Organic light emitting device

An organic light-emitting device, comprising:

• a substrate;
• a first electrode;
• a second electrode facing the first electrode;
• an emission layer between the first electrode and the second electrode;
• a first electron transport layer between the second electrode and the emission layer, the first electron transport layer including a first electron transporting material;
• a second electron transport layer between the second electrode and the first electron transport layer, the second electron transport layer including a second electron transporting material;
• a third electron transport layer between the second electrode and the second electron transport layer, the third electron transport layer including a third electron transporting material and a fourth electron transporting material;
• and
• a hole transport layer between the first electrode and the emission layer,
• wherein:
• the first electron transporting material has an electron mobility smaller than an electron mobility of the second electron transporting material at an electric field of 800 to 1000 V/cm,
• the second electron transporting material and the third electron transporting material each independently have an electron mobility of about 10−8 to about 10−3 cm2/V·s at an electric field of 800 to 1000 V/cm, and
• the third electron transport layer has an electron injection barrier of about 0.2 eV or less at an interface between the third electron transport layer and the second electrode.