Enhancing performance characteristics of organic semiconducting films by improved solution processing
View Patent ↗Improved processing methods for enhanced properties of conjugated polymer films are disclosed, as well as the enhanced conjugated polymer films produced thereby. Addition of low molecular weight alkyl-containing molecules to solutions used to form conjugated polymer films leads to improved photoconductivity and improvements in other electronic properties. The enhanced conjugated polymer films can be used in a variety of electronic devices, such as solar cells and photodiodes.
1. A method of forming an organic semiconductor film, comprising the steps of adding an amount of one or more low molecular weight molecules to a solution of one or more organic semiconductors, and forming the organic semiconductor film from the solution, wherein the low molecular weight molecules are selected from the group consisting of C 4 -C 20 alkanes substituted with one or more substituents selected from aldehyde, dioxo, hydroxy, thiol, thioalkyl, amine, amide, thioether, and epoxide groups, with the proviso that if a thiol or hydroxy group substituent is present, at least one independently chosen additional substituent must also be present;
wherein the organic semiconductor film comprises a conjugated polymer film electron donor and an organic electron acceptor, or the organic semiconductor film comprises a conjugated polymer film electron acceptor and an organic electron donor.
2. The method of claim 1 , wherein the organic semiconductor film comprises a conjugated polymer film.
3. The method of claim 2 , wherein the forming of the conjugated polymer film from the solution is performed by spin-casting.
4. The method of claim 1 , wherein the low molecular weight molecules are selected from C 4 -C 20 alkanes substituted with at least one hydroxy group and at least one thiol group.
5. The method of claim 4 , wherein the one or more low molecular weight molecules are selected from dithioalkanes.
6. The method of claim 5 , wherein the dithioalkanes are alpha, omega-substituted.
7. The method of claim 6 , wherein the one or more low molecular weight molecules selected from alpha, omega-substituted dithioalkanes are selected from the group consisting of 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, and 1,9-nonanedithiol.
8. The method of claim 1 , wherein the one or more low molecular weight molecules is present in the solution used to form the conjugated polymer film in an amount of about 0.1% to about 10% v/v.
9. The method of claim 1 , wherein the organic semiconductor film comprises a conjugated polymer film electron donor and an organic electron acceptor.
10. The method of claim 9 , wherein the conjugated polymer film electron donor and organic electron acceptor form a bulk heterojunction.
11. The method of claim 9 , wherein the conjugated polymer film electron donor comprises a polymer selected from polyacetylene, a polyphenylene, poly(3-alkylthiophenes) where alkyl is from 6 to 16 carbons (P3AT′s), poly-(3 -hexylthiophene) (P3HT), poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT), polyphenylacetylene, polydiphenylacetylene, polyanilines, poly(p-phenylene vinylene) (PPV) and alkoxy derivatives thereof, poly(2-methoxy,5-(2′-ethyl-hexyloxy)-p-phenylenevinylene) (MEH-PPV), poly(2,5-dimethoxy-p-phenylene vinylene) (PDMPV), a polythiophene, a poly(thienylenevinylene), poly(2,5-thienylenevinylene), a polyporphyrin, a porphyrinic macrocycle, a thiol-derivatized polyporphyrin, a polymetallocene, a polyferrocene, a polyphthalocyanine, a polyvinylene, a polyphenylvinylene, a polysilane, a polyisothianaphthalene, or a polythienylvinylene, or a derivative of one or more of the foregoing materials, or a blend or combination of two or more of the foregoing materials in any proportion.
12. The method of claim 9 , wherein the organic electron acceptor comprises a fullerene derivative.
13. The method of claim 12 , wherein the fullerene derivative is selected from compounds of the formula:
where “fullerene” is independently selected from a C 60 , C 70 , or C 84 fullerene moiety,
Ar is independently phenyl or thienyl, which can be unsubstituted or substituted,
R 1 is independently C 1 -C 12 alkyl, and
R 2 is independently —O—C 1 -C 12 alkyl or —O—C 1 -C 12 alkyl-SH.
