Light-emitting element and light-emitting device
A light-emitting element includes a first electrode, a second electrode, a first light-emitting layer and a second light-emitting layer provided between the first electrode and the second electrode and including the same quantum dots, and an intermediate layer provided between the first light-emitting layer and the second light-emitting layer.
1 . A light-emitting element comprising:
a first electrode;
a second electrode;
a first light-emitting layer and a second light-emitting layer both of which provided between the first electrode and the second electrode, both of the first light-emitting layer and the second light-emitting layer including quantum dots being the same as each other; and
an intermediate layer provided between the first light-emitting layer and the second light-emitting layer,
wherein the intermediate layer has an ionization potential larger than an ionization potential of each of the first light-emitting layer and the second light-emitting layer.
2 . The light-emitting element according to claim 1 ,
wherein the intermediate layer further has an electron affinity smaller than an electron affinity of each of the first light-emitting layer and the second light-emitting layer.
3 . The light-emitting element according to claim 1 ,
wherein the intermediate layer includes at least one selected from the group consisting of Al 2 O 3 , SiO 2 , MgO, ZrO 2 , HfO 2 , Cr 2 O 3 , Ga 2 O 3 , Ta 2 O 5 , LiF, BaF 2 , CaF 2 , MgF 2 , NaF, NaCl, CdF 2 , CdCl 2 , CdBr 2 , CdI 2 , ZnF 2 , ZnCl 2 , ZnBr 2 , and ZnI 2 , and
the first light-emitting layer and the second light-emitting layer further include at least one selected from the group consisting of a Group II-VI semiconductor compound, a Group III-V semiconductor compound, and a Group IV semiconductor compound.
4 . The light-emitting element according to claim 3 ,
wherein the Group II-VI semiconductor compound includes at least one selected from the group consisting of MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, Bas, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, and HgTe,
the Group III-V semiconductor compound includes at least one selected from the group consisting of GaAs, GaP, GaN, InN, InAs, InP, and InSb, and
the Group IV semiconductor compound includes at least one selected from the group consisting of Si and Ge.
5 . The light-emitting element according to claim 1 ,
wherein a film thickness of the intermediate layer has a value in a range of 0.5 nm or more and 20 nm or less.
6 . The light-emitting element according to claim 1 ,
wherein the intermediate layer is formed of an inorganic material including a metal oxide or a metal halide.
7 . The light-emitting element according to claim 1 ,
wherein the first light-emitting layer is disposed closer to the first electrode than the second light-emitting layer is,
the light-emitting element further comprising:
a first charge transport layer provided between the first electrode and the first light-emitting layer, the first charge transport layer including an inorganic oxide semiconductor, and
a second charge transport layer provided between the second electrode and the second light-emitting layer, the second charge transport layer including another inorganic oxide semiconductor.
8 . The light-emitting element according to claim 1 ,
wherein a film thickness of each of the first light-emitting layer and the second light-emitting layer is 10 nm or more.
9 . The light-emitting element according to claim 1 ,
wherein magnitudes of the ionization potential and an electron affinity of the first light-emitting layer are equal to magnitudes of the ionization potential and an electron affinity of the second light-emitting layer, respectively.
10 . A light-emitting device comprising:
a thin film transistor; and
the light-emitting element according to claim 1 electrically connected to the thin film transistor.
11 . A light-emitting element comprising:
a first electrode;
a second electrode;
a first light-emitting layer and a second light-emitting layer both of which provided between the first electrode and the second electrode, both of the first light-emitting layer and the second light-emitting layer including quantum dots being the same as each other; and
an intermediate layer provided between the first light-emitting layer and the second light-emitting layer,
wherein the intermediate layer is formed of a material not causing quenching of the quantum dots included in each of the first light-emitting layer and the second light-emitting layer.
12 . The light-emitting element according to claim 11 ,
wherein the intermediate layer is configured to suppress a conduction of charge between the first light-emitting layer and the second light-emitting layer.
13 . The light-emitting element according to claim 11 ,
wherein a film thickness of the intermediate layer has a value in a range of 0.5 nm or more and 20 nm or less.
14 . A light-emitting device comprising:
a thin film transistor; and
the light-emitting element according to claim 11 electrically connected to the thin film transistor.
15 . A light-emitting element comprising:
a first electrode;
a second electrode;
a first light-emitting layer and a second light-emitting layer both of which provided between the first electrode and the second electrode, both of the first light-emitting layer and the second light-emitting layer including quantum dots being the same as each other; and
an intermediate layer provided between the first light-emitting layer and the second light-emitting layer,
wherein the first light-emitting layer and the second light-emitting layer are formed of a same material.
16 . The light-emitting element according to claim 15 , further comprising:
a third light-emitting layer provided between the first light-emitting layer and the second light-emitting layer, the third light-emitting layer including quantum dots being the same as the quantum dots of the first light-emitting layer and the second light-emitting layer,
wherein the intermediate layer includes:
a first intermediate layer provided between the first light-emitting layer and the third light-emitting layer, and
a second intermediate layer provided between the third light-emitting layer and the second light-emitting layer.
17 . The light-emitting element according to claim 16 ,
wherein the first electrode is an anode, and the second electrode is a cathode,
the first light-emitting layer, the third light-emitting layer, and the second light-emitting layer are layered in this stated order from the first electrode toward the second electrode,
the first intermediate layer has an electron affinity smaller than an electron affinity of each of the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer, and
the second intermediate layer has an ionization potential larger than an ionization potential of each of the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer.
18 . The light-emitting element according to claim 17 ,
wherein the electron affinity and an ionization potential of the first intermediate layer are smaller than an electron affinity and the ionization potential of the second intermediate layer, respectively.
19 . The light-emitting element according to claim 15 ,
wherein the intermediate layer is configured to suppress a conduction of charge between the first light-emitting layer and the second light-emitting layer.
20 . A light-emitting device comprising:
a thin film transistor; and
the light-emitting element according to claim 15 electrically connected to the thin film transistor.