Fluorescent organic light emitting elements having high efficiency
The present invention relates to organic light emitting elements, comprising thermally activated delayed fluorescence (TADF) emitters and/or hosts of formula which have a sufficiently small energy gap between S 1 and T 1 (ΔE ST ) to enable up-conversion of the triplet exciton from T 1 to S 1 . The organic light emitting elements show high electroluminescent efficiency.
1 . A compound of formula I
wherein
X is independently in each occurrence O, S or NR 9 ,
Y 1 , Y 2 , Y 3 and Y 4 are independently of each other a direct bond, or a group of formula -[A 1 ]-[A 2 ] y -, wherein
A 1 and A 2 are independently of each other —CH═CH—, —C≡C— or a C 6 -C 10 arylene group, which may optionally be substituted by one or more C 1 -C 25 alkyl groups; y is 0, or 1;
R 1 , R 2 , R 3 and R 4 are independently of each other H, D, F, Cl, a C 1 -C 25 alkyl group, a C 1 -C 25 alkoxy group, a C 6 -C 10 aryloxy group, or a donor group of formula
X 1 is O, S, N(R 15 ), C(═O), C(R 16 )(R 17 ), B(R 18 ), or Si(R 19 )(R 20 ),
R 9 is H, a C 1 -C 25 alkyl group, or a C 6 -C 10 aryl group;
R 10 , R 11 , R 21 and R 21′ are independently of each other H, D, F, Cl, or a C 1 -C 25 alkyl group;
R 15 , R 16 , R 17 , R 18 , R 19 and R 20 are independently of each other H, D, a C 1 -C 25 alkyl group, or a C 6 -C 14 aryl group, which can optionally be substituted by one, or more groups selected from a C 1 -C 25 alkyl group, a C 1 -C 25 alkoxy group and a C 6 -C 10 aryloxy group;
provided that all of conditions (i) to (iii) are satisfied:
(i) at least one donor group of formula (Xa) or (Xd) is present in the compound of formula (I);
(ii) if Y 2 and Y 4 each represents C 6 arylene, then X 1 is NR 15 , (C═O), C(R 16 )(R 17 ), B(R 18 ), or Si(R 19 )(R 20 ), wherein R 16 , R 17 , R 19 , and R 20 are not methyl and R 15 is not methyl or a C 6 -C 14 aryl group; and
(iii) the compound of Formula (I) is not represented by compound (A-1), (A-2), (A-5), (A-6), (A-8), (B-1), (B-2), (B-5), (B-6), or (B-8):
2 . The compound according to claim 1 , wherein the compound is a compound of any of formula (Ia) to (If)
wherein Y 1 , Y 2 , Y 3 , Y 4 , R 1 , R 2 , R 3 and R 4 are as defined in claim 1 .
3 . The compound according to claim 2 , wherein the compound of formula (I) is a compound of formula (Ia), (Ib), (Ic), (Id), (Ie), or (If), wherein
Y 1 and Y 3 are a direct bond;
R 1 and R 3 are H;
Y 2 and Y 4 are a direct bond, or a group of formula
R 2 and R 4 are independently of each other a donor group of formula (Xa), or (Xd); or
a compound of formula (Ia), (Ib), (Ic), (Id), (Ie), or (If), wherein
Y 2 and Y 4 are a direct bond;
R 2 and R 4 are H;
Y 1 and Y 3 are a direct bond, or a group of formula
R 1 and R 3 are independently of each other a donor group of formula (Xa), or (Xd); or
a compound of formula (Ia), (Ib), (Ic), (Id), (Ie), or (If), wherein
Y 4 is a direct bond, or a group of formula
R 4 is a donor group of formula (Xa), or (Xd);
Y 2 is a group of formula
R 2 is H;
Y 1 and Y 3 are a direct bond;
R 1 and R 3 are H; or
a compound of formula (Ia), (Ib), (Ic), (Id), (Ie), or (If), wherein
Y 1 is a direct bond, or a group of formula
R 1 is a donor group of formula (Xa), or (Xd);
Y 2 , Y 3 and Y 4 are a group of formula
R 2 , R 3 and R 4 are H, wherein
the donor group (Xa) is a group of formula
and
the donor group (Xd) is a group of formula
4 . The compound according to claim 1 wherein Y 1 , Y 2 , Y 3 and Y 4 are independently of each other a direct bond, or a group of formula
5 . The compound according to claim 1 , wherein
R 1 , R 2 , R 3 and R 4 are independently of each other H, a C 1 -C 25 alkyl group, a C 1 -C 25 alkoxy group, a C 6 -C 10 aryloxy group, a donor group of formula
X 1 is O, S, C(O), N(R 15 ), or C(R 16 )(R 17 ); and
R 10 , R 11 , R 21 and R 21′ are independently of each other H, or a C 1 -C 25 alkyl group;
R 15 is a group of formula
R 16 and R 17 are independently of each other H, a C 1 -C 25 alkyl group;
R 22 and R 23 are independently of each other H, a C 1 -C 25 alkyl group, a C 1 -C 25 alkoxy group, or a C 6 -C 10 aryloxy group;
with the proviso that at least one of R 1 , R 2 , R 3 and R 4 is a donor group of formula (Xa) or (Xd).
6 . The compound according to claim 5 , wherein the donor group is a donor group of formula (Xa), wherein X 1 is O, S, C(CH 3 )(CH 3 ), C(═O),
or a donor group of formula (Xd), wherein R 21 and R 21′ are H.
7 . The compound according to claim 1 , wherein the donor group is a group of formula
8 . The compound according to claim 1 , wherein the compound exhibits delayed fluorescence emission.
9 . The compound according to claim 1 , wherein X is NR 9 .
10 . A light-emitting layer comprising the compound according to claim 1 .
11 . An organic light emitting element, comprising the compound of formula (I) according to claim 1 .
12 . The organic light-emitting element according to claim 11 , comprising a light-emitting layer, wherein the light-emitting layer comprises a host material and a guest material, wherein the guest material comprises the compound of formula (I).
13 . The organic light-emitting element according to claim 11 , comprising a light-emitting layer, wherein the light-emitting layer comprises a host material and a guest material, wherein the host material comprises the compound of formula (I).
14 . The organic light-emitting element according to claim 11 , wherein the organic light-emitting element emits delayed fluorescence.
15 . A device selected from the group consisting of a electrophotographic photoreceptor, photoelectric converter, sensor, dye laser, solar cell device and organic light emitting element, wherein the device comprises a compound according to claim 1 .
16 . An organic light emitting element comprising a compound of formula (I); and
an organic compound having a higher value of at least one of excited singlet energy and excited triplet energy than the compound of formula (I);
wherein
X is independently in each occurrence O, S or NR 9 ,
Y 1 , Y 2 , Y 3 and Y 4 are independently of each other a direct bond, or a group of formula -[A 1 ]-[A 2 ] y -, wherein
A 1 and A 2 are independently of each other —CH═CH—, —C≡C— or a C 6 -C 10 arylene group, which may optionally be substituted by one or more C 1 -C 25 alkyl groups; y is 0, or 1;
R 1 , R 2 , R 3 and R 4 are independently of each other H, D, F, Cl, a C 1 -C 25 alkyl group, a C 1 -C 25 alkoxy group, a C 6 -C 10 aryloxy group, or a donor group of formula
X 1 is O, S, N(R 15 ), C(═O), C(R 16 )(R 17 ), B(R 18 ), or Si(R 19 )(R 20 ),
R 9 is H, a C 1 -C 25 alkyl group, or a C 6 -C 10 aryl group;
R 10 , R 11 , R 21 and R 21′ are independently of each other H, D, F, Cl, or a C 1 -C 25 alkyl group;
R 15 , R 16 , R 17 , R 18 , R 19 and R 20 are independently of each other H, D, a C 1 -C 25 alkyl group, or a C 6 -C 14 aryl group, which can optionally be substituted by one, or more groups selected from a C 1 -C 25 alkyl group, a C 1 -C 25 alkoxy group and a C 6 -C 10 aryloxy group;
provided that all of conditions (i) to (iii) are satisfied:
(i) at least one donor group of formula (Xa) or (Xd) is present in the compound of formula (I);
(ii) if Y 2 and Y 4 each represents C 6 arylene, then X 1 is NR 15 , (C═O), C(R 16 )(R 17 ), B(R 18 ), or Si(R 19 )(R 20 ), wherein R 16 , R 17 , R 19 , and R 20 are not methyl and R 15 is not methyl or a C 6 -C 14 aryl group; and
(iii) the compound of Formula (I) is not represented by compound (A-1), (A-2), (A-5), (A-6), (A-8), (B-1), (B-2), (B-5), (B-6), or (B-8):
17 . The organic light emitting element according to claim 16 , wherein the organic compound has a higher excited triplet energy than the compound of formula (I).
18 . The organic light emitting element according to claim 16 , wherein the compound of formula (I) and the organic compound having a higher value of at least one of excited singlet energy and excited triplet energy than the compound of formula (I) are each present in a light-emitting layer.