Organic electroluminescent device comprising dopant material and plurality of host materials

[0150] Example 1-1: Preparation of an organic electroluminescent device containing the material combination of the present invention.

[0151] First, the glass substrate, which has an 80nm thick indium tin oxide (ITO) anode, is cleaned, and then treated with UV ozone and oxygen plasma. After processing, the substrate is dried in a glove box filled with nitrogen to remove moisture, and then the substrate is mounted on the substrate holder and loaded into the vacuum chamber. The organic layer specified below, the vacuum degree is about 10 -8 In the case of Torr, vapor deposition is sequentially performed on the ITO anode through thermal vacuum at a rate of 0.2-2 angstroms/sec. The compound HI is used as a hole injection layer (HIL) with a thickness of 100 angstroms. The compound HT is used as a hole transport layer (HTL) with a thickness of 350 angstroms. Compound H-25 is used as an electron blocking layer (EBL) with a thickness of 50 angstroms. Then compound D-174 is doped in the first host compound H-25 and the second host compound E-1 to be co-deposited as the light emitting layer (EML), the total thickness is 400 angstroms, the weight of compound H-25 and compound E-1 The ratio is 1:1, and the dopant compound D-174 accounts for 10% of the total weight of the light-emitting layer. The compound Host 1 was used as the hole blocking layer (HBL) with a thickness of 100 angstroms. On the HBL, compound ET and 8-hydroxyquinoline-lithium (Liq) are co-deposited as an electron transport layer (ETL), where Liq accounts for 60% of the total weight of the ETL layer, and the total thickness of the ETL layer is 350 angstroms. Finally, Liq was vapor-deposited with a thickness of 10 angstroms as an electron injection layer (EIL), and 120-nm aluminum was vapor-deposited as a cathode. The device was then transferred back to the glove box and sealed with a glass lid to complete the device.

[0152] Comparative Examples 1-1 to 1-3: The preparation method is the same as that of Example 1-1, except that the host material of the light-emitting layer of Comparative Examples 1-1 to 1-3 in Table 1 is used, and the host material is The weight ratio of the dopant is adjusted to 80:20, which is the best ratio of the single-component host to the weight ratio of the dopant used.

[0153] Comparative Examples 1-4 to 1-6: The preparation method is the same as that of Example 1-1, except that the host materials of the light-emitting layer of Comparative Examples 1-4 to 1-6 in Table 1 are used.

[0154] The detailed device layer structure and thickness are shown in Table 1. For layers with more than one kind of materials, different compounds are doped in the weight ratios described.

[0155] Table 1

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[0157]

[0158] The structure of some materials used in the device is as follows:

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[0161] Table 2 lists the test results of Example 1-1 and Comparative Example 1-1 to Comparative Example 1-6. The color coordinates, peak wavelength and half-width in Table 2 are measured at a brightness of 1000 nits, and the voltage, external quantum efficiency, and current efficiency are measured at a current density of 15mA/cm 2 Measured below, the lifetime is the time required for the initial luminance of 10,000 nits to decay to 95% of the initial luminance.

[0162] Table 2

[0163]

[0164] Table 2 shows the test results of electroluminescent devices with different host materials and dopant D-174. It can be seen from the table that the color coordinates of Example 1-1 are (0.338, 0.632), the peak wavelength is 527nm, the half-value width is 58.3nm, 15m A/cm 2 The voltage is 4.19V, the external quantum efficiency is 21.87%, the current efficiency is 84cd/A, and the life of the LT95 is 1260 hours at 10000 nits. The performance parameters of Comparative Example 1-1 are inferior to those of Example 1-1, and the spectral red shift, especially the life of LT95 is only 21 hours, which is far less than that of Example 1-1. Although Comparative Example 1-2 has a half-value width of only 56.4 nm, which is slightly narrower than Example 1-1, and the voltage is the same as Example 1-1, the external quantum efficiency, current efficiency, and LT95 lifetime are not as good as those of Example 1-1. Although the voltage of Comparative Example 1-3 is only 4.03V, the spectrum is red-shifted compared with Example 1-1, and the external quantum efficiency, current efficiency, and LT95 lifetime are not as good as those of Example 1-1. The peak wavelength and half width of Comparative Example 1-4 are close to those of Example 1-1, but the voltage is as high as 5.24V, which is more than 1V higher than that of Example 1-1, and the external quantum efficiency, current efficiency, and LT95 lifetime are still low In Example 1-1. The spectrum of Comparative Example 1-5 is slightly blue-shifted from that of Example 1-1, and the half-value width is slightly narrower to 56.4 nm. The three parameters of voltage, external quantum efficiency, and current efficiency are close to those of Example 1-1, but the lifetime is significantly lower than that of Example 1-1. Example 1-1, the difference is 299 hours. The spectral red shift of Comparative Example 1-6. Although the external quantum efficiency and current efficiency are slightly higher than those of Example 1-1, the voltage is as high as 4.63V, which exceeds the voltage of Example 1-1 by 0.44V, and the LT95 lifetime is only 182 hours. It is much shorter than the lifetime of Example 1-1. These results indicate that the use of the light-emitting layer material combination disclosed in the present invention can improve the spectrum and significantly improve the overall performance of the device, such as lowering the voltage, improving efficiency and life.