Organic electroluminescent element, material for positive hole injecting layer, and organic electroluminescent display
View Patent ↗The present invention relates to highly reliable organic EL elements that can provide higher luminance with lower voltage and exhibit lower leak current at negative biases and appropriate diode properties. The organic EL element comprises a positive hole injecting layer, and a perfluoropolyether compound is incorporated into the positive hole injecting layer. Preferably, the perfluoropolyether compound is expressed by formula (1) or (2), R 1 —Rf—R 2 formula (1) Rf—R 3 formula (2) in which, R 1 , R 2 , and R 3 represents one of a hydrogen atom, a fluorine atom, and a substituted group; Rf represents the perfluoropolyether skeleton expressed by the formula (3), in which, R 4 and R 5 represent general formula —C p F 2p+1 ; n, m, x, and y are each an integer.
1. An organic EL element comprising an organic thin film layer between a positive electrode and a negative electrode,
wherein the organic thin film layer comprises:
a positive hole injecting layer,
a positive hole transporting layer, and
a light emitting layer,
wherein a perfluoropolyether compound is incorporated into the positive hole injecting layer.
2. The organic EL element according to claim 1 , wherein the perfluoropolyether skeleton in the perfluoropolyether compound is partially hydrogenated.
3. The organic EL element according to claim 1 , wherein the perfluoropolyether compound is an amine salt of perfluoropolyether.
4. The organic EL element according to claim 1 , wherein the perfluoropolyether compound is expressed by one of formulas (1) and (2),
R 1 —Rf—R 2 formula (1)
Rf—R 3 formula (2)
in which, R 1 , R 2 , and R 3 in the formulas (1) and (2) may be identical or different from each other, and each represents one of a hydrogen atom, a fluorine atom, and a substituted group; Rf represents the perfluoropolyether skeleton expressed by the formula (3),
in which, R 4 and R 5 in the formula (3) may be identical or different each other, and each represents general formula —C p F 2p+1 (“p” is an integer of 0 or more); “n” and “m” may be identical or different from each other, and are each an integer of 0 or more, “x” and “y” may be identical or different from each other, and are each an integer of 1 or more.
5. The organic EL element according to claim 4 , wherein the R 1 to R 3 in the formulas (1) and (2) are each selected from the group consisting of alkyl groups, aralkyl groups, alkenyl groups, aryl groups, cyano groups, amino groups, acyl groups, alkoxy carbonyl groups, carboxyl group, alkoxy groups, alkyl sulfonyl groups, hydroxyl group, amide groups, aryloxy groups, aromatic hydrocarbon ring groups, aromatic heterocyclic groups, and groups expressed by formula (4),
in which, in the formula (4), R 6 represents a hydrocarbon group; “a” represents an integer of 0 or more; R 7 to R 10 may be identical or different from each other, and each represents one of a hydrogen atom, a fluorine atom, and hydrocarbon groups.
6. The organic EL element according to claim 1 , wherein the weight-averaged molecular weight of the perfluoropolyether compound is 500 to 10000.
7. The organic EL element according to claim 1 , wherein the thickness of the positive hole injecting layer is 0.1 to 10 nm thick.
8. The organic EL element according to claim 1 , wherein the organic thin film layer comprises a positive hole injecting layer, a positive hole transporting layer, and a light emitting layer in turn from the side of the positive electrode, the ionization potential in the positive hole injecting layer is lower than the ionization potential in the positive electrode and higher than the ionization potential in the positive hole transporting layer at the highest occupied molecular orbital (HOMO).
9. The organic EL element according to claim 8 , wherein the ionization potential in the positive hole injecting layer is 4.8 to 5.6 eV.
10. An organic EL display comprising an organic EL element,
wherein the organic EL element comprises an organic thin film layer between a positive electrode and a negative electrode,
wherein the organic thin film layer comprises:
a positive hole injecting layer,
a positive hole transporting layer, and
a light emitting layer,
wherein a perfluoropolyether compound is incorporated into the positive hole injecting layer.
11. The organic EL display according to claim 10 , wherein the organic EL display is formed into one of a passive matrix panel and an active matrix panel.