Light-emitting device having tandem structure

A light-emitting device comprising:

• a first electrode;
• a second electrode;
• and
• an organic compound layer,
• wherein the organic compound layer is positioned between the first electrode and the second electrode,
• wherein the organic compound layer comprises a first light-emitting unit, a second light-emitting unit, and an intermediate layer,
• wherein the intermediate layer is positioned between the first light-emitting unit and the second light-emitting unit,
• wherein the first light-emitting unit is positioned between the first electrode and the intermediate layer,
• wherein the first light-emitting unit comprises a first light-emitting layer and a first electron-transport layer,
• wherein the first electron-transport layer is in contact with the intermediate layer,
• wherein the intermediate layer is configured to block holes moving from the first electrode side to the second electrode side and comprises an organic compound having basicity with an acid dissociation constant pKa of 8 or more, and
• wherein a highest occupied molecular orbital (HOMO) level of an organic compound having the highest HOMO level among organic compounds included in the first electron-transport layer is greater than or equal to −5.90 eV and less than or equal to −5.00 eV.

A light-emitting device comprising:

• a first electrode;
• a second electrode;
• and
• an organic compound layer,
• wherein the organic compound layer is positioned between the first electrode and the second electrode,
• wherein the organic compound layer comprises a first light-emitting unit, a second light-emitting unit, and an intermediate layer,
• wherein the intermediate layer is positioned between the first light-emitting unit and the second light-emitting unit,
• wherein the first light-emitting unit is positioned between the first electrode and the intermediate layer,
• wherein the first light-emitting unit comprises a first light-emitting layer and a first electron-transport layer,
• wherein the first electron-transport layer is in contact with the intermediate layer,
• wherein the intermediate layer comprises an organic compound having basicity with an acid dissociation constant pKa of 8 or more, and
• wherein a highest occupied molecular orbital (HOMO) level of an organic compound having the highest HOMO level among organic compounds included in the first electron-transport layer is greater than or equal to −5.90 eV and less than or equal to −5.00 eV.