Claims
- 1. A method of forming a compacted pellet of organic materials adaptable for making an organic layer on a structure which will form part of an OLED display, comprising the steps of:
(a) providing a sublimable organic material in a powder form; (b) providing a thermally insulating and non-sublimable inorganic material in a powder form; (c) forming a mixture of the sublimable organic powder and thermally insulating and non-sublimable inorganic powder; (d) placing such mixture into a die and using two punches, a lower and an upper punch, to apply sufficient pressure to the mixture to cause the mixture of powders to consolidate into a solid pellet; (e) applying heat to the die during or prior to applying pressure by the opposing punches to aid in causing the mixture of powders to consolidate into a solid compacted pellet, and (f) removing the pellet from the die.
- 2. The method of claim 1, wherein the mixture includes at least one sublimable organic material and one thermally insulating non-sublimable inorganic material.
- 3. The method of claim 1, wherein the mixture includes more than one sublimable organic materials comprising at least one host and one dopant and at least one thermally insulating non-sublimable inorganic material.
- 4. A method of making an OLED display wherein emission layer is deposited using a compacted cylindrical pellet of organic materials comprising the steps of:
(a) providing a compacted cylindrical pellet of organic material including a mixture of at least one host and one dopant along with non-sublimable and thermally insulating inorganic material; (b) placing such a compacted cylindrical pellet inside a receptacle disposed in a physical vapor deposition chamber; (c) positioning a substrate of a partially formed OLED device in the physical deposition chamber in a spaced relationship with respect to the receptacle; (d) evacuating the chamber to a reduced pressure; (e) applying heat to a surface of the compacted cylindrical pellet of organic material by electrically energizing the heater disposed in the evaporation source to cause at least a portion to sublime to provide a mixture of vapors of the organic materials including the host and the dopant(s) to form an emission layer on the substrate; and (f) rotating the compacted cylindrical pellet after a certain instant in order to expose a fresh portion of organic materials on the pellet to the heater and discarding the non-sublimable thermally insulating inorganic material during the process of rotation.
- 5. The method of claim 4 wherein the thermally insulating and non-sublimable inorganic material includes
(g) zirconia; or (h) alumina, or (i) silica, or (j) titanis, or (k) magnesia, or mixtures thereof.
- 6. A method of making an OLED device using the compacted pellets of claim 1 comprising the steps of:
(g) subliming organic material from the top surface of the compacted cylindrical pellet and maintaining the bottom surface of the compacted cylindrical pellet at a lower temperature than the top surface with the temperature difference between the top and bottom surfaces being at least 100° C.
- 7. The method of claim 6 further including the step of cooling the bottom surface of the compacted cylindrical pellet.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Reference is made to commonly assigned U.S. patent application Ser. No 09/898,369 filed Jul. 3, 2001 entitled “Method of Handling Organic Material in Making An Organic Light-Emitting Device” by Van Slyke et al; U.S. patent application Ser. No. 10/073,690 filed Feb. 11, 2002, entitled “Using Organic Materials in Making An Organic Light-Emitting Device” by Ghosh et al, U.S. patent application Ser. No. 10/195,947 filed Jul. 16, 2002, entitled “Compacting Moisture-Sensitive Organic Material in Making An Organic Light-Emitting Device” by Ghosh et al, U.S. patent application Ser. No. 10/226,600 filed Aug. 23, 2002, entitled “Solid Compacted Pellet of Organic Material for Vacuum Deposition of OLED displays and Method of Making Same” by Ghosh et al, and U.S. patent application Ser. No. 10/348,118 filed Jan. 17, 2003, entitled “Using Compacted Organic Materials In Making White Light Emitting OLEDS” by Ghosh et al, the teachings of which are incorporated herein.