Manufacturing of a thin film inorganic light emitting diode

• US 6,737,293 B2
• Filed: 01/16/2002
• Issued: 05/18/2004
• Est. Priority Date: 02/07/2001
• Status: Expired due to Fees

• Current Assignee: Agfa-Gevaert N.V.
• Original Assignee: Agfa-Gevaert N.V.
• Inventors: Andriessen, Hieronymus
• Primary Examiner(s): Pham, Long
• Assistant Examiner(s): Le, Thao X.
• Application Number:
  US10/050,667
• Publication Number:
  US 20020153830A1
• Time in Patent Office: 853 Days
• Field of Search: 438/792, 438/7, 438/24, 438/48, 438/29, 257/80, 257/40, 257/98, 257/102-103, 313/502-506, 477/66, 445/24, 117/68, 117/63
• US Class Current: 438/99
• CPC Class Codes: C01G 9/08 Sulfides
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/0062 for devices with an active region comprising only III-V compounds
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/18 within the light emitting region
• CPC Class Codes: H01L 33/28 containing only elements of Group II and Group VI of the Periodic Table
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: Y10T 24/1494 Wire

Abstract

Nanoparticle dispersions of ZnS doped with a luminescent center are prepared by precipitation from aqueous solutions. When such dispersions are coated between conductive electrodes a Thin Film Inorganic Light Emitting Diode device is obtained.

Claims

1. A method for manufacturing a Thin Film Inorganic Light Emitting Diode device, said method comprising the following steps, in order:

(1) preparing a nanoparticle dispersion of ZnS doped with a luminescent centre by precipitation from appropriate aqueous solutions comprising zinc ions, sulfide ions and dopant ions,

(2) washing said dispersion of doped ZnS to remove non-precipitated ions,

(3) coating onto a first conductive electrode said washed dispersion of doped ZnS, optionally after admixture with a binder,

(4) applying on top of said coated layer resulting from step (3) a second conductive electrode, with the proviso that at least one of said first and second electrode is transparent.

2. A method according to claim 1 wherein said precipitation of step (1) is performed according to the double jet principle whereby a first solution containing zinc ions and a second solution containing sulfide ions are added together to a third solution.

3. A method according to claim 2 wherein said first solution also contains said dopant ions.

4. A method according to claim 1 wherein said dopant ions are Cu²⁺ ions.

5. A method according to claim 1 wherein said dopant ions are Cu⁺ ions.

6. A method according to claim 1 wherein said dopant ions are Mn²⁺ ions.

7. Method according to claim 1 wherein said washing of said dispersion of doped ZnS is performed by an ultrafiltration step, ultrafiltration step and a diafiltration step, or a diafiltration step.

8. Method according to claim 7 wherein said ultrafiltration step, ultrafiltration step and a diafiltration step, or a diafiltration step is (are) performed in the presence of a compound preventing agglomeration of nanoparticles.

9. A method according to claim 8 wherein said compound preventing the agglomeration of nanoparticles is a polyphosphate or polyphosphoric acid.

10. A method according to claim 1 wherein said first electrode is an Indium Tin Oxide (ITO) electrode.

11. A method according to claim 1 wherein said first electrode is a foil comprising a polythiophene/polyanion complex.

12. A method according to claim 11 wherein said polythiophene/polyanion complex is a poly(3,4-ethylenedioxythiophene)/polystyrene sulphonate complex.

13. A method according to claim 1 wherein said second conductive electrode is an aluminum electrode applied by vacuum deposition.

14. A Thin Film Inorganic Light Emitting Diode device manufactured according to a method for manufacturing a Thin Film Inorganic Light Emitting Diode device, said method comprising the following steps, in order:

(1) preparing a nanoparticle dispersion of ZnS doped with a luminescent center by precipitation from appropriate aqueous solutions comprising zinc ions, sulfide ions and dopant ions,

(2) washing said dispersion of doped ZnS to remove non-precipitated ions,

(3) coating onto a first conductive electrode said washed dispersion of doped ZnS, optionally after admixture with a binder, and

(4) applying on top of said coated layer resulting from step (3) a second conductive electrode, with the proviso that at least one of said first and second electrodes is transparent.