Organic electroluminescent device

1. An organic electroluminescent device, comprising:

a plurality of kinds of light-emitting units having different light-emitting wavelengths, the light-emitting units being organic light-emitting diodes, the organic light-emitting diodes comprising a plurality of single-colored organic light-emitting diodes and/or a plurality of white-light organic light-emitting diodes provided with optical filters;

wherein at least one kind of the organic light-emitting diodes has a microcavity structure, a microcavity optical length L i of the organic light-emitting diode having the microcavity structure and a light-emitting wavelength λ i of the corresponding light-emitting unit meet the following formula:

L i =n i λ i

wherein n i ≥2, n i is a positive integer, and the n i corresponds to at least one of the plurality of kinds of light-emitting units having different light-emitting wavelengths, λ i is larger than or equal to 3; m is the number of the kinds of the light-emitting units, m≥i≥1, i and m are positive integers.

2. The organic electroluminescent device according to claim 1 , wherein, m is 3, λ1>λ2>λ3, and n2>n1, n2>n3.

3. The organic electroluminescent device according to claim 2 , wherein, 577 nm≥λ 2 ≥492 nm, and n 2 ≥3.

4. The organic electroluminescent device according to claim 2 , wherein, 760 nm≥λ1≥600 nm, and 480 nm≥λ3≥435 nm.

5. The organic electroluminescent device according to claim 1 , wherein, each of the organic light-emitting diodes comprises a first electrode layer, a light-emitting layer and a second electrode layer stacked one by one, and the microcavity structure is formed between the first electrode layer and the second electrode layer.

6. The organic electroluminescent device according to claim 5 , wherein, thicknesses H i of the light-emitting layers of the organic light-emitting diodes having different light-emitting wavelengths meet the following formula: H 2 >H 1 , H 2 >H 3 .

7. The organic electroluminescent device according to claim 5 , wherein, at least one kind of the organic light-emitting diodes has at least 2 light-emitting layers, two adjacent light-emitting layers having a connection layer provided therebetween.

8. The organic electroluminescent device according to claim 7 , wherein, the connection layer is a transparent layer and comprises a single layer or a multi-layer stacked composite structure formed by one or more materials selected from Li 2 CO 3 , HAT-CN, TAPC, TAPC doped with HAT-CN, Ag and ITO; the connection layer has a thickness of 5 nm-100 nm; the connection layer has a refractive index of 1.6-2.2.

9. The organic electroluminescent device according to claim 5 , wherein, the light-emitting layer of at least one kind of the organic light-emitting diodes contains a thermal activated delayed fluorescent material.

10. The organic electroluminescent device according to claim 9 , wherein, the light-emitting layer comprises a host material and a guest material, the host material comprises two kinds of thermal activated delayed fluorescent materials that form an exciplex, and the guest material is a fluorescent material.

11. The organic electroluminescent device according to claim 10 , wherein, the thermal activated delayed fluorescent materials are selected from 4CzIPN, 2CzPN, 4CzPN, 4CzTPN, 4CzTPN-Me, and 4CzTPN-Ph; and the fluorescent material is selected from Alq3, C545T, DPVBi, and DCJTB.

12. The organic electroluminescent device according to claim 5 , wherein, the microcavity structure of at least one kind of the organic light-emitting diodes is also provided with an optical compensation layer.

13. The organic electroluminescent device according to claim 12 , wherein, the optical compensation layer is at least one selected from a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer and an electron injection layer.

14. The organic electroluminescent device according to claim 5 , wherein, the first electrode layer of at least one kind of the organic light-emitting diodes is a reflective electrode layer, and the second electrode layer of the corresponding organic light-emitting diode is a semi-reflective semi-transparent electrode layer.

15. The organic electroluminescent device according to claim 14 , wherein, not all the thicknesses of the reflective electrode layers of the respective organic light-emitting diodes having different light-emitting wavelengths are the same.

16. The organic electroluminescent device according to claim 15 , wherein, each of the reflective electrode layers comprises a reflective layer and an anode layer stacked on the reflective layer; not all the thicknesses of the anode layers of the organic light-emitting diodes are the same, the reflective layers have the same thickness.

17. The organic electroluminescent device according to claim 16 , wherein, the reflective layer is a metal material layer, and the anode layer is a high work function layer.

18. The organic electroluminescent device according to claim 14 , wherein, the semi-reflective semi-transparent electrode layer comprises at least two layers of metal oxide layer and/or metal layer stacked in sequence.

19. The organic electroluminescent device according to claim 18 , wherein, the metal oxide layer is selected from MoO 3 , WO 3 , and IZO; and the metal layer is selected from Ag and Mg.

20. The organic electroluminescent device according to claim 14 , wherein, the semi-reflective semi-transparent electrode layer has a light transmittance no less than 15%.