Organic electroluminescence element, illumination device, and display device
An organic electroluminescence element includes: an anode; a cathode; and a luminous layer. The luminous layer includes: a luminescent dopant having a reorganization energy of 0 eV to 0.7 eV in electron transition from a ground state (S 0 ) to a lowest excited triplet state (T 1 ); and a host compound having a reorganization energy of 0 eV to 0.3 eV in electron transfer reaction between a ground state (S 0 ) and an anionic radical state (AR), and having a molecular weight within a range of 500 to 3000.
1. An organic electroluminescence element comprising:
an anode;
a cathode; and
a luminous layer, wherein
the luminous layer includes:
a luminescent dopant having a reorganization energy of 0 eV to 0.7 eV in electron transition from a ground state (S 0 ) to a lowest excited triplet state (T 1 ); and
a host compound having a reorganization energy of 0 eV to 0.3 eV in electron transfer reaction between a ground state (S 0 ) and an anionic radical state (AR), and having a molecular weight within a range of 500 to 3000,
wherein the host compound is represented by one of Formula (1-A), Formula (1-B), Formula (2-A), Formula (3-A), Formula (3-B), and Formula (3-C):
where, in Formula (1-A), R 1 , R 2 , R 4 to R 7 , R 9 to R 17 , and Rb to Re each represent a hydrogen atom, an alkyl group or an aromatic group, and R 8 represents a hydrogen atom; X 1 represents an oxygen atom, a sulfur atom, or NRx; and Rx represents a hydrogen atom or a substituent group,
in Formula (1-B), R 1 , R 2 , R 4 to R 7 , R 9 , R 10 , R 21 to R 28 , and Rb to Re each represent a hydrogen atom, an alkyl group or an aromatic group, at least one of R 7 and R 9 is a substituent group, and R 8 represents a hydrogen atom,
in Formula (2-A), R 1 , R 3 to R 7 , R 9 to R 17 , and Rb to Re each represent a hydrogen atom, an alkyl group or an aromatic group; R 8 represents a hydrogen atom; and X 1 has the same definition as X 1 in Formula (1-A),
in Formula (3-A), R 1 , R 3 to R 7 , R 9 to R 14 , R 16 , R 17 , R 31 to R 38 , and Rb to Re each represent a hydrogen atom or a substituent group; R 8 represents a hydrogen atom; and X 1 has the same definition as X 1 in Formula (1-A),
in Formula (3-B), R 1 , R 3 to R 7 , R 9 to R 14 , R 16 , R 17 , R 41 to R 47 , and Rb to Re each represent a hydrogen atom or a substituent group; R 8 represents a hydrogen atom; and X and X 1 have the same definition as X 1 in Formula (1-A), and
in Formula (3-C), R 1 , R 3 to R 7 , R 9 to R 14 , R 16 to R 18 , R 31 to R 37 , and Rb to Re each represent a hydrogen atom or a substituent group; R 8 represents a hydrogen atom; and X 1 has the same definition as X 1 in Formula (1-A).
2. The organic electroluminescence element of claim 1 , wherein the luminescent dopant has the reorganization energy of 0 eV to 0.5 eV in the electron transition from the ground state (S 0 ) to the lowest excited triplet state (T 1 ).
3. The organic electroluminescence element of claim 1 , wherein the host compound has the reorganization energy of 0 eV to 0.15 eV in the electron transfer reaction between the ground state (S 0 ) and the anionic radical state (AR).
4. The organic electroluminescence element of claim 1 , wherein the luminescent dopant has the reorganization energy of 0 eV to 0.5 eV in the electron transition from the ground state (S 0 ) to the lowest excited triplet state (T 1 ).
5. The organic electroluminescence element of claim 1 , wherein the luminescent dopant is a phosphorescent compound.
6. The organic electroluminescence element of claim 5 , wherein the phosphorescent compound is represented by Formula (A1):
where R represents a substituent group; Z represents a nonmetallic atomic group necessary for formation of a five- to seven-member ring; n1 represents an integer of 0 to 5; B 1 to B 5 each represent a carbon atom, CRa, a nitrogen atom, NRb, an oxygen atom, or a sulfur atom, with the proviso that at least one of B 1 to B 5 represents a nitrogen atom; Ra and Rb each represent a hydrogen atom or a substituent group; B 1 to B 5 are five atoms forming an aromatic nitrogen-containing heterocycle; B 5 and Z may be bonded to each other to form a ring; M 1 represents a metal belonging to any one of Groups 8 to 10 in the periodic table; X 1 and X 2 each represent a carbon atom, a nitrogen atom, or an oxygen atom; L 1 represents an atomic group forming a bidentate ligand together with X 1 and X 2 ; and m1 represents an integer of 1 to 3 and m2 represents an integer of 0 to 2, with the proviso that m1+m2 is 2 or 3.
7. The organic electroluminescence element of claim 1 , wherein the luminous layer is formed with a coating solution.
8. The organic electroluminescence element of claim 1 , wherein the luminous layer emits white light.
9. An illumination device comprising the organic electroluminescence element of claim 1 .
10. A display device comprising the organic electroluminescence element of claim 1 .