Light-Emitting Device

A light-emitting element comprising:

• an anode;
• a cathode;
• a light-emitting layer between the anode and the cathode;
• and
• a first layer between the anode and the light-emitting layer,
• wherein the light-emitting layer comprises:
• a phosphorescent compound;
• a first organic compound having an electron-transport property;
• and
• a second organic compound having a hole-transport property,
• wherein the first layer comprises a third organic compound which is an aromatic amine compound or a carbazole derivative, and a fourth organic compound,
• wherein the first organic compound and the second organic compound form an exciplex,
• wherein the fourth organic compound comprises at least one of a cyano group, a fluoro group, and a chloro group,
• wherein an emission spectrum of the exciplex overlaps with an absorption band in the longest wavelength side of the phosphorescent compound, and
• wherein a highest occupied molecular orbital level of the second organic compound is lower than a highest occupied molecular orbital level of the phosphorescent compound by 0.1 eV or more.

A light-emitting element comprising:

• an anode;
• a cathode;
• a light-emitting layer between the anode and the cathode;
• and
• a first layer between the anode and the light-emitting layer,
• wherein the light-emitting layer comprises:
• a phosphorescent compound;
• a first organic compound having an electron-transport property;
• and
• a second organic compound having a hole-transport property,
• wherein the first layer comprises a third organic compound which is an aromatic amine compound or a carbazole derivative, and a fourth organic compound,
• wherein the first organic compound and the second organic compound form an exciplex,
• wherein the fourth organic compound comprises at least one of a cyano group, a fluoro group, and a chloro group,
• wherein an emission spectrum of the exciplex overlaps with an absorption band in the longest wavelength side of the phosphorescent compound,
• wherein an energy difference between a triplet excited state and a ground state of the first organic compound is higher than an energy difference between a triplet excited state and a ground state of the phosphorescent compound by 0.15 eV or more, and
• wherein an energy difference between a triplet excited state and a ground state of the second organic compound is higher than the energy difference between the triplet excited state and the ground state of the phosphorescent compound by 0.15 eV or more.

A light-emitting element comprising:

• an anode;
• a cathode;
• a light-emitting layer between the anode and the cathode;
• and
• a hole-injection layer between the anode and the light-emitting layer and in contact with the anode,
• wherein the light-emitting layer comprises:
• a phosphorescent compound;
• a first organic compound having an electron-transport property;
• and
• a second organic compound having a hole-transport property,
• wherein the hole-injection layer comprises a third organic compound which is an aromatic amine compound or a carbazole derivative, and a fourth organic compound,
• wherein the first organic compound and the second organic compound form an exciplex,
• wherein the fourth organic compound comprises at least one of a cyano group, a fluoro group, and a chloro group,
• wherein an emission spectrum of the exciplex overlaps with an absorption band in the longest wavelength side of the phosphorescent compound, and
• wherein a highest occupied molecular orbital level of the second organic compound is lower than a highest occupied molecular orbital level of the phosphorescent compound by 0.1 eV or more.