Light-harvesting discotic liquid crystalline porphyrins and metal complexes

Abstract

Novel discotic liquid crystalline porphyrins and discotic liquid crystalline metal complexes, methods for their preparation, and device fabrication are disclosed. Materials with partially perfluorinated alkyl group in the peripheral chains show a strong tendency towards the formation of homeotropic alignment. These compounds are capable of being used as high-efficiency photovoltaic materials, organic semiconducting materials, and organic light emitting materials.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the molecular structure of one present embodiment compound.

FIG. 2 is the molecular structure of another present embodiment compound.

FIG. 3 is general schematic of a presently conceived photovoltaic cell.

FIGS. 4-9 are molecular structures of specific exemplary compounds.

FIG. 10 is a UV-vis absorption spectrum of one of the exemplary compounds.

FIG. 11 is a fluorescent emission spectrum of the same exemplary compound.

FIG. 12 is a depiction showing crossed polarized optical textures with homeotropic alignment (dark area) of one of the exemplary compounds at room temperature (A and B with different cooling rate).

Claims

1. A liquid crystalline porphyrin or porphyrin metal complex, having the: structure I or II below:

2. A liquid crystalline porphyrin or porphyrin metal complex according to claim 1, wherein at least one of R1, R2, or R3 comprises a perfluoroalkyl group, C60 (fullerene), a C60 derivative, or an aromatic moiety.

3. A liquid crystalline porphyrin or porphyrin metal complex according to claim 1, wherein at least one of R1, R2, or R3 comprises one or more —O—, —S—, —CO—, COO—, —OCO—, —N═N— and/or —C≡C—.

4. A liquid crystalline porphyrin or porphyrin metal complex according to claim 1, wherein said porphyrin can be aligned into an ordered architecture, in which the columns formed by intermolecular π-π stacks are spontaneously perpendicular or parallel on the surface.

5. A liquid crystalline porphyrin or porphyrin metal complex according to claim 4, wherein said ordered architecture is stable within a very wide temperature range and can enhance the charge carrier mobility.

6. A blend comprising the liquid crystalline porphyrin or porphyrin metal complex according to claim 1, further comprising an electron-acceptor material.

7. A blend according to claim 6, wherein said electron-acceptor material comprises a C60 compound, a C60 derivative compound, a dye, and/or a carbon nanotube.

8. A liquid crystalline porphyrin or porphyrin metal complex according to claim 1, wherein said porphyrin or porphyrin metal complex comprises one of the following I, II, or III:

9. A method for producing the porphyrin of claim 1, comprising the following synthesis steps:

10. A method according to claim 9, wherein said synthesis is conducted in an organic solvent.

11. A method according to claim 10, wherein said organic solvent comprises at least one of propionic acid, propionic anhydride, pyrrole, methylene chloride, chloroform, N,N-dimethylformamide, N-methylpyrrolidone, pyridine, triethylamine, ether, tetrahydrofuran, alcohol, ethyl acetate, acetonitrile, ethyl methyl ketone, saturated aliphatic hydrocarbons and aromatic hydrocarbons.

12. A method for producing the porphyrin of claim 1, comprising the following synthesis steps:

13. A method according to claim 12, wherein said synthesis is conducted in an organic solvent.

14. A method according to claim 13, wherein said organic solvent comprises at least one of methylene chloride, chloroform, ether, tetrahydrofuran, pyrrole, propionic acid, propionic anhydride, pyridine, triethylamine, N,N-dimethylformamide, N-methylpyrrolidone, alcohol, ethyl acetate, acetonitrile, ethyl methyl ketone, saturated aliphatic hydrocarbons and aromatic hydrocarbons.

15. A method for producing the porphyrin metal complex of claim 1, comprising the following synthesis steps:

16. A photovoltaic cell including the liquid crystalline porphyrin or porphyrin metal complex of claim 1.

17. A photovoltaic cell according to claim 16, wherein said cell comprises a first transparent electrode, a second electrode, and a photoactive layer positioned between said first and second electrodes comprising the liquid crystalline porphyrin or porphyrin metal complex.

18. A photovoltaic cell according to claim 17, wherein said first electrode is an indium tin oxide electrode, wherein said electrode is coated on a glass or plastic substrate.

19. A photovoltaic cell according to claim 18, wherein said second electrode comprises aluminum, copper, silver and/or gold.

20. A photovoltaic cell according to claim 17, further comprising a photosensitizing agent.

21. A photovoltaic cell according to claim 16, further comprising an electron-acceptor.

22. A photovoltaic cell according to claim 21, wherein said electron-acceptor comprises C60 (fullerene), a C60 derivative, a carbon nanotube or a photosensitive dye.

23. A photo-sensitive electric resistor comprising the liquid crystalline porphyrin or porphyrin metal complex of claim 1.

24. An organic light emitting device comprising the liquid crystalline porphyrin or porphyrin metal complex of claim 1.

25. A method for producing a photovoltaic cell, including the steps of: a) providing a first transparent electrode and a second electrode;b) positioning the liquid crystalline porphyrin or porphyrin metal complex of claim 1 between said first and second electrodes; andc) aligning said porphyrin homeotropically.

26. A method according to claim 25, further comprising: d) sealing the two electrodes together while maintaining a liquid crystal uptake opening between the two;e) heating said porphyrin in a vacuum chamber to melt it;f) placing the cell in said vacuum chamber to remove air from the cell.g) dipping the cell opening into the melted porphyrin; andh) reducing the vacuum level in said vacuum chamber to allow the cell to uptake the melted porphyrin.

27. A bulk heterojunction cell having homeotropically aligned architecture comprising a blend of the liquid crystalline porphyrin or porphyrin metal complex of claim 1 and an electron-acceptor comprising C60, a C60 derivative, a dye and/or a carbon nanotube,

28. A double- or multi-layered photovoltaic cell comprising: i) a donor layer comprising a homeotropically aligned liquid crystalline porphyrin or porphyrin metal complex of claim 1 or a homeotropically aligned blend comprising said liquid crystalline porphyrin or porphyrin metal complex; andii) an acceptor layer comprising a C60 compound, a C60 derivative compound, a dye, and/or a carbon nanotube.