Organic electroluminescent device having an exciton quenching layer

1. An organic electroluminescent device comprising:

(A) an anode layer A;

(B) a light-emitting layer B comprising at least one host material H B and at least one emitter E B , wherein the light-emitting layer B does not comprise more than 20% by weight of an electron transport material ETM D ;

(C) an exciton quenching layer C comprising at least one emitter E C and at least 80% by weight of at least one electron transport material ETM D ;

(D) an electron-transport layer D comprising at least one electron transport material ETM D ; and

(E) a cathode layer K,

wherein the layers are arranged in the sequential order in the following order (A)-(B)-(C)-(D)-(E), wherein optionally one or more additional layers may be present between the anode layer A and the light-emitting layer B, between electron-transport layer D and the cathode layer K, or each between the anode layer A and the light-emitting layer B and between electron-transport layer D and the cathode layer K, and

wherein the exciton quenching layer C is adjacent to both the light-emitting layer B and the electron-transport layer D.

2. The organic electroluminescent device according to claim 1 , wherein said organic electroluminescent device is a device selected from the group consisting of an organic light emitting diode, a light emitting electrochemical cell, and a light-emitting transistor.

3. The organic electroluminescent device according to claim 1 , wherein the at least one emitter compound E B is a thermally activated delayed fluorescence (TADF) emitter.

4. The organic electroluminescent device according to claim 1 , wherein the at least one emitter compound E C is a fluorescence emitter.

5. The organic electroluminescent device according to claim 1 , wherein the exciton quenching layer C comprises:

(i) 90-99.95% by weight of the at least one electron transport material ETM D ;

(ii) 0.05-10% by weight of the at least one emitter compound E C .

6. The organic electroluminescent device according to claim 1 , wherein the light-emitting layer B comprises:

(i) 5-99% by weight of at least one host compound H B ;

(ii) 1-50% by weight of at least one emitter compound E B ; and optionally

(iii) 0-94% by weight of one or more further host compounds H B2 differing from H B ; and optionally

(iv) 0-94 by weight of one or more solvents.

7. The organic electroluminescent device according to claim 1 , wherein the electron-transport layer D comprises more than 89.9% by weight, referred to the electron transporting components, of at least one electron transport material ETM D .

8. The organic electroluminescent device according to claim 1 , wherein the at least one emitter compound E B exhibits an emission with an emission maximum λ max (E B ) and a full width at half maximum FWHM(E B ) and the at least one emitter compound E C exhibits an emission with an emission maximum λ max (E C ) and a full width at half maximum FWHM(E C ), wherein

λ max ( E B )≧λ max ( E C ).

9. The organic electroluminescent device according to claim 8 , wherein

λ max ( E B )≧λ max ( E C )≧[λ max ( E B )−FWHM( E B )].

10. The organic electroluminescent device according to claim 9 , wherein

λ max ( E B )≧λ max ( E C )≧[λ max ( E B )−FWHM( E B )/2].

11. The organic electroluminescent device according to claim 1 , wherein the at least one emitter compound E C has a lowest unoccupied molecular orbital LUMO(E C ) having an energy E LUMO (E C ) and the at least one electron transport material ETM D has a lowest unoccupied molecular orbital LUMO(ETM D ) having an energy E LUMO (ETM D ), wherein

E LUMO ( E C )≧ E LUMO (ETM D ).

12. The organic electroluminescent device according to claim 11 , wherein

E LUMO ( E C )− E LUMO (ETM D )≦0.3 eV.

13. The organic electroluminescent device according to claim 1 , wherein the at least one emitter compound E C has a highest occupied molecular orbital HOMO(E C ) having an energy E HOMO (E C ) and the at least one electron transport material ETM D has a highest occupied molecular orbital HOMO(ETM D ) having an energy E HOMO (ETM D ), wherein

E HOMO ( E C )≧ E HOMO (ETM D ).

14. The organic electroluminescent device according to claim 1 , wherein the at least one emitter compound E C has a highest occupied molecular orbital HOMO(E C ) having an energy E HOMO (E C ) and the at least one emitter compound E B has a highest occupied molecular orbital HOMO(E B ) having an energy E HOMO (E B ), wherein

E HOMO ( E C )≧ E HOMO ( E B ).

15. The organic electroluminescent device according to claim 1 , wherein the at least one emitter compound E C has a lowest excited singlet state energy level S1(E C ) and the at least one electron transport material ETM D has a lowest excited singlet state energy level S1(ETM D ), wherein

S 1(ETM D )≧ S 1( E C ).

16. The organic electroluminescent device according to claim 1 , wherein the at least one emitter compound E C has a lowest excited triplet state energy level T1(E C ) and has a lowest excited singlet state energy level S1(E C ) and the at least one electron transport material ETM D has a lowest excited triplet state energy level T1(ETM D ), wherein

T 1(ETM D )≧ T 1( E C ),

and

S 1( E C )> T 1( E C )≧ S 1( E C )/2.

17. The organic electroluminescent device according to claim 1 , wherein the at least one electron transport material ETM D is NBPhen.

18. The organic electroluminescent device according to claim 1 , wherein the light-emitting layer B has a thickness d B and the exciton quenching layer C has a thickness d C and wherein d B >d C .

19. The organic electroluminescent device according claim 18 , wherein the light-emitting layer B has a thickness d B between 5 and 180 nm and the exciton quenching layer C has a thickness d C between 0.5 and 4 nm.