Organic light-emitting device

An organic light-emitting device, comprising:

• an anode;
• a cathode;
• and
• an organic layer between the anode and the cathode, the organic layer including:
• an emission layer (EML), the EML including a first host and a second host,
• a hole transport region between the anode and the EML, the hole transport region including at least one of a hole injection layer (HIL), a hole transport layer (HTL), a buffer layer, or an electron blocking layer (EBL),
• an electron transport region between the EML and the cathode, the electron transport region including at least one of a hole blocking layer (HBL), an electron transport layer (ETL), or an electron injection layer (EIL), and
• an intermediate layer between the EML and the electron transport region;
• wherein an electron affinity of a compound of the intermediate layer [EAintermediate layer] and an electron affinity of the first host [EAhost1] satisfy a relationship represented by the following expression:
• EAintermediate layer≧EAhost1+0.3 eV.