Organic electroluminescence element

• US 20090218561A1
• Filed: 02/19/2009
• Published: 09/03/2009
• Est. Priority Date: 03/03/2008
• Status: Active Grant

• Current Assignee: UDC Ireland Limited (Universal Display Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: KITAMURA, Yoshitaka, TOBISE, Manabu, KINOSHITA, Masaru
• Granted Patent: US 8,174,001 B2
• Time in Patent Office: Days
• US Class Current: 257/13
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 2102/103 comprising indium oxides, e.g. ITO
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 71/30 Doping active layers, e.g. electron transporting layers
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/346 comprising platinum

Abstract

An organic electroluminescence element including at least two light-emitting layers disposed between an anode and a cathode, wherein the at least two light-emitting layers include a light-emitting layer A that contains an electron transporting light-emitting material and a hole transporting host material, wherein a concentration of the electron transporting light-emitting material gradually increases from an anode side toward a cathode side of the light-emitting layer A, and a light-emitting layer B that contains a hole transporting light-emitting material and an electron transporting host material, wherein a concentration of the hole transporting light-emitting material gradually decreases from an anode side toward a cathode side of the light-emitting layer B. An organic EL element with high light-emission efficiency and excellent durability is provided.

Claims

1. An organic electroluminescence element comprising at least two light-emitting layers disposed between an anode and a cathode, wherein the at least two light-emitting layers include:

(1) a light-emitting layer A that contains an electron transporting light-emitting material and a hole transporting host material, wherein a concentration of the electron transporting light-emitting material gradually increases from an anode side toward a cathode side of the light-emitting layer A; and

(2) a light-emitting layer B that contains a hole transporting light-emitting material and an electron transporting host material, wherein a concentration of the hole transporting light-emitting material gradually decreases from an anode side toward a cathode side of the light-emitting layer B.

2. The organic electroluminescence element according to claim 1, wherein the light-emitting layer A and the light-emitting layer B are disposed adjacent to each other.

3. The organic electroluminescence element according to claim 1, wherein the light-emitting layer A is disposed closer to the anode than the light-emitting layer B, and the light-emitting layer B is disposed closer to the cathode than the light-emitting layer A.

4. The organic electroluminescence element according to claim 1, wherein:

in the light-emitting layer A, a concentration of the electron transporting light-emitting material, which gradually increases from the anode side toward the cathode side, is from 0% to 50% in an interface region of the light-emitting layer A on the anode side, with respect to a concentration thereof in an interface region of the light-emitting layer A on the cathode side; and

in the light-emitting layer B, a concentration of the hole transporting light-emitting material, which gradually decreases from the anode side toward the cathode side, is from 0% to 50% in an interface region of the light-emitting layer B on the cathode side, with respect to a concentration thereof in an interface region of the light-emitting layer B on the anode side.

5. The organic electroluminescence element according to claim 1, wherein the electron transporting light-emitting material comprises a metal complex having a tri- or higher-dentate ligand.

6. The organic electroluminescence element according to claim 5, wherein the metal complex having a tri- or higher-dentate ligand is a compound represented by the following formula (I):

wherein in formula (I), M¹¹ represents a metal ion;

L¹¹ to L¹⁵ each independently represent a ligand which coordinates to M¹¹;

an atomic group may further exist between L¹¹ and L¹⁴ to form a cyclic ligand;

L¹⁵ may bond to both of L¹¹ and L¹⁴ to form a cyclic ligand;

Y¹¹, Y¹² and Y¹³ each independently represent a linking group, a single bond or a double bond;

when Y¹¹, Y¹² or Y¹³ is a linking group, bonds between L¹¹ and Y¹², Y¹² and L¹², L¹² and Y¹¹, Y¹² and L¹³, L¹³ and Y¹³, and Y¹³ and L¹⁴ each independently represent a single bond or a double bond;

n¹¹ is from 0 to 4; and

bonds between M¹¹ and L¹¹ to L¹⁵ are each independently a coordination bond, an ionic bond or a covalent bond.

7. The organic electroluminescence element according to claim 6, wherein in formula (I), M¹¹ is a platinum ion.

8. The organic electroluminescence element according to claim 1, wherein the hole transporting light-emitting material comprises an iridium complex.