-dienylidene)-3-phenylisoxazol-5-one (g), 2-(5-(4-(5-(piperidin-1-yl)thiophen-2-yl)buta-1,3-dienyl)thiophen-2-yl)ethene-1,1,2-tricarbonitrile (h), dicyano(4-(1-cyano-3-(diethyliminio)prop-1-enyl)phenyl)methanide (i), 5-(5-(4-(dimethylamino)phenyl)penta-2,4-dienylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6-dione (j), 4-((4-nitrophenyl)diazenyl)-N,N-diphenylaniline (k) and unknown name (l). Other preferred chromophores include (2,6-Dimethyl-4H-pyran-4-ylidene)malononitrile, (S)-(−)-1-(4-Nitrophenyl)-2-pyrrolidinemethanol, [4-[Bis(2-hydroxyethyl)amino]phenyl]-1,1,2-ethylenetricarbonitrile, 1-Docosyl-4-(4-hydroxystyryl)pyridinium bromide, 2-(Dimethylamino)vinyl-1-nitronaphthalene, 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane, 4-[4-(Dimethylamino)styryl]-1-methylpyridinium p-toluenesulfonate, 2-[[5-(Dibutylamino)-2-thienyl]methylene]-1H-indene-1,3(2H)-di one, 2-[4-((4-(Bis(2-hydroxyethyl)amino]phenyl)(cyano)methylene]-2,5-cyclohexadien-1-ylidene]malonitrile, 2-[4-(Dimethylamino)styryl]pyridine, 2-[Ethyl[4-[2-(4-nitrophenyl)ethenyl]phenyl]amino]ethanol, 2-Amino-3-nitropyridine, 2-Amino-5-nitropyridine, 2-Aminofluorene, 2-Chloro-3,5-dinitropyridine, 2-Chloro-4-nitroaniline, 2-Methyl-4-nitroaniline, 2-Nitroaniline, 3-[(4-Nitrophenyl)azo]-9H-carbazole-9-ethanol, 3-Methyl-4-nitropyridine N-oxide, 3-Nitroaniline, 4-(Dibenzylamino)benzaldehyde-N,N-diphenylhydrazone, 4-[4-(Dimethylamino)styryl]-1-docosylpyridinium bromide, 4-[4-(Dimethylamino)styryl]pyridine, 4-Dimethylamino-4′-nitrostilbene, 4-Nitroaniline, 5-Nitroindole, 5-Nitrouracil, 7,7,8,8-Tetracyanoquinodimethane, 9-Ethyl-3-carbazolecarboxaldehyde-N-methyl-N-phenylhydrazone, Disperse Orange 25, Disperse Orange 3, Disperse Red 1, Disperse Red 13, Disperse Red 19, Disperse yellow 7, Ethyl 4-(dimethylamino)benzoate, Gentian Violet, N-(2,4-Dinitrophenyl)-L-alanine methyl ester, N,N-Dimethyl-N′-[(5-nitro-2-thienyl)methylene]-1,4-phenylenediamine, N-[3-Cyano-3-[4-(dicyanomethyl)phenyl]-2-propenylidene]-N-ethyl-ethaniminium inner salt, Nile Blue A, N-Methyl-4-nitroaniline, trans-4-[4-(Dimethylamino)styryl]-1-methylpyridinium iodide and trans-4-[4-(Dimethylamino)styryl]-1-methylpyridinium p-toluenesulfonate.
In one embodiment, the chromophore comprises more than one electron donor-conjugated bridge-electron acceptor combination in series. In another embodiment, the chromophore comprises more than one electron donor-conjugated bridge-electron acceptor combination in parallel. In yet another embodiment, the chromophore comprises electron donor-conjugated bridge-electron acceptor combinations both in parallel and in series.
