White light electroluminescent device

Abstract

The invention pertains to the field of optoelectronic devices, and discloses a white light electroluminescent device. The device has a layered structure. The layered structure sequentially includes: a substrate / an electrically conductive layer / a hole injection layer / a hole transporting layer / an electron barrier layer / a first blue light emitting layer / a first barrier layer / a red light emitting phosphor layer / a spacer layer / a green light emitting phosphor layer / a second barrier layer / a second blue light emitting layer / a hole barrier layer / an electron transporting layer / an electron injection layer / a cathode layer. The materials of the first and second blue light emitting layers both are a hole transporting material doped with a blue light emitting material, and the materials of the red light emitting phosphor layer and the green light emitting phosphor layer are a beryllium complex material doped with a red light emitting phosphor material and a beryllium complex material doped with a green light emitting phosphor material respectively. According to the white light electroluminescent device of the invention, the first and second barrier layers are respectively arranged between the first blue light emitting layer and the red light emitting phosphor layer, and between the second blue light emitting layer and the green light emitting phosphor layer, so triplet excitons of the blue light emitting material can be diffused into the red light emitting phosphor layer and the green light emitting phosphor layer to undergo radiative transition so as to emit light, so that light emitting efficiency of the device is further improved.

Description

technical field [0001] The invention relates to the field of optoelectronic devices, in particular to a white light electroluminescence device. Background technique [0002] In 1987, C.W.Tang and Van Slyke of Eastman Kodak Company in the United States reported a breakthrough in the research of organic electroluminescence. A high-brightness, high-efficiency double-layer organic electroluminescent device (OLED) was prepared by using ultra-thin film technology. In this double-layer structure device, the brightness reaches 1000cd / m at 10V 2 , its luminous efficiency is 1.51lm / W, and its lifespan is more than 100 hours. [0003] The principle of OLED light emission is based on the action of an external electric field, electrons are injected from the cathode to the lowest unoccupied molecular orbital (LUMO) of organic matter, and holes are injected from the anode to the highest occupied orbital (HOMO) of organic matter. Electrons and holes meet, recombine, and form excitons in ...

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Problems solved by technology

[0004] Luminescent materials are the most important factor affecting luminous efficiency. Luminescent materials can be divided into fluorescent materials (ie, blue light materials) and phosphorescent materials (ie, red light phosphorescent materials and / or green light phosphorescent materials). Fluorescent materials are blocked due to triplet transitions. Therefore, it can only emit light through the radiation inactivation of the singlet state, and the ratio of the triplet excitons to the singlet excitons is about 3:1; and since only 25wt% of the excitons in the fluorescent material can be effectively used, the remaining 75wt % are all through non-radiative attenuation, the energy is released in the form of heat, which increases the temperature of the device, thereby reducing the life of the device, while the phosphorescent material is due to the strong spin coupling effect of the metal atom itself, so the original impossible three-line Therefore, the luminous efficiency is greatly improved. At present, the luminous efficiency of green phosphorescent materials and red phosphorescent materials is relatively good, and the material stability is high, while the life and stability of blue phosphorescent materials are not very good, which restricts blue light glow

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