Light-emitting element, light-emitting device, authentication device, and electronic apparatus
To provide a light-emitting element which emits light in a near-infrared range and has high efficiency and long life, and a light-emitting device, an authentication device, and an electronic apparatus, each of which includes this light-emitting element. A light-emitting element 1 of the invention includes an anode 3 , a cathode 8 , a light-emitting layer 5 which is provided between the anode 3 and the cathode 8 and emits light in a wavelength range of 700 nm or more by applying a current between the anode 3 and the cathode 8 , and an electron transport layer 6 which is provided between the light-emitting layer 5 and the cathode 8 , and includes a first electron transport layer 6 b located on the cathode 8 side and a second electron transport layer 6 a located on the light-emitting layer 5 side, wherein the first electron transport layer 6 b contains a first anthracene-based compound, which has an anthracene skeleton and a nitrogen-containing heterocyclic skeleton, and has an average thickness of less than 8 nm, and the second electron transport layer 6 a contains a second anthracene-based compound, which has an anthracene skeleton but does not have a heterocyclic skeleton.
1. A light-emitting element, comprising:
an anode;
a cathode;
a light-emitting layer which is provided between the anode and the cathode and emits light in a wavelength range of 700 nm or more by applying a current between the anode and the cathode;
an electron transport layer which is provided between the light-emitting layer and the cathode, and includes a first electron transport layer located on the cathode side and a second electron transport layer located on the light-emitting layer side; and
a hole injection layer provided between the light-emitting layer and the anode,
wherein the first electron transport layer contains a first anthracene-based compound, which has an anthracene skeleton and a nitrogen-containing heterocyclic skeleton, and has an average thickness of less than 8 nm,
the second electron transport layer contains a second anthracene-based compound, which has an anthracene skeleton but does not have a heterocyclic skeleton, and
the hole injection layer is constituted by including a material having a hole injection property and at least one of the first anthracene-based compound and the second anthracene-based compound.
2. The light-emitting element according to claim 1 , wherein the electron mobility of the second anthracene-based compound is larger than the electron mobility of the first anthracene-based compound.
3. The light-emitting element according to claim 1 , wherein the average thickness of the second electron transport layer is 25 nm or more and 200 nm or less.
4. The light-emitting element according to claim 1 , wherein
the light-emitting layer is constituted by including a light-emitting material and a host material which holds the light-emitting material, and
the light-emitting material, the host material, the first anthracene-based compound, and the second anthracene-based compound each have a glass transition temperature of 125° C. or higher.
5. The light-emitting element according to claim 1 , wherein the light-emitting element is used by applying a current between the anode and the cathode at a current density of 500 A/cm 2 or more and 1000 A/cm 2 or less.
6. A light-emitting device, comprising the light-emitting element according to claim 1 .
7. An authentication device, comprising the light-emitting element according to claim 1 .
8. An electronic apparatus, comprising the light-emitting element according to claim 1 .