OLEDs utilizing direct injection to the triplet state
First Claim
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1. An organic light emitting device comprising:
- a) an anode;
b) a cathode;
c) an emissive layer disposed between the anode and the cathode, the emissive layer comprising i) a phosphorescent dopant having a ground state, a triplet state, and a higher lying molecular excited state; and
ii) an emissive layer host having an emissive layer host HOMO energy level and an emissive layer host LUMO energy level;
d) a transport layer disposed adjacent to the emissive layer, the transport layer comprising a first material having a first material HOMO energy level and a first material LUMO energy level, wherein an electron-hole pair recombine, without populating the higher lying molecular excited state, across an energy separation that is about equal to the triplet energy of the phosphorescent dopant.
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Abstract
The present invention relates to OLEDs utilizing direct injection to the triplet state. The present invention also relates to OLEDs utilizing resonant injection and/or stepped energy levels.
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Citations
19 Claims
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1. An organic light emitting device comprising:
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a) an anode;
b) a cathode;
c) an emissive layer disposed between the anode and the cathode, the emissive layer comprising i) a phosphorescent dopant having a ground state, a triplet state, and a higher lying molecular excited state; and
ii) an emissive layer host having an emissive layer host HOMO energy level and an emissive layer host LUMO energy level;
d) a transport layer disposed adjacent to the emissive layer, the transport layer comprising a first material having a first material HOMO energy level and a first material LUMO energy level, wherein an electron-hole pair recombine, without populating the higher lying molecular excited state, across an energy separation that is about equal to the triplet energy of the phosphorescent dopant. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An organic light emitting device comprising:
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a) an anode;
b) a cathode;
c) an emissive layer disposed between the anode and the cathode, the emissive layer comprising i) a phosphorescent dopant having a ground state, a triplet state, and a higher lying molecular excited state; and
ii) an emissive layer host having an emissive layer host HOMO energy level and an emissive layer host LUMO energy level;
d) a transport layer disposed adjacent to the emissive layer, the transport layer comprising a plurality of materials, each material having a HOMO energy level and a LUMO energy level, wherein at least one energy level of each of the plurality of materials together form a series of energy steps leading to at least one energy level in the emissive layer, wherein each step in the series of energy steps is no more than about 0.2 eV. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method comprising:
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a) depositing an anode over a substrate;
b) depositing an emissive layer over the anode, wherein the emissive layer comprises i) a phosphorescent dopant having a ground state, a triplet state, and a higher lying molecular excited state; and
ii) an emissive layer host having an emissive layer host HOMO energy level and an emissive layer host LUMO energy level;
c) depositing an electron transport layer over the emissive layer, wherein the electron transport layer comprises an electron transport material having an electron transport LUMO energy level;
d) depositing a cathode over the electron transport layer, wherein at least one of the emissive layer host LUMO and the electron transport LUMO is no more than about 0.1 eV below the triplet state and at least about 0.2 eV below the higher lying molecular excited state.
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Specification