Electroluminescent device including gallium complexes
An OLED device comprises an anode, a light emitting layer, a first layer, a second layer contiguous to the first layer, and a cathode, in that order. The first layer includes a first complex comprising gallium or another group 13 metal and the second layer includes a second complex also comprising gallium and wherein the second complex has a more negative LUMO than the first complex. Such materials can provide an improvement in one or more of luminance, drive voltage, and stability.
1 . An OLED device comprising an anode, a light emitting layer, a first layer, a second layer contiguous to the first layer, and a cathode, in that order, and wherein the first layer includes a first complex comprising gallium and the second layer includes a second complex also comprising gallium and wherein the second complex has a more negative LUMO than the first complex.
2 . The device of claim 1 wherein the first layer also contains a second gallium complex having an equal or more positive LUMO than the second layer gallium complex.
3 . The device of claim 1 wherein the first complex is a gallium complex that comprises a 2-phenylimidazole group
4 . The device of claim 1 wherein the second complex is a gallium complex that comprises a 2-phenylbenzimidazole group.
5 . The device of claim 1 wherein the difference in the LUMO value of the first and second complexes is 0.1 eV or greater.
6 . The device of claim 1 wherein the difference in the LUMO value of the first and second complexes is 0.2 eV or greater.
7 . The device of claim 1 wherein the first layer is contiguous to a light-emitting layer.
8 . The device of claim 1 wherein the light-emitting layer includes a host material, and wherein the host material has a LUMO value that is more negative than the LUMO value of the first complex.
9 . The device of claim 1 wherein the light-emitting layer includes a host material, and wherein the difference in LUMO values between the host material and the first complex is 0.1 eV or less.
10 . The device of claim 1 wherein the second layer is contiguous to an electron-injecting layer.
11 . The device of claim 1 wherein the first or second complex is represented by Formula (1):
wherein:
each Z a and each Z b is independently selected and each represents the atoms necessary to complete an unsaturated ring; and
Z a and Z b are directly bonded to one another provided Z a and Z b may be further linked together to form a fused ring system.
12 . The device of claim 11 wherein each Z a and each Z b represents the atoms necessary to form an independently selected aromatic ring group.
13 . The device of claim 11 wherein the first complex and the second complex are both represented by Formula (1), provided at least one Z a or Z b in the first complex is different in the second complex.
14 . The device of claim 1 wherein the first or second complex is represented by Formula (2):
wherein:
each Z 1 through Z 7 independently represents N or C—Y; and
each Y represents hydrogen or an independently selected substituent, provided that two Y substituents may join to form a ring group.
15 . The device of claim 14 wherein at least one of Z 1 through Z 3 represents N and wherein Z 1 through Z 3 represent C—Y.
16 . The device of claim 1 wherein the first complex is represented by Formula (3a) and the second complex is represented by Formula (3b):
wherein:
each r 1 may be the same or different and each represents a substituent and n is 0-2;
each r 2 , r 3 , and r 4 may be the same or different and each represents a substituent, provided adjacent substituents may combine to form a ring group and m, p, and q are independently 0-4.
17 . The device of claim 1 wherein the second layer comprises an alkali metal material.
18 . The device of claim 17 wherein the alkali metal material comprises lithium.
19 . The device of claim 1 wherein the light-emitting layer includes a material that emits blue or blue-green light.
20 . The device of claim 1 wherein the light-emitting layer includes a host material that comprises an anthracene group.
21 . The device of claim 1 wherein the light-emitting layer includes a host material that comprises an anthracene group bearing independently selected aromatic substituents in the 2-, 9-, and 10-positions.
22 . The device of claim 1 wherein the first layer also contains any group 13 metal complex having an equal or more positive LUMO than the second layer gallium complex.
23 . An OLED device comprising an anode, a light emitting layer, a first layer, a second layer contiguous to the first layer, and a cathode, in that order, and wherein the first layer includes a first complex comprising a group 13 metal complex and the second layer includes a complex comprising gallium and wherein the gallium complex has a more negative LUMO than the group 13 metal complex.
24 . The device of claim 23 wherein the group 13 metal is aluminum.
25 . The device of claim 23 wherein the first complex is represented by Formula (E):
wherein:
M represents a metal; and
n is an integer of from 1 to 4; and
Z independently in each occurrence represents the atoms completing a nucleus having at least two fused aromatic rings: and
the second complex is represented by Formula (1):
wherein:
each Z a and each Z b is independently selected and each represents the atoms necessary to complete an unsaturated ring; and
Z a and Z b are directly bonded to one another provided Z a and Z b may be further linked together to form a fused ring system.
26 . The device of claim 25 where the first complex is tris(8-quinolinolato)aluminum (III) (Alq).
27 . The device of claim 23 wherein the second layer further comprises an alkali metal material.
28 . The device of claim 23 wherein there is a thin layer of between 5 to 25 angstroms contiguous to the 2 nd gallium containing layer on the cathode side.
29 . The device of claim 28 wherein the thin layer comprises tris(8-quinolinolato)aluminum (III) (Alq).