Electroluminescent devices with mixed electron transport materials
View Patent ↗An OLED device comprises a cathode, an anode, a light emitting layer, and on the cathode side of said emitting layer, a further layer, wherein the further layer is an electron-transporting layer containing: a) a first compound that has the lowest LUMO value of the compounds in the layer, the amount being greater than 40% by volume and less than 100% by volume of the layer; and b) at least one second compound that is a low voltage electron transport material, exhibiting a higher LUMO value than the first compound, the total amount of said compound(s) being less than 60% by volume and more than 0% by volume of the layer.
1. An OLED device comprising a cathode, an anode, a light emitting layer, and on the cathode side of said emitting layer, a further layer, wherein the further layer is an electron-transporting layer containing a mixture of:
a) a first compound that has the lowest LUMO value of the compounds in the layer, the amount being greater than 40% by volume and less than 100% by volume of the layer wherein the first compound is represented by formula V:
wherein:
R 1 , R 3 , R 4 , R 7 , R 9 , R 10 , represent hydrogen; R 2 and R 8 represent hydrogen or independently selected alkyl groups; R 5 , R 6 , R 11 , and R 12 represent independently selected aryl groups; and
b) at least one second compound that is a low voltage electron transport material, exhibiting a higher LUMO value than the first compound, the total amount of said compound(s) being less than or equal to 60% by volume and more than 0% by volume of the layer wherein the second compound is represented by Formula I:
wherein
M represents Al;
n is 3; and
Z independently in each occurrence represents the atoms completing a quinoline group.
2. The OLED device of claim 1 wherein neither the first nor second compounds comprise a triarylamine group.
3. The OLED device of claim 1 wherein said further layer is adjacent to said light emitting layer and said further layer is also adjacent to an electron-injecting layer.
4. The OLED device of claim 1 wherein said further layer is a non-emitting layer.
5. The OLED device of claim 1 wherein the first compound has a LUMO value of −2.40 eV or lower (more negative).
6. The OLED device of claim 1 wherein the first compound has a LUMO value of −2.70 eV or lower.
7. The OLED device of claim 1 wherein the first compound is present in an amount greater than or equal to 60% by volume and less than 100% by volume of the layer and the second compound(s) is present in a total amount less than or equal to 40% by volume and more than 0% by volume of the layer.
8. The OLED device of claim 7 wherein the first compound has a LUMO value of −2.40 eV or lower.
9. The OLED device of claim 7 wherein the second compound is tris(8-quinolinolato)aluminum (Ill).