Top-emitting OLED device with improved-off axis viewing performance
View Patent ↗A top-emitting OLED device with improved off-axis viewing includes a substrate; a reflective, substantially opaque, and conductive anode including a metal or metal alloy or both formed over the substrate; at least one organic layer formed over the anode and including an electroluminescent material; a cathode including a semitransparent metallic layer provided over the organic layer wherein the semitransparent metallic layer includes a low reflectivity metal; an light transmissive layer provided over the cathode; and the cathode and light transmissive layer being selected to reduce the color shift with respect to an off-axis viewing angle.
1. A top-emitting OLED device with improved off-axis viewing comprising:
(a) a substrate;
(b) a reflective, substantially opaque, and conductive anode including a metal or metal alloy or both formed over the substrate;
(c) at least one organic layer formed over the anode and including an electroluminescent material;
(d) a cathode including a semitransparent metallic layer provided over the organic layer wherein the semitransparent metallic layer is a low reflectivity metal or metal alloy having a bulk reflectivity of about 50% or less; and
(e) a light transmissive layer provided over the cathode.
2. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the cathode includes a rare earth metal, Ge, Os, Rh, Se, Si, Ta, Ti, V, W or Zr or alloys thereof.
3. The top-emitting OLED device with improved off-axis viewing of claim 2 wherein the rare earth metal includes a lanthanide.
4. The top-emitting OLED device with improved off-axis viewing of claim 3 wherein the lanthanide is Yb.
5. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the cathode includes a thin layer of an alkali metal or an alkaline earth metal under the semitransparent metallic layer.
6. The top-emitting OLED device with improved off-axis viewing of claim 5 wherein the alkali metal is Li.
7. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the cathode includes an ultrathin electron injecting layer greater than 0 and less than 2 nm between the organic layer and the semitransparent metallic layer.
8. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the thickness of the semitransparent metallic layer is in a range of 5 to 50 nm.
9. The top-emitting OLED device with improved off-axis of claim 1 wherein the light transmissive layer includes highly transparent materials in a single or a multilayer structure.
10. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the light transmissive layer includes conducting or non-conducting materials.
11. The top-emitting OLED device with improved off-axis viewing of claim 1 , wherein the light transmissive layer is in contact with the semitransparent metallic layer.
12. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the light transmissive layer includes metal oxides, metal nitrides, metal fluorides, metal carbides or metal borides or mixtures thereof.
13. The top-emitting OLED device with improved off-axis viewing of claim 12 wherein the light transmissive layer includes organic materials.
14. The top-emitting OLED device with improved off-axis viewing of claim 13 wherein the organic materials includes Alq or NPB or both.
15. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the reflective, substantially opaque, and conductive anode includes Ag, Al, Mg, Zn, Rh, Ru, Ir, Au, Cu, Pd, Ni, Cr, Pt, Co, Te, Mo, Hf, Fe, Mn, Nb, Ge, Os, Ti, V or W, or alloys or mixtures thereof.
16. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the thickness of the light transmissive element is a range from 5 nm to 60 nm.
17. The top-emitting OLED device with improved off-axis viewing of claim 1 further including a hole injection layer and a hole transport layer: the hole injection layer is in contact with the anode and the hole transport layer being disposed over the hole injection layer.
18. The top-emitting OLED device with improved off-axis viewing of claim 17 wherein the hole injection layer includes CF x , ITO, IZO, Pr 2 O 3 , TeO 2 , CuPc, SiO 2 , VO x , MoO x , or Ru 2 O 3 or mixtures thereof.
19. The top-emitting OLED device with improved off-axis viewing of claim 17 wherein the hole transport layer is NPB.
20. The top-emitting OLED device with improved off-axis viewing of claim 17 wherein the thickness of the hole-transport layer is 30 to 80 nm or 160 to 230 nm.
21. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the total thickness of organic layers is 90 to 140 nm or 220 to 290 nm.
22. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the thickness of anode is in a range of from 50 nm to 200 nm.
23. The top-emitting OLED device with improved off-axis viewing of claim 1 wherein the thickness of the light transmissive layer is selected to improve luminance efficiency and reduce off-axis color shift.