Patterned deposition of a material

• US 6,221,438 B1
• Filed: 02/16/1999
• Issued: 04/24/2001
• Est. Priority Date: 11/03/1998
• Status: Expired due to Term

• Current Assignee: MEC Management, LLC (Three Affiliated Tribes of the Fort Berthold Reservation, North Dakota)
• Original Assignee: Sarnoff Corporation (SRI International, Inc.)
• Inventors: Matthies, Dennis Lee
• Primary Examiner(s): Beck, Shrive
• Assistant Examiner(s): BARR, MICHAEL E
• Application Number:
  US09/250,328
• Time in Patent Office: 798 Days
• Field of Search: 427/458, 427/466, 427/469, 427/470, 427/472, 427/474, 427/475, 427/66, 427/67, 427/68, 427/71, 427/197, 427/202, 427/203, 427/258, 427/335, 427/337, 427/377, 427/372.2, 427/402, 361/226, 361/227, 361/228
• US Class Current: 427/466
• CPC Class Codes: B05D 1/06 Applying particulate materials
• CPC Class Codes: H10K 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
• CPC Class Codes: H10K 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass
• CPC Class Codes: H10K 71/13 using printing techniques, e.g. ink-jet printing or screen printing
• CPC Class Codes: H10K 71/18 using non-liquid printing techniques, e.g. thermal transfer printing from a donor sheet

Abstract

A display structure is formed using patterned deposition of display materials. A substrate includes a plurality of distinct electrodes. A plurality of droplets including a material are formed and charged to a second polarity. First selected ones of the plurality of electrodes are charged to a first polarity opposite the second polarity to selectively attract the droplets including the material to the oppositely charged first selected ones of the plurality of electrodes.

Claims

1. A method for depositing display material onto a display structure comprising the steps of:

(a) providing a first substrate having a plurality of distinct electrodes;

(b) forming a plurality of liquid droplets including portions of the display material charged to a first polarity; and

(c) selectively attracting the plurality of liquid droplets toward first selected electrodes of the plurality of distinct electrodes to selectively deposit the plurality of portions of the display material directly on the first selected electrodes to be in electrical contact with the first selected electrodes.

2. The method of deposition according to claim 1 wherein step (c) includes charging the first selected electrodes to a second polarity opposite the first polarity.

3. The method of deposition according to claim 1 wherein step (c) includes charging electrodes other than the first selected electrodes to the first polarity.

4. The method of deposition according to claim 1 further comprising the step of orienting the first substrate in relation to the plurality of liquid droplets charged to the first polarity wherein, in step (c), the plurality of liquid droplets are attracted toward the first selected electrodes in a direction different from the direction of the force of gravity.

5. The method of deposition according to claim 1 wherein each of the plurality of liquid droplets includes a solvent and step (c) includes selectively depositing the plurality of liquid droplets on the first selected electrodes before the solvent evaporates.

6. The method of deposition according to claim 1 wherein step (c) includes selectively depositing a predetermined amount of the display material on the first selected electrodes.

7. The method of deposition according to claim 6 wherein step (c) includes:

measuring a quantity of charge associated with the plurality of liquid droplets charged to the first polarity;

selectively controlling, responsive to the measured quantity of charge, at least one of

(1) charging of the first selected ones of the plurality of electrodes and

(2) a rate of forming the plurality of liquid droplets charged to the first polarity.

8. The method of deposition according to claim 6 wherein step (c) includes:

measuring a level of current applied to at least one of the first selected electrodes; and

providing a value corresponding to a quantity of the display material attracted to the at least one of the first selected electrodes responsive to the measured current level.

9. The method of deposition according to claim 8 wherein step (c) further includes the step of selectively controlling charging of the at least one of the first selected electrodes responsive to the value corresponding to the quantity of the material attracted to the at least one of the first selected electrodes.

10. The method of deposition according to claim 6 wherein step (c) includes charging each of the first selected electrodes with a respective predetermined quantity of charge wherein the amount of material deposited on each of the first selected electrodes corresponds to its respective predetermined quantity of charge.

11. The method of deposition according to claim 1 wherein step (b) comprises forming the plurality of liquid droplets including portions of the display material charged to the first polarity and the method further comprises the steps of:

(d) forming a plurality of portions of a further display material charged to the first polarity; and

(e) charging second selected electrodes of the plurality of electrodes to a second polarity to selectively attract the plurality of portions of the further display material to the second selected electrodes.

12. The method of deposition according to claim 11 wherein step (c) includes depositing the display material on one of a column electrode and a row electrode of a display structure and step (e) includes depositing the further display material on one of a column electrode and a row electrode of the display structure.

13. The method of deposition according to claim 11 wherein the first selected electrodes are exclusive of the second selected electrodes and the method of deposition further comprises the step of:

(f) charging the first selected electrodes to one of the first polarity and a neutral polarity whereby the plurality of portions of the further display material are selectively attracted to the second selected electrodes.

14. The method of deposition according to claim 1 wherein:

step (b) includes forming a plurality of portions of the material wherein each of the plurality of portions has a volume ranging between about 1.25×

10<sup>−

7</sup> cm³ and 1.25×

10<sup>−

13</sup> cm³; and

step (c) includes depositing a layer of the material having a thickness ranging between about 50nm and 500nm on the first selected electrodes.

15. The method of deposition according to claim 1 wherein the display material is a first display material and the method further comprises the step of forming a plurality of liquid droplets, including a second display material, charged to the first polarity and step (c) includes the step of depositing the liquid droplets of the first display material and the liquid droplets of the second display material on the first selected electrodes.

16. The method of deposition according to claim 1 further comprising the step of performing post deposition processing to improve attachment of the display material on the first selected electrodes.

17. The method of deposition according to claim 16 wherein the post deposition processing includes at least one of applying humidity, applying heat, applying solvent vapor and applying pressure to the first selected electrodes and the display material deposited thereupon.

18. A method of deposition comprising the steps of:

(a) providing a first substrate having a plurality of distinct electrodes;

(b) forming a plurality of liquid droplets including a solvent and portions of a material charged to a first polarity;

(c) selectively attracting the plurality of liquid droplets toward first selected electrodes of the plurality of distinct electrodes;

(d) evaporating the solvent to convert the plurality of liquid droplets including the material to form a plurality of particles of the material; and

(e) selectively depositing the plurality of particles of the material on the first selected electrodes.

19. The method of deposition comprising the steps of:

(a) providing a first substrate having a plurality of distinct electrodes;

(b1) forming a first solution including a hole transport material and a first solvent, and a second solution including an emissive material and a second solvent; and

(b2) forming a plurality of liquid droplets including the first and second solutions and charged to the first polarity, and

(c) selectively attracting the plurality of liquid droplets including the hole transport material and the emissive material toward first selected electrodes of the plurality of distinct electrodes and depositing the plurality of liquid droplets on the first selected electrodes wherein the droplets deposited on one of the first selected electrodes coalesce and the hole transport material and the emissive material in the droplets on the one of the first selected electrodes separate before the first and second solvents evaporate to form a hole transport material layer and an emissive material layer upon the one of the first selected electrodes.

20. The method of deposition according to claim 19 wherein step (b1) comprises forming a first solution including a hole transport material and a first solvent, and a second solution including an organic electroluminescent material and a second solvent wherein, in step (c), the hole transport material and the organic electroluminescent material in the droplets on the one of the first selected electrodes separate before the first and second solvents evaporate to form a hole transport material layer and an organic electroluminescent material layer upon the one of the first selected electrodes.