Organic electroluminescence device and diamine compound for organic electroluminescence device

An organic electroluminescence device comprising:

• a first electrode;
• a hole transport region disposed on the first electrode;
• an emission layer disposed on the hole transport region;
• an electron transport region disposed on the emission layer;
• and
• a second electrode disposed on the electron transport region,
• wherein the hole transport region comprises a diamine compound represented by Formula 1:
• wherein in Formula 1,
• a1 to a4 are each independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, or a group represented by Formula 2-1,
• one of a1 to a4 is a group represented by Formula 2-1,
• another one of a1 to a4 is a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms,
• a5 to a8 are each independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, or a group represented by Formula 2-2 below,
• one of a5 to a8 is a group represented by Formula 2-2, and
• another one of a5 to a8 is a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms:
• wherein in Formula 2-1 and Formula 2-2,
• L1 and L2 are each independently a direct linkage, a substituted or unsubstituted arylene group having 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted heteroarylene group having 2 to 30 ring-forming carbon atoms,
• m and n are each independently an integer from 0 to 4, and
• Ar1 to Ar4 are each independently a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 30 ring-forming carbon atoms, and
• when a1 is a group represented by Formula 2-1, a5 is a group represented by Formula 2-2, and a7 is a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, then one of a2 to a4 is a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, and at least one of Ar1 to Ar4 is a substituted or unsubstituted heteroaryl group having 2 to 30 ring-forming carbon atoms.