14. The method of claim 13 , wherein the fullerene derivative is selected from C61-PCBM or C71-PCBM.
15. The method of claim 1 , wherein the solvent used in the solution is chlorobenzene, dichlorobenzene, trichlorobenzene, benzene, toluene, chloroform, dichloromethane, dichloroethane, xylenes, α,α,α-trichlorotoluene, methyl naphthalene, chloronaphthalene, or mixtures thereof.
16. A method of forming an organic semiconductor film, comprising the steps of adding an amount of one or more low molecular weight molecules to a solution of one or more organic semiconductors, and forming the organic semiconductor film from the solution, wherein the low molecular weight molecules are selected from the group consisting of C 4 -C 20 alkanes substituted with at least two substituents selected from aldehyde, dioxo, hydroxy, thiol, thioalkyl, amine, amide, thioether, and epoxide groups.
17. The method of claim 16 , wherein the organic semiconductor film comprises a conjugated polymer film.
18. The method of claim 17 , wherein the forming of the conjugated polymer film from the solution is performed by spin-casting.
19. The method of claim 16 , wherein the low molecular weight molecules are selected from C 4 -C 20 alkanes substituted with at least one hydroxy group and at least one thiol group.
20. The method of claim 19 , wherein the one or more low molecular weight molecules are selected from dithioalkanes.
21. The method of claim 20 , wherein the dithioalkanes are alpha, omega-substituted.
22. The method of claim 21 , wherein the one or more low molecular weight molecules selected from alpha, omega-substituted dithioalkanes are selected from the group consisting of 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, and 1,9-nonanedithiol.
23. The method of claim 16 , wherein the one or more low molecular weight molecules is present in the solution used to form the conjugated polymer film in an amount of about 0.1% to about 10% v/v.
24. The method of claim 16 , wherein the organic semiconductor film comprises a conjugated polymer film electron donor and an organic electron acceptor.
25. The method of claim 24 , wherein the conjugated polymer film electron donor and organic electron acceptor form a bulk heterojunction.
26. The method of claim 24 , wherein the conjugated polymer film electron donor comprises a polymer selected from polyacetylene, a polyphenylene, poly(3-alkylthiophenes) where alkyl is from 6 to 16 carbons (P3AT's), poly-(3-hexylthiophene) (P3HT), poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole) ] (PCPDTBT), polyphenylacetylene, polydiphenylacetylene, polyanilines, poly(p-phenylene vinylene) (PPV) and alkoxy derivatives thereof, poly(2-methoxy,5-(2′-ethyl-hexyloxy)-p-phenylenevinylene) (MEH-PPV), poly(2,5-dimethoxy-p-phenylene vinylene) (PDMPV), a polythiophene, a poly(thienylenevinylene), poly(2,5-thienylenevinylene), a polyporphyrin, a porphyrinic macrocycle, a thiol-derivatized polyporphyrin, a polymetallocene, a polyferrocene, a polyphthalocyanine, a polyvinylene, a polyphenylvinylene, a polysilane, a polyisothianaphthalene, or a polythienylvinylene, or a derivative of one or more of the foregoing materials, or a blend or combination of two or more of the foregoing materials in any proportion.
27. The method of claim 24 , wherein the organic electron acceptor comprises a fullerene derivative.
28. The method of claim 27 , wherein the fullerene derivative is selected from compounds of the formula:
where “fullerene” is independently selected from a C 60 , C 70 , or C 84 fullerene moiety,
Ar is independently phenyl or thienyl, which can be unsubstituted or substituted,
R 1 is independently C 1 -C 12 alkyl, and
R 2 is independently —O—C 1 -C 12 alkyl or —O—C 1 -C 12 alkyl-SH.
29. The method of claim 28 , wherein the fullerene derivative is selected from C61-PCBM or C71-PCBM.
30. The method of claim 16 , wherein the solvent used in the solution is chlorobenzene, dichlorobenzene, trichlorobenzene, benzene, toluene, chloroform, dichloromethane, dichloroethane, xylenes, α,α,α-trichlorotoluene, methyl naphthalene, chloronaphthalene, or mixtures thereof.