Inverted OLED device with improved efficiency
View Patent ↗An inverted OLED device, comprising: a substrate; a cathode disposed on the substrate; an anode spaced from the cathode; at least one light-emitting layer disposed between the anode and the cathode; a hole-transporting layer disposed between the anode and the light-emitting layer(s); an electron-transporting layer disposed between the cathode and the light-emitting layer(s); a first electron-accepting layer disposed between the hole-transporting layer and the anode and including a first electron-deficient organic material constituting more than 50% by volume of the first electron-accepting layer and having a reduction potential greater than −0.5 V vs. a Saturated Calomel Electrode; and a second electron-accepting layer disposed between the electron-transporting layer and the cathode including a second electron-deficient organic material constituting more than 50% by volume of the second electron-accepting layer and having a reduction potential greater than −0.5 V vs. a Saturated Calomel Electrode.
1. An inverted OLED device, comprising in sequence:
a. a substrate;
b. a cathode in contact with the substrate;
c. second electron-accepting layer including a second electron-deficient organic material constituting more than 50% by volume of the second electron-accenting layer and having a reduction potential greater than −0.5 V vs. a Saturated Calomel;
D. an electron-transporting layer;
E. at least one light-emitting layer;
F. a hole-transporting layer;
g. a first electron-accepting layer disposed between the hole-transporting layer and the anode and including a first electron-deficient organic material constituting more than 50% by volume of the first electron-accepting layer and having a reduction potential greater than −0.5 V vs. a Saturated Calomel; and
h. an anode.
2. The inverted OLED device of claim 1 wherein the first or second electron-deficient organic material is a hexaazatriphenylene derivative.
3. The inverted OLED device of claim 2 wherein the hexaazatriphenylene derivative is hexacyanohexaazatriphenylene.
4. The inverted OLED device of claim 2 wherein both the first and second electron deficient organic material is hexacyanohexaazatriphenylene and constitutes substantially all of the volume of the first and second electron-accepting layers.
5. The inverted OLED device of claim 1 where in the reduction potential for the first or second electron deficient organic materials is greater than −0.1V.
6. The inverted OLED device of claim 1 wherein the anode includes aluminum and the cathode includes indium-tin oxide.
7. The inverted OLED device of claim 1 wherein the anode includes indium-tin oxide and the cathode includes aluminum and a layer of indium-tin oxide over the aluminum.
8. The inverted OLED device of claim 1 wherein the first electron-accepting layer is in direct contact with the anode.
9. A method of making an inverted OLED device, comprising:
a. providing a substrate;
b. forming a cathode directly on the substrate;
c. depositing a second electron-accepting layer over the cathode including a second electron-deficient organic material constituting more than 50% by volume of the second electron-accepting layer and having a reduction potential greater than −0.5 V vs. a Saturated Calomel Electrode;
d. depositing in sequence an electron-transporting layer over the second electron-accepting layer, one or more light-emitting layers over the electron-transporting layer, and a hole-transporting layer over the last-deposited light-emitting layer;
e. depositing a first electron-accepting layer over the hole-transporting layer and including a first electron-deficient organic material constituting more than 50% by volume of the first electron-accepting layer and having a reduction potential greater than −0.5 V vs. a Saturated Calomel Electrode; and
forming an anode in contact with the first electron-accepting layer.
10. The method of claim 9 wherein both the first and second electron deficient organic material is hexacyanohexaazatriphenylene and constitutes substantially all of the volume of the first and second electron-accepting layers.