Organic light emitting display device

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 first charge generation layer over the first electron transport layer, the first charge generation layer defining a PN-junction therein;
• a second hole transport layer over the first 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,
• wherein an electron mobility of the first electron-type host is lower than an electron mobility of the second electron-type host,
• wherein the electron mobility of the first electron-type host is equal to or lower than 1×10−5 cm2/Vs, and the electron mobility of the second electron-type host is within a range from 1×10−5 cm2/Vs to 1×10−4 cm2/Vs,
• wherein a LUMO (lowest unoccupied molecular orbital) level of the second electron-type host is lower than a LUMO level of the first electron-type host,
• wherein a difference in the LUMO levels between the first electron-type host and the second electron-type host is equal to or less than 0.5 eV,
• wherein the LUMO level of the first electron-type host is within a range of −2.3 eV to −2.5 eV and the LUMO level of the second electron-type host is within a range of −2.6 eV to −2.8 eV, and
• wherein a HOMO (highest occupied molecular orbital) level of each of the first electron-type host and the second electron-type host is within a range of −5.4 eV to −5.8 eV.