Liquid compositions for inkjet printing of organic layers or other uses

1. A method of forming an organic layer for an organic electronic device, comprising:

having a liquid composition comprising a small molecule organic semiconductor material mixed in a solvent preparation, the solvent preparation comprising a solvent and 0.1 wt % or less of impurities having a higher boiling point than the solvent, the solvent having a boiling point of 200° C. or higher at 1 atm; and

depositing the liquid composition on a surface.

2. The method of claim 1 , wherein the solvent preparation is a purified solvent preparation, and wherein providing the liquid composition comprises:

having a crude solvent preparation comprising the solvent and more than 0.1 wt % of impurities having a higher boiling point than the solvent;

purifying the crude solvent preparation by removing at least some of the impurities having a higher boiling point than the solvent to obtain the purified solvent preparation; and

mixing the small molecule organic semiconductor material with the purified solvent preparation.

3. The method of claim 1 , wherein purifying the crude solvent preparation comprises distilling the crude solvent preparation.

4. The method of claim 1 , wherein the solvent has a boiling point of 250° C. or higher.

5. The method of claim 1 , wherein the solvent is 3-phenoxytoluene solvent.

6. The method of claim 1 , wherein the solvent is 1-tetralone.

7. The method of claim 1 , wherein the impurities having a higher boiling point than the solvent is essentially non-detectable by ultraviolet detection-high pressure liquid chromatography.

8. The method of claim 1 , wherein the concentration of the organic semiconductor material is in the range of 0.01-2 wt %.

9. The method of claim 1 , wherein the organic semiconductor material is an organometallic complex of a transition metal.

10. A method of making an organic light emitting device having an anode, a cathode, and an organic layer disposed between the anode and the cathode, wherein the organic layer is formed by the method of claim 1 .

11. The method of claim 10 , wherein:

the organic layer is formed by the method of claim 2 , the organic layer being an emissive layer; and

the organic light emitting device has a T 80 lifetime at least 1.5 times longer than a comparative device that is made identically except that the emissive layer is made using the crude solvent preparation.

12. The method of claim 10 , wherein the step of depositing is performed by inkjet printing.

13. A liquid composition comprising:

a solvent having a boiling point of 200° C. or higher at 1 atm; and

a small molecule organic semiconductor material mixed in the solvent at a concentration in the range of 0.01-10 wt %;

wherein the liquid composition has 0.1 wt % or less of impurities having a higher boiling point than the solvent.

14. The liquid composition of claim 13 , wherein the concentration of the organic semiconductor material is in the range of 0.01-2 wt %.

15. The liquid composition of claim 13 , wherein the organic semiconductor material is an emissive phosphorescent compound.

16. The liquid composition of claim 15 , wherein the emissive phosphorescent compound is an organometallic complex of a transition metal.

17. The liquid composition of claim 15 , wherein the liquid composition further comprises a host compound for the phosphorescent compound.

18. The liquid composition of claim 17 , wherein the host compound is a carbazole-containing compound.

19. The liquid composition of claim 13 , wherein the solvent has a boiling point of 250° C. or higher.

20. The liquid composition of claim 13 , wherein the solvent is 3-phenoxytoluene.

21. The liquid composition of claim 13 , wherein the solvent is 1-tetralone.