Functionalization of a substrate

1. A method of increasing a work function of a surface of an electrode, the method comprising:

obtaining an electronegative species from a precursor using electromagnetic radiation; and

reacting the surface of the electrode with the electronegative species to bond the electronegative species to the surface.

2. The method of claim 1 wherein the electronegative species is a halogen.

3. The method of claim 1 wherein the electromagnetic radiation has a wavelength of at least 100 nm.

4. The method of claim 1 wherein the electromagnetic radiation has a wavelength of less than 400 nm.

5. The method of claim 1 further comprising cleaning the surface of the electrode prior to reacting the surface of the electrode with the electronegative species.

6. The method of claim 1 wherein the electrode is a transparent conducting oxide.

7. The method of claim 6 wherein the transparent conducting oxide is ITO.

8. The method of claim 1 wherein the electronegative species is selected to obtain an electrode of a predetermined work function.

9. The method of claim 1 wherein surface coverage of the species is selected to obtain an electrode of a predetermined work function.

10. The method of claim 2 wherein up to about a monolayer of halogen is functionalized to the substrate.

11. The method of claim 10 wherein the halogen is chlorine.

12. The method of claim 1 wherein the precursor is a volatile liquid.

13. The method of claim 1 wherein the precursor is a gas.

14. The method of claim 1 wherein the substrate is functionalized to increase its stability in air.

15. An electrode made by the method of claim 1 comprising a surface functionalized with an electronegative species.

16. An organic electronic device comprising the electrode of claim 15 .

17. A system for chemically functionalizing a substrate with an electronegative species, the system comprising:

a reaction chamber operable to receive a precursor containing the electronegative species, and the substrate;

a radiation emitter operable to emit electromagnetic radiation into the reaction chamber to generate the electronegative species from the precursor, and wherein the electronegative species chemically bond with the substrate.

18. The system of claim 17 wherein the radiation emitter is operable to emit radiation having a wavelength of between 100 nm and 400 nm.

19. The system of claim 17 wherein the radiation emitter is external to the reaction chamber and the reaction chamber is operable to receive ultraviolet radiation from the radiation emitter.

20. A method of increasing a work function of a surface of an electrode, the method comprising:

obtaining chlorine from a precursor using a plasma; and

reacting the surface of the electrode with the chlorine to form at least about 20% of a chlorine monolayer on the surface.

21. The method of claim 20 wherein up to about a monolayer of chlorine is reacted to the surface of the electrode.

22. The method of claim 20 wherein the substrate comprises a transparent conducting oxide.

23. The method of claim 22 wherein the transparent conducting oxide is ITO.

24. The method of claim 21 wherein the surface coverage of the chlorine is selected to obtain an electrode of a predetermined work function.

25. An electrode having a surface functionalized with at least about 20% of a monolayer of halogen.

26. An organic electronic device comprising the electrode of claim 25 .

27. The organic electronic device of claim 16 comprising an organic light emitting diode.

28. The method of claim 10 wherein the surface is functionalized with at least about 20% of a monolayer of halogen.

29. The method of claim 1 wherein the electromagnetic radiation has a wavelength corresponding to the ultraviolet region of the electromagnetic spectrum.

30. The electrode of claim 15 wherein the surface is functionalized with at least about 20% of a monolayer of halogen.