# US 2019/0169452 A1 · Ester-Based Solvent Systems for Printable Organic Light-Emitting Diode Ink Formulations > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0169452 A1 - Document ID: US20190169452A1 - Status: Published application - Kind: A1 - Application number: 16/262,533 - Filed: 2019-01-30 - Published: 2019-06-06 - Earliest claimed: 2013-08-12 - Assignees: Kateeva, Inc. - Applicants: Kateeva, Inc. - Inventors: Inna Tregub; Tane Boghozian; Michelle Chan - Web page: https://patentgrep.com/patent/US20190169452A1 ## CPC - C09D 11/36: based on non-aqueous solvents - C09D 5/22: Luminous paints {(luminescent compositions C09K11/00)} - C09D 11/50: Sympathetic, colour changing or similar inks - C09D 11/52: Electrically conductive inks - C09K 11/025: {non-luminescent particle coatings or suspension media} - C09K 11/06: containing organic luminescent materials - H10K 50/11: characterised by the electroluminescent [EL] layers - H10K 71/135: {using ink-jet printing} - H10K 85/10: Organic polymers or oligomers - H10K 50/15: Hole transporting layers - C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES ## Abstract Ink compositions for forming active layers in an organic light-emitting diode are provided. Also provided are methods of forming active layers of an OLED using the ink compositions. The ink compositions comprise a solvent system in which a substantial majority of the solvent is comprised of one or more ester compounds. ## Claims ### Claim 1 A method of forming a hole transporting layer, a hole injection layer, or a light-emitting layer for an organic light-emitting diode, the method comprising: inkjet printing a layer of an ink composition in a pixel cell of an organic light-emitting diode pixel bank, the ink composition comprising a first component selected from a hole transporting material comprising a crosslinkable polymer, a conductive hole injection material; and an organic electroluminescent material, wherein the first component is dissolved in a solvent system, the solvent system comprising at least one ester, and further wherein the ink composition comprises from 0.1 to 5 weight percent of the first component and has a viscosity of 100 cPs or lower at 23° C.; and drying the layer of the ink composition under vacuum. ### Claim 2 (depends on 1) The method of claim 1, further comprising heating the layer of the ink composition. ### Claim 3 (depends on 1) The method of claim 1, wherein the ink composition comprises the organic electroluminescent material and the organic electroluminescent material is an organic polymer selected from polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, and polyfluorene derivatives. ### Claim 4 (depends on 1) The method of claim 1, wherein the ink composition comprises the hole transporting material and the hole transporting material is selected from polysilanes, polysilane derivatives, polysiloxane derivatives having an aromatic amine at the side chain or the main chain, pyrazoline derivatives, polythiophene, polythiophene derivatives, polypyrroles, polypyrrole derivatives, poly(2,5 thienylene vinylene), and poly(2,5 thienylene vinylene) derivatives. ### Claim 5 (depends on 1) The method of claim 1, wherein the ink composition comprises the conductive hole injection material and the conductive hole injection material is selected from phenylamines, starburst-type amines, phthalocyanines, and polyaniline. ### Claim 6 (depends on 1) The method of claim 1, wherein the pixel cell comprises a floor and a wall that defines the perimeter of the pixel cell, and further wherein the pixel cell and the wall are coated with surfactant. ### Claim 7 (depends on 1) The method of claim 1, wherein the hole transporting layer, the hole injection layer, or the light-emitting layer has a thickness that varies by no more than 10%. ### Claim 8 (depends on 3) The method of claim 3, wherein the light-emitting layer emits luminescence with a coefficient of variation of no greater than 20%. ### Claim 9 A method of forming a hole transporting layer and a light-emitting layer for an organic light-emitting diode, the method comprising: inkjet printing a layer of a first ink composition in a pixel cell of an organic light-emitting diode pixel bank, the first ink composition comprising a hole transporting material comprising a crosslinkable polymer, wherein the hole transporting material is dissolved in a solvent system, the solvent system comprising at least one ester, wherein the first ink composition comprises from 0.1 to 5 weight percent of the hole transporting material and has a viscosity of 100 cPs or lower at 23° C.; drying the layer of the first ink composition under vacuum; inkjet printing a layer of a second ink composition in the pixel cell, the second ink composition comprising an organic electroluminescent material dissolved in a second solvent system, the second solvent system comprising least one ester, wherein the second ink composition comprises from 0.1 to 5 weight percent of the organic electroluminescent material and has a viscosity of 100 cPs or lower at 23° C.; and drying the layer of the second ink composition under vacuum. ### Claim 10 (depends on 9) The method of claim 9, further comprising heating the layer of the first ink composition, whereby a hole transporting layer that is at least partially crosslinked is formed and heating the layer of the second ink composition, whereby a light emitting layer is formed. ### Claim 11 (depends on 10) The method of claim 10, wherein the crosslinkable polymer of the hole transporting layer is not fully crosslinked. ### Claim 12 (depends on 9) The method of claim 9, wherein the at least one ester of the first solvent system and the at least one ester of the second solvent system are the same ester. ### Claim 13 (depends on 9) The method of claim 9, further comprising inkjet printing a third ink composition comprising a conductive hole injection material dissolved in a solvent system in the pixel cell, the solvent system comprising at least one ester, and drying the layer of the third ink composition under vacuum. ### Claim 14 (depends on 13) The method of claim 13, further comprising heating the layer of the third ink composition, whereby a hole injection layer is formed.