A top-emitting OLED device

Abstract

A top-emitting OLED device, comprising a substrate and a first electrode layer, a hole injection layer, a hole transport layer, a light emitting layer, at least four electron transport sublayers, a second electrode layer, and a light output layer sequentially formed on the substrate A coupling layer; wherein, the electron transport layer includes a plurality of electron transport sublayers with different refractive indices. The electron transport sublayer arrangement includes two schemes: one is that the refractive index of the electron transport sublayer gradually decreases along the direction away from the light-emitting layer, and the other is that the electron transport sublayer includes organic electron transport sublayers and inorganic electron transport sublayers arranged at intervals. electron transport sublayer. Both solutions can increase light transmittance, weaken wide-angle interference, reduce