Charge transport material
A charge transport material containing a charge transport substance that is composed of a compound represented by formula (1) and another charge transport substance that is composed of a charge transport compound having a molecular weight of 200-9,000 exhibits good solubility in an organic solvent. A charge transport varnish, from which a charge transport thin film having excellent charge transport properties, flatness and uniformity is formed with good reproducibility, is able to be prepared by dissolving the above-described charge transport material in an organic solvent.
1. A charge-transporting varnish which comprises a charge-transporting material and an organic solvent,
wherein the charge-transporting material comprising a charge-transporting substance consisting of a compound of formula (1),
and a charge-transporting substance consisting of a charge-transporting compound having a molecular weight of 200 to 9,000 (exclusive of a compound of formula (1)) and a dopant substance, and
wherein the charge-transporting material is dissolved in the organic solvent.
2. The charge-transporting varnish of claim 1 , wherein the charge-transporting compound is at least one compound selected from the group consisting of arylamine derivatives, thiophene derivatives and pyrrole derivatives.
3. The charge-transporting varnish of claim 1 , wherein the charge-transporting compound having a molecular weight of 200 to 9,000 is a compound of formula (2) or (3)
wherein, R 1 and R 2 are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, or an alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms, alkynyl group of 2 to 20 carbon atoms, aryl group of 6 to 20 carbon atoms or heteroaryl group of 2 to 20 carbon atoms which may be substituted with a halogen atom,
Ph 1 represents a group of the formula (P1)
wherein, R 3 to R 6 are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, or an alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms, alkynyl group of 2 to 20 carbon atoms, aryl group of 6 to 20 carbon atoms or heteroaryl group of 2 to 20 carbon atoms which may be substituted with a halogen atom,
Ar 1 is independently a group represented by any of formulas (B1) to (B11)
wherein, R 7 to R 27 , R 30 to R 51 and R 53 to R 154 are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, or a diphenylamino group, alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms, alkynyl group of 2 to 20 carbon atoms, aryl group of 6 to 20 carbon atoms or heteroaryl group of 2 to 20 carbon atoms which may be substituted with a halogen atom; R 28 and R 29 are each independently an aryl group of 6 to 20 carbon atoms or a heteroaryl group of 2 to 20 carbon atoms which may be substituted with Z 1 ; R 52 is a hydrogen atom, an alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms or alkynyl group of 2 to 20 carbon atoms which may be substituted with Z 4 , or an aryl group of 6 to 20 carbons or heteroaryl group of 2 to 20 carbon atoms which may be substituted with Z 1 ; Z 1 is a halogen atom, a nitro group, a cyano group, or an alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms or alkynyl group of 2 to 20 carbon atoms which may be substituted with Z 2 ; Z 2 is a halogen atom, a nitro group, a cyano group, or an aryl group of 6 to 20 carbon atoms or heteroaryl group of 2 to 20 carbon atoms which may be substituted with Z 3 ; Z 3 is a halogen atom, a nitro group or a cyano group; Z 4 is a halogen atom, a nitro group, a cyano group, or an aryl group of 6 to 20 carbon atoms or heteroaryl group of 2 to 20 carbon atoms which may be substituted with Z 5 ; Z 5 is a halogen atom, a nitro group, a cyano group, or an alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms or alkynyl group of 2 to 20 carbon atoms which may be substituted with Z 3 , and Ar 4 independently represents an aryl group of 6 to 20 carbon atoms which may be substituted with a di(C 6-20 aryl)amino group,
Ar 2 is independently a group of any one of formulas (A1) to (A18)
wherein, R 155 is a hydrogen atom, an alkyl group of 1 to 20 carbon atoms, alkenyl group of 2 to 20 carbon atoms or alkynyl group of 2 to 20 carbon atoms which may be substituted with Z 4 , or an aryl group of 6 to 20 carbons or heteroaryl group of 2 to 20 carbon atoms which may be substituted with Z 1 ; R 156 and R 157 are each independently an aryl group of 6 to 20 carbon atoms or heteroaryl group of 2 to 20 carbon atoms which may be substituted with Z 1 ; DPA is a diphenylamino group; and Ar 4 , Z 1 and Z 3 to Z 5 are as defined above,
Ar 3 is a group having any of formulas (C1) to (C8)
wherein, DPA is as defined above,
k is an integer from 1 to 10, and
l represents 1 or 2.
4. The charge-transporting varnish of claim 1 which further comprises an organosilane compound.
5. A charge-transporting thin film produced using the charge-transporting varnish of claim 1 .
6. An organic electroluminescent device comprising the charge-transporting thin film of claim 5 .
7. A method of producing a charge-transporting thin film, which method is characterized by applying the charge-transporting varnish of claim 1 onto a substrate, and drying the applied varnish.
8. A method for increasing the flatness of a charge-transporting thin film formed using a compound of formula (1)
the method being characterized by using a charge-transporting varnish that includes a charge-transporting material containing a charge-transporting substance consisting of a compound of formula (1), a charge-transporting substance consisting of a charge-transporting compound having a molecular weight of 200 to 9,000 (exclusive of a compound of formula (1)) and a dopant substance and includes also an organic solvent, wherein the charge-transporting material is dissolved in the organic solvent.
9. A method for reducing the driving voltage of an organic electroluminescent device having an anode, a cathode, and a plurality of functional layers situated between these electrodes that include a light-emitting layer, a hole-injecting layer and a hole-transporting layer, the method being characterized by using a charge-transporting varnish that includes a charge-transporting material containing a charge-transporting substance consisting of a compound of formula (1),
a charge-transporting substance consisting of a charge-transporting compound having a molecular weight of 200 to 9,000 (exclusive of a compound of formula (1)) and a dopant substance and includes also an organic solvent, wherein the charge-transporting material is dissolved in the organic solvent.