Enhancing performance characteristics of organic semiconducting films by improved solution processing

1. A method of forming an organic semiconductor film, comprising the steps of adding an amount of one or more low molecular weight alkyl-containing molecules to a solution of a conjugated polymer serving as an electron donor or electron acceptor, and forming the organic semiconductor film from the solution, wherein the one or more low molecular weight alkyl-containing molecules are selected from C 4 -C 20 alkanes, C 4 -C 16 alcohols, and C 4 -C 16 alkyl thiols;

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 low molecular weight alkyl-containing molecules are selected from C 4 -C 20 alkanes.

3. The method of claim 1 , wherein the low molecular weight alkyl-containing molecules are selected from C 4 -C 16 alcohols.

4. The method of claim 1 , wherein the low molecular weight alkyl-containing molecules are selected from C 4 -C 16 alkyl thiols.

5. The method of claim 1 , wherein the forming of the conjugated polymer film from the solution is performed by spin-casting.

6. The method of claim 1 , wherein the one or more low molecular weight alkyl-containing 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.

7. The method of claim 1 , wherein the organic semiconductor film comprises a conjugated polymer film electron donor and an organic electron acceptor.

8. The method of claim 7 , wherein the conjugated polymer film electron donor and organic electron acceptor form a bulk heterojunction.

9. The method of claim 7 , 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.

10. The method of claim 7 , wherein the organic electron acceptor comprises a fullerene derivative.

11. The method of claim 10 , 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.

12. The method of claim 1 , wherein the fullerene derivative is selected from C61-PCBM or C71-PCBM.

13. The method of claim 1 , wherein the solution comprises a solvent selected from chlorobenzene, dichlorobenzene, trichlorobenzene, benzene, toluene, chloroform, dichloromethane, dichloroethane, xylenes, α,α,α-trichlorotoluene, methyl naphthalene, chloronaphthalene, or mixtures thereof.