Organic electro-luminescent element and bioinstrumentation device
An organic EL element having a luminescence peak in a near-infrared range comprises a positive electrode, a negative electrode, and at least one organic layer including a luminescent layer located between the positive electrode and the negative electrode. The luminescent layer comprises a host material, a delayed fluorescent material and a luminescent material. The LUMO and HOMO energy levels of the delayed fluorescent material and the luminescent material, the absorption spectrum of the luminescent material, and the emission spectrum of the delayed fluorescent material satisfy predetermined relationships.
1. An organic electro-luminescent element having a luminescence peak in a near-infrared range, comprising a positive electrode, a negative electrode, and at least one organic layer including a luminescent layer located between the positive electrode and the negative electrode,
wherein the luminescent layer comprises a host material, a delayed fluorescent material, and a luminescent material, and
wherein the delayed fluorescent material and the luminescent material satisfy relationships (1) to (4) shown below:
ΔHOMO+ΔLUMO≤0.6 eV (1);
|ΔHOMO|≤0.4 eV (2);
|ΔLUMO|≤0.4 eV (3); and
| P Abs −P Em |≤30 nm (4),
wherein “ΔHOMO” represents a value of a highest occupied molecular orbital (HOMO) energy level of the luminescent material minus a HOMO energy level of the delayed fluorescent material, wherein “ΔLUMO” represents a value of a lowest unoccupied molecular orbital (LUMO) energy level of the delayed fluorescent material minus a LUMO energy level of the luminescent material, wherein P Abs represents a maximal value at the longest wavelength side of an absorption spectrum of the luminescent material, and wherein P Em represents a maximal value at the longest wavelength side of an emission spectrum of the delayed fluorescent material.
2. The organic electro-luminescent element according to claim 1 , wherein ΔHOMO+ΔLUMO in the relationship (1) is 0.5 eV or less.
3. The organic electro-luminescent element according to claim 1 , wherein ΔHOMO+ΔLUMO in the relationship (1) is 0.4 eV or less.
4. The organic electro-luminescent element according to claim 1 , wherein the absolute value of ΔHOMO in the relationship (2) is 0.3 eV or less.
5. The organic electro-luminescent element according to claim 1 , wherein the absolute value of ΔLUMO in the relationship (3) is 0.3 eV or less.
6. The organic electro-luminescent element according to claim 1 , wherein the absolute value of P Abs −P Em in the relationship (4) is 25 nm or less.
7. The organic electro-luminescent element according to claim 1 , wherein the absolute value of P Abs −P Em in the relationship (4) is 20 nm or less.
8. The organic electro-luminescent element according to claim 1 , wherein the absolute value of P Abs −P Em in the relationship (4) is 0.15 nm or less.
9. The organic electro-luminescent element according to claim 1 , wherein the luminescence peak appears in the near-infrared range including wavelengths between 700 nm and 800 nm.
10. The organic electro-luminescent element according to claim 1 , wherein the luminescent layer comprises a smaller amount of the delayed fluorescent material as compared to an amount of the host material contained in the luminescent layer.
11. The organic electro-luminescent element according to claim 1 , wherein the luminescent layer comprises a smaller amount of the luminescent material as compared to an amount of the host material contained in the luminescent layer.
12. The organic electro-luminescent element according to claim 1 , wherein the luminescent layer comprises an amount of the host material that is 15 wt % to 99.9 wt % with respect to a total amount of the host material, the delayed fluorescent material and the luminescent material contained in the luminescent layer.
13. The organic electro-luminescent element according to claim 1 , wherein the luminescent layer comprises an amount of the delayed fluorescent material that is 5.0 wt % to 50 wt % with respect to a total amount of the host material, the delayed fluorescent material and the luminescent material contained in the luminescent layer.
14. The organic electro-luminescent element according to claim 1 , wherein the luminescent layer comprises an amount of the luminescent material that is 0.1 wt % to 5.0 wt % with respect to a total amount of the host material, the delayed fluorescent material and the luminescent material contained in the luminescent layer.
15. The organic electro-luminescent element according to claim 1 , wherein the luminescent layer comprises an amount of the host material that is 50 wt % to 90 wt %, an amount of the delayed fluorescent material that is 5.0 wt % to 45 wt %, and an amount of the luminescent material that is 0.1 wt % to 5.0 wt %, with respect to a total amount of the host material, the delayed fluorescent material and the luminescent material contained in the luminescent layer.
16. A bioinstrumentation device comprising the organic electro-luminescent element according to claim 1 and a photo detector.
17. An organic electro-luminescent element having a luminescence peak in a near-infrared range, comprising a positive electrode, a negative electrode, and at least one organic layer including a luminescent layer located between the positive electrode and the negative electrode,
wherein the luminescent layer comprises a host material, a delayed fluorescent material, and a luminescent material, and
wherein the delayed fluorescent material and the luminescent material satisfy relationships (1) to (4) shown below:
ΔHOMO+ΔLUMO≤0.6 eV (1);
|ΔHOMO|≤0.4 eV (2);
|ΔLUMO|≤0.4 eV (3); and
| P Abs −P Em |≤30 nm (4),
wherein “ΔHOMO” represents a value of a highest occupied molecular orbital (HOMO) energy level of the luminescent material minus a HOMO energy level of the delayed fluorescent material, wherein “ΔLUMO” represents a value of a lowest unoccupied molecular orbital (LUMO) energy level of the delayed fluorescent material minus a LUMO energy level of the luminescent material, wherein P Abs represents a maximal value at the longest wavelength side of an absorption spectrum of the luminescent material, and wherein P Em represents a maximal value at the longest wavelength side of an emission spectrum of the delayed fluorescent material.
18. The organic electro-luminescent element according to claim 17 , wherein the host material comprises CBP, wherein the delayed fluorescent material comprises TPA-DCPP, and wherein the luminescent material comprises TPA-ThQ.
19. The organic electro-luminescent element according to claim 17 , wherein the luminescent layer is formed at an approximate mass ratio of CBP:TPA-DCPP:TPA-ThQ=75:24:1.
20. A bioinstrumentation device comprising the organic electro-luminescent element according to claim 17 and a photo detector.