Fluorescent organic light emitting elements having high efficiency

1. A compound of formula I

wherein

X is O,

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(R 16 )(R 17 ), B(R 18 ), or Si(R 19 )(R 20 ),

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;

with the proviso that at least one donor group of formula (Xa), or (Xd) is present in the compound of formula (I); and

with the proviso that when R 2 and R 4 are each a donor group of formula (Xa), at least one of Y 2 and Y 4 is not a C6-C 10 arylene.

2. A device comprising a compound according to claim 1 , wherein the device emits delayed fluorescence.

3. 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

4. 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, N(R 15 ), or C(R 16 )(R 17 ); and

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).

5. The compound according to claim 4 , wherein the donor group is a donor group of formula (Xa), wherein X 1 is O, S, C(CH 3 )(CH 3 ),

or a donor group of formula (Xd), wherein R 21 and R 21′ are H.

6. The compound according to claim 1 , wherein the donor group is a group of formula

7. The compound according to claim 1 , wherein the compound of formula (I) is a compound of formula (Ia)

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); and

with the proviso that when both Y 2 and Y 4 are

at least one of R 2 and R 4 is a donor group of formula (Xd);

or

a compound of formula (Ia), 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) 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) 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

8. A light-emitting layer comprising the compound according to claim 1 .

9. An organic light emitting element, comprising the compound of formula (I) according to claim 1 .

10. The organic light-emitting element according to claim 9 , 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).

11. The organic light-emitting element according to claim 9 , 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).

12. The organic light-emitting element according to claim 9 , wherein the organic light-emitting element emits delayed fluorescence.

13. 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 .