Organic light emitting display device

An organic light emitting display device, comprising:

• an anode;
• a cathode;
• a first light emitting part between the anode and the cathode, the first light emitting part having a first light emitting layer;
• and
• a second light emitting part between the cathode and the first light emitting part, the second light emitting part having a second light emitting layer and a third light emitting layer between the second light emitting layer and the cathode,
• wherein the second light emitting layer includes a hole-type host and a first electron-type host, and the third light emitting layer includes the first electron-type host and a second electron-type host, and
• wherein an electron mobility of the first electron-type host is lower than an electron mobility of the second electron-type host.

An organic light emitting display device, comprising:

• an anode;
• a first hole transport layer over the anode;
• a first light emitting layer over the first hole transport layer;
• a first electron transport layer over the first light emitting layer;
• a charge generation layer over the first electron transport layer, the charge generation layer defining a PN-junction therein;
• a second hole transport layer over the charge generation layer;
• a second light emitting layer over the second hole transport layer;
• a third light emitting layer over the second light emitting layer;
• a second electron transport layer over the third light emitting layer;
• and
• a cathode over the second electron transport layer,
• wherein the second light emitting layer includes a hole-type host and a first electron-type host, and the third light emitting layer includes the first electron-type host and a second electron-type host, and
• wherein an electron mobility of the first electron-type host is lower than an electron mobility of the second electron-type host.