Organic light emitting diode, display device comprising the same and compound

Organic light emitting diode comprising a non-transparent substrate, an anode, a cathode, an emission layer, and an electron transport layer stack;

• wherein
• the electron transport layer stack is arranged between the emission layer and the cathode;
• the electron transport layer stack comprises optionally a first electron transport layer;
• the electron transport layer stack comprises a second electron transport layer;
• the second electron transport layer consists of a compound of formula (II)
• n is 1 or 2;
• m is 1 or 2;
• k is 0, 1 or 2;
• Ar2 is independently selected from the group consisting of substituted or unsubstituted C2 to C42 heteroaryl and substituted or unsubstituted C6 to C60 aryl;
• Z is independently selected from substituted or unsubstituted C6 to C30 aryl and substituted or unsubstituted C2 to C42 heteroaryl;
• G has the formula (IIa)
• G having the formula (IIa) is bonded at *1 to Z;
• Ra and Rb are independently selected from C2 to C12 alkyl;
• and
• the first electron transport layer and the second electron transport layer are free of an electrical dopant.