Active OLED display, method of operating an active OLED display and compound

• US 10,312,464 B2
• Filed: 09/30/2015
• Issued: 06/04/2019
• Est. Priority Date: 09/30/2014
• Status: Active Grant

• Current Assignee: Novaled GmbH
• Original Assignee: Novaled GmbH
• Inventors: Rothe, Carsten, Rosenow, Thomas, Koehler, Martin, Zoellner, Mike, Haldi, Andreas, Canzler, Tobias
• Primary Examiner(s): Henry, Caleb E
• Application Number:
  US15/515,174
• Publication Number:
  US 20170222170A1
• Time in Patent Office: 1,343 Days
• Field of Search: 257 40
• CPC Class Codes: C07C 211/56 the carbon skeleton being further substituted by halogen atoms or by nitro or nitroso groups
• CPC Class Codes: H10K 50/155 comprising dopants
• CPC Class Codes: H10K 59/35 comprising red-green-blue [RGB] subpixels
• CPC Class Codes: H10K 85/631 Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine

Abstract

An active OLED display, comprising a plurality of OLED pixels, each of the OLED pixels comprising an anode, a cathode, and a stack of organic layers, wherein the stack of organic layers is provided between and in contact with the cathode and the anode and comprises an electron transport layer, a hole transport layer, and a light emitting layer provided between the hole transport layer and the electron transport layer, and a driving circuit configured to separately driving the pixels of the plurality of OLED pixels, wherein, for the plurality of OLED pixels, a common hole transport layer is formed by the hole transport layers provided in the stack of organic layers of the plurality of OLED pixels, the common hole transport layer comprising a hole transport matrix material and at least one electrical p-dopant, and the electrical conductivity of the hole transport material being lower than 1×10⁻³ S·m⁻¹ and higher than 1×10⁻⁸ S·m⁻¹.

Claims

1. An active OLED display, comprising

a plurality of OLED pixels, each of the OLED pixels comprising an anode, a cathode, and a stack of organic layers, wherein the stack of organic layers

is provided between and in contact with the cathode and the anode, and

comprises an electron transport layer, a hole transport layer, and a light emitting layer provided between the hole transport layer and the electron transport layer, and

a driving circuit configured for separately driving the pixels of the plurality of OLED pixels,

wherein, for the plurality of OLED pixels, a common hole transport layer is formed by the hole transport layers provided in the stack of organic layers of the plurality of OLED pixels, the common hole transport layer comprising a hole transport matrix material and an electrical p-dopant, and wherein the electrical conductivity of the common hole transport layer is lower than 1×

10<sup>−

3</sup> S·

m<sup>−

1</sup> and higher than 1×

10<sup>−

8</sup> S·

m<sup>−

1</sup>, and

wherein the common hole transport layer has a thickness of less than 50 nm.

2. The active OLED display according to claim 1, wherein the LUMO energy level of the electrical p-dopant, expressed in the absolute scale referring to vacuum energy level being zero, is at least 150 meV higher than the highest HOMO energy level of the one or more compounds forming the hole transport matrix material.

3. The active OLED display according to claim 1, wherein the LUMO energy level of the electrical p-dopant, expressed in the absolute scale referring to vacuum energy level being zero, is less than 600 meV above the highest HOMO energy level of the one or more compounds forming the hole transport matrix material.

4. The active OLED display according to claim 1, wherein the hole transport matrix material consists of one or more compounds having energies of their highest occupied molecular orbitals, expressed in the absolute scale referring to vacuum energy level being zero, in the range from −

4.8 eV to −

5.5 eV.

5. The active OLED display according to claim 1, wherein the common hole transport layer has a thickness of more than 3 nm.

6. The active OLED display according to claim 1, wherein the work function of the anode, expressed in the absolute scale referring to vacuum energy level being zero, is less than 500 meV above the highest LUMO energy level of the one or more compounds forming the p-dopant.

7. The active OLED display according to claim 1, wherein the stack of organic layers further comprises an electron blocking layer provided between the hole transport layer and the light emitting layer.

8. The active OLED display according to claim 7, wherein the electron blocking layer has a thickness of more than 30 nm.

9. The active OLED display according to claim 7, wherein the electron blocking layer has a thickness of less than 200 nm.

10. The active OLED display according to claim 7, wherein each of the one or more compounds forming the electron blocking layer has a HOMO level, expressed in the absolute scale referring to vacuum energy level being zero, higher than the HOMO level of any compound forming the hole transport matrix material of the common hole transport layer.

11. The active OLED display according to claim 7, wherein the hole transport matrix material of the common hole transport layer is provided with a hole mobility which is lower than a hole mobility of a matrix material of the electron blocking layer.

12. The active OLED display according to claim 1, wherein the hole transport matrix material of the common hole transport layer is selected from one or more compounds comprising a conjugated system of delocalized electrons, the conjugated system comprising lone electron pairs of at least two tertiary amine nitrogen atoms.

13. The active OLED display according to claim 1, wherein the light emitting layer comprises a plurality of separated sub-regions, each of the sub-regions being assigned to one of the pixels from the plurality of OLED pixels.

14. The active OLED display according to claim 1, wherein, for the plurality of OLED pixels, a common electron transport layer is formed by the electron transport layers provided in the stack of organic layers of the plurality of OLED pixels.

15. The active OLED display according to claim 14, wherein the common electron transport layer comprises an electron transport matrix material and an electrical n-dopant.

16. A method of operating an active OLED display having a plurality of OLED pixels according claim 1, wherein a driving circuit applies a driving current to each pixel of the plurality of OLED pixels, the driving current being different for neighbor OLED pixels at an operation time.

17. Compound having formula