Tandem white organic light emitting device

A tandem white organic light emitting device comprising:

• a first electrode and a second electrode opposite to each other;
• a charge generation layer consisting of an n-type charge generation layer and a p-type charge generation layer stacked between the first electrode and the second electrode;
• a first stack disposed between the first electrode and the n-type charge generation layer and comprising a first hole transport layer, a first light emitting layer emitting blue light, and a first electron transport layer;
• and
• a second stack disposed between the p-type charge generation layer and the second electrode and comprising a second hole transport layer directly contacting the p-type charge generation layer and having a single layer structure, a second light emitting layer doped with a phosphorescent dopant to emit light with a longer wavelength than that of blue light, and a second electron transport layer,
• wherein the p-type charge generation layer is formed of organic materials only, and at least one organic material contained in the p-type charge generation layer has a LUMO level of −6.0 eV to −4.5 eV,
• wherein the second hole transport layer has a HOMO level different from the LUMO level of the at least one organic material contained in the p-type charge generation layer by 0.5 eV or less.