Organic light emitting device

An organic light emitting device, comprising:

• an anode;
• a hole transport region on the anode;
• an emission layer on the hole transport region;
• an electron transport region on the emission layer;
• and
• a cathode on the electron transport region,
• wherein the hole transport region comprises:
• a first hole transport material represented by the following Formula 1 or Formula 2;
• and
• a second hole transport material represented by the following Formula 3 or Formula 4:
• wherein, in Formulae 1, 2, 3 and 4,
• Ar1, Ar2, Ar3, Ar4, Ar5, and Ar8 are each independently a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 30 ring carbon atoms, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted silyl group, a halogen atom, a deuterium atom, or a hydrogen atom,
• Ar6 and Ar7 are each independently a substituted aryl group having 6 to 30 ring carbon atoms, an unsubstituted aryl group having 10 to 30 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 30 ring carbon atoms, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted silyl group, a halogen atom, a deuterium atom, or a hydrogen atom, provided that, in Ar6 and Ar7, a substituent of the substituted aryl group having 6 to 30 ring carbon atoms, the substituted heteroaryl group having 5 to 30 ring carbon atoms, the substituted alkyl group having 1 to 20 carbon atoms, and the substituted silyl group does not include an amino group, and provided that neither Ar6 nor Ar7 are a substituted fluorenyl group,
• X is a direct linkage or CR14R15,
• R1 to R15 are each independently a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 30 ring carbon atoms, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted silyl group, a halogen atom, a deuterium atom, or a hydrogen atom,
• R5 is a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 30 ring carbon atoms, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted silyl group, a halogen atom, a deuterium atom, or a hydrogen atom, provided that, in R5, a substituent of the substituted aryl group having 6 to 30 ring carbon atoms, the substituted heteroaryl group having 5 to 30 ring carbon atoms, the substituted alkyl group having 1 to 20 carbon atoms, and the substituted silyl group does not include an amino group,
• L1 and L2 are each independently a direct linkage, a substituted or unsubstituted alkyl group having 6 to 30 carbon atoms, a substituted or unsubstituted arylene group having 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 30 ring carbon atoms,
• a, b, and c are each independently an integer of 0 to 4,
• d is an integer of 0 to 3, and
• e is an integer of 0 to 5,
• in the case where e is an integer of 2 to 5, adjacent ones of R1 to R15 are separate or are bound to form a ring,
• wherein the emission layer comprises a thermally activated delayed fluorescence material.