Organic electroluminescent device comprising electrontransport layer and electron buffer layer

1. An organic electroluminescent device comprising a first electrode, a second electrode facing the first electrode, a light-emitting layer between the first electrode and the second electrode, and an electron transport layer and an electron buffer layer between the light-emitting layer and the second electrode, wherein the electron buffer layer comprises at least one of the compound represented by the following formula 1 and the compound represented by the following formula 2, and the electron transport layer comprises a compound represented by the following formula 2:

wherein

Y 1 to Y 3 , each independently, represent N or CR 4 , with a proviso that at least two of Y 1 to Y 3 represent N, and

R 1 to R 4 , each independently, represent hydrogen, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C60)aryl, or a substituted or unsubstituted (3- to 60-membered)heteroaryl, or R 4 may be linked to one of R 1 to R 3 to form a substituted or unsubstituted, mono- or polycyclic, (C3-C30) alicyclic or aromatic ring, or the combination thereof, whose carbon atom(s) may be replaced with at least one heteroatom selected from nitrogen, oxygen, and sulfur, wherein R 1 to R 3 not linked with R 4 have the above definition, with a proviso that all of R 1 to R 3 are not hydrogen;

wherein

L 1 represents a substituted or unsubstituted (C6-C30)arylene,

L 2 represents a single bond, or a substituted or unsubstituted (C6-C30)arylene,

A 1 represents a substituted or unsubstituted (3- to 30-membered)heteroaryl, and

the heteroaryl contains at least one heteroatom selected from B, N, O, S, Si, and P.

2. The organic electroluminescent device according to claim 1 , wherein formula 1 is represented by any one of the following formulas 3 to 5:

wherein

Y 1 represents N or CR 4 ,

R 1 , R 2 and R 4 , each independently, represent hydrogen, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl, or R 4 may be linked to R 1 or R 2 to form a substituted or unsubstituted, mono- or polycyclic, (C3-C30) alicyclic or aromatic ring, or the combination thereof, whose carbon atom(s) may be replaced with at least one heteroatom selected from nitrogen, oxygen, and sulfur, wherein R 1 and R 2 not linked with R 4 have the above definition,

L 3 represents a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to 30-membered)heteroarylene,

Z 1 represents O, S, NR 7 or CR 8 C 9 ,

any one of Z 2 and Z 3 represents ═N— or ═CR 10 —, the other of Z 2 and Z 3 represents O, S, NR 11 CR 12 R 13 ,

Ar 1 to Ar 8 , R 5 , and R 7 to R 13 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a carboxyl, a nitro, a hydroxyl, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (3- to 30-membered)heteroaryl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C3-C30)cycloalkenyl, —NR 14 R 15 or SiR 16 R 17 R 18 , or may be linked to an adjacent substituent to form a substituted or unsubstituted, mono- or polycyclic, (C3-C30) alicyclic or aromatic ring, or the combination thereof, whose carbon atom(s) may be replaced with at least one heteroatom selected from nitrogen, oxygen, and sulfur,

R 14 to R 15 , each independently, represent hydrogen, deuterium, a halogen, a cyano, a carboxyl, a nitro, a hydroxyl, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C3-C30)cycloalkyl, a substituted or unsubstituted (C3-C30)cycloalkenyl, a substituted or unsubstituted (3- to 7-membered)heterocycloalkyl, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl,

a, b, and e, each independently, represent an integer of 1 to 4; c, d and f, each independently, represent an integer of 1 to 3; g and h, each independently, represent 1 or 2; where if a to h, each independently, are an integer of 2 or more, each of Ar 1 to Ar 8 may be the same or different, and

the heteroaryl(ene) contains at least one heteroatom selected from B, N, O, S, Si, and P.

3. The organic electroluminescent device according to claim 1 , wherein formula 2 is represented by the following formula 9:

wherein

L 2 represents a single bond, or a substituted or unsubstituted (C6-C30)arylene, and

A 1 represents any one of the following formula 10 or 11:

wherein

*represents a bonding site with L 2 of formula 9,

Y 4 represents N or CR 19 ,

M represents O or S,

A 2 to A 4 , R 19 and Ar 17 , each independently, represent hydrogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to 30-membered)heteroaryl,

q represents an integer of 1 to 4, and

the heteroaryl contains at least one heteroatom selected from B, N, O, S, Si, and P.

4. The organic electroluminescent device according to claim 1 , wherein the substituents of the substituted alkyl, the substituted aryl(ene), the substituted heteroaryl, and the substituted mono- or polycyclic, alicyclic or aromatic ring, or the combination thereof, in R 1 to R 4 , L 1 , L 2 and A 1 , each independently, are at least one selected from the group consisting of deuterium, a halogen, a cyano, a carboxyl, a nitro, a hydroxyl, a (C1-C30)alkyl, a halo(C1-C30)alkyl, a (C2-C30)alkenyl, a (C2-C30)alkynyl, a (C1-C30)alkoxy, a (C1-C30)alkylthio, a (C3-C30)cycloalkyl, a (C3-C30)cycloalkenyl, a (3- to 7-membered)heterocycloalkyl, a (C6-C30)aryloxy, a (C6-C30)arylthio, a (C6-C30)aryl, a (5- to 30-membered)heteroaryl unsubstituted or substituted with a (C1-C30)alkyl or a (C6-C30)aryl, a tri(C1-C30)alkylsilyl, a tri(C6-C30)arylsilyl, a di(C1-C30)alkyl(C6-C30)arylsilyl, a (C1-C30)alkyldi(C6-C30)arylsilyl, an amino, a mono- or di- (C1-C30)alkylamino, a mono- or di-(C6-C30)arylamino, a (C1-C30)alkyl(C6-C30)arylamino, a (C1-C30)alkylcarbonyl, a (C1-C30)alkoxycarbonyl, a (C6-C30)arylcarbonyl, a di(C6-C30)arylboronyl, a di(C1-C30)alkylboronyl, a (C1-C30)alkyl(C6-C30)arylboronyl, a (C6-C30)aryl(C1-C30)alkyl, and a (C1-C30)alkyl(C6-C30)aryl.

5. The organic electroluminescent device according to claim 1 , wherein the compound represented by formula 1 is selected from the group consisting of:

6. The organic electroluminescent device according to claim 1 , wherein the compound represented by formula 2 is selected from the group consisting of:

7. The organic electroluminescent device according to claim 1 , wherein the light-emitting layer comprises a host compound and a dopant compound, the LUMO (lowest unoccupied molecular orbital) energy level of the electron buffer layer is higher than that of the host compound, and the LUMO energy level of the electron transport layer is higher than that of the electron buffer layer, with a proviso that the comparisons of the energy levels are based on absolute values.

8. The organic electroluminescent device according to claim 1 , wherein the LUMO energy level of the electron transport layer (Ae) and the LUMO energy level of the host (Ah) satisfy the following equation:

Ae≤Ah+ 0.5 eV

with a proviso that the comparison of the energy levels is based on absolute values.

9. The organic electroluminescent device according to claim 1 , wherein the LUMO energy level of the electron transport layer (Ae) and the LUMO energy level of the electron buffer layer (Ab) satisfy the following equation:

Ae≤Ab± 0.2 eV

with a proviso that the comparison of the energy levels is based on absolute values.

10. A display system comprising the organic electroluminescent device according to claim 1 .