Process for forming an electroactive layer
View Patent ↗There is provided a process for vacuum drying. The process includes the steps of: depositing a liquid composition containing a film-forming material and at least one solvent onto a workpiece to form a wet layer; placing the wet layer on the workpiece into a vacuum chamber including a condenser; and treating the wet layer at a controlled temperature in the range of −25 to 80° C. and under an applied vacuum in the range of 10 −6 to 1,000 Torr for a period of 1-100 minutes; wherein the condenser is maintained at a temperature at which the solvent will condense as a liquid at the applied vacuum.
1. A process for forming a layer of electroactive material, comprising:
providing a workpiece having at least one active area;
depositing a liquid composition comprising the electroactive material in a liquid medium onto the workpiece in the at least one active area, to form a wet layer, wherein the liquid medium comprises at least two liquid components, and at least one component has a boiling point of greater than 100° C.;
placing the wet layer on the workpiece into a vacuum chamber having a condenser therein;
treating the wet layer on the workpiece at a controlled temperature in the range of 30° to 60° C. and at a pressure in the range of 10 −2 to 1 Torr, for a first period of 5-15 minutes, to form a partially dried layer, wherein the condenser is maintained at a temperature at which the at least one component with a boiling point of greater than 100° C. will condense as a liquid at the applied vacuum;
heating the partially dried layer to a temperature above 100° C. for a second period of 1-50 minutes to form a dried layer,
wherein the dried layer has a substantially flat profile in the at least one active area.
2. The process of claim 1 , wherein the dried layer has a thickness variation of less than +/−10% over 90% of the at least one active area.
3. The process of claim 1 , wherein the liquid composition is deposited by a technique selected from the group consisting of ink jet printing and continuous nozzle coating.
4. The process of claim 1 , wherein the workpiece has a multiplicity of active areas.
5. The process of claim 4 , wherein the electroactive material comprises a host material and a photoactive guest material corresponding to a first color, and the liquid composition is deposited in a first portion of the at least one active area.
6. The process of claim 5 , wherein a second liquid composition comprising a second host material and a second photoactive guest material corresponding to a second color is deposited in a second portion of the at least one active area.
7. The process of claim 6 , wherein a third liquid composition comprising a third host material and a third photoactive guest material corresponding to a third color is deposited in a third portion of the at least one active area.
8. The process of claim 1 , wherein the condenser is a surface condenser.
9. The process of claim 1 , wherein the condenser is maintained at a temperature below 20° C.
10. The process of claim 1 , wherein the condenser is maintained at a temperature in the range of −15° to 15° C.
11. The process of claim 1 , wherein the vacuum chamber further comprises means for removing condensed solvent from the chamber.
12. The process of claim 1 , wherein the heating the partially dried layer comprises heating to a temperature of 110° C.-150° C. and the second period is 10-30 min.
13. The process of claim 1 , wherein the electroactive material consists essentially of a hole injection material.
14. The process of claim 1 , wherein the electroactive material consists essentially of a hole transport material.
15. A process for forming a layer of electroactive material, comprising:
providing a workpiece having at least one active area;
depositing an electroactive material in solution with at least one organic solvent onto the workpiece in the the at least one active area, to form a wet layer, wherein, the electroactive material and the at least one organic solvent each has a boiling point of less than 120° C.;
placing the wet layer on the workpiece into a vacuum chamber having a condenser therein;
treating the wet layer on the workpiece at a controlled temperature in the range of −25° to 10° C. at a pressure in the range of 1 Torr to 1,000 Torr, for a first period of 5-25 minutes, to form a partially dried layer, wherein the condenser is maintained at a temperature at which the solvent will condense as a liquid at the applied vacuum;
heating the partially dried layer to a temperature above 100° C. for a second period of 1-50 minutes to form a dried layer,
wherein the dried layer has a substantially flat profile in the at least one active area.
16. The process of claim 15 , wherein the wet layer on the workpiece is treated at a temperature in the range of −10 to 0° C., at a pressure in the range of 10 to 100 Torr, for a time of 5-15 minutes.
17. The process of claim 15 , wherein the dried layer has a thickness variation of less than +/−10% over 90% of the at least one active area.
18. The process of claim 15 , wherein the workpiece has a multiplicity of active areas.