Doped graphene, method of manufacturing the doped graphene, and a device including the doped graphene

1. A composition comprising:

a graphene sheet having a planar structure, wherein the graphene sheet consists of a plurality of carbon atoms covalently bound to each other; and

at least one n-dopant selected from the group consisting of a reduction product of a substituted or unsubstituted nicotinamide; a reduction product of a compound which is chemically bound to a substituted or unsubstituted nicotinamide; and a compound comprising at least two pyridinium moieties in which a nitrogen atom of at least one of the pyridinium moieties is reduced,

wherein the reduction product of the compound which is chemically bound to the substituted or unsubstituted nicotinamide is nicotinamide mononucleotide-H or nicotinamide adenine dinucleotide phosphate-H,

wherein the compound comprising at least two pyridinium moieties in which a nitrogen atom of at least one of the pyridinium moieties is reduced is a viologen,

wherein the composition has a work function which is different than a work function of the graphene sheet.

2. The composition of claim 1 , wherein the viologen is at least one selected from the group consisting of 1,1′-dibenzyl-4,4′-bipyridinium dichloride, methyl viologen dichloride hydrate, ethyl viologen diperchlorate, 1,1′-dioctadecyl-4,4′-bipyridinium dibromide, and di-octyl bis(4-pyridyl)biphenyl viologen.

3. The composition of claim 1 , wherein the viologen has a molecular structure which includes a conjugated bipyridyl structure.

4. The composition of claim 3 , wherein the molecular structure includes at least one group selected from the group consisting of an aryl group, an alkenyl group, and an alkynyl group.

5. The composition of claim 1 , wherein the composition comprises a p-dopant selected from the group consisting of AuCl 3 and dichlorodicyanoquinone.

6. The composition of claim 1 , wherein the composition comprises 1,1′-dibenzyl-4,4′-bipyridinium dichloride.

7. An electrode comprising the composition of claim 1 .

8. The electrode of claim 7 , wherein the electrode is transparent, flexible, or combination thereof.

9. A solar cell comprising the electrode according to claim 7 .

10. A display device comprising the electrode according to claim 7 .

11. The display device of claim 10 , wherein the display device is selected from the group consisting of an organic light emitting display device, an electronic paper display, a liquid crystal device, and a plasma display panel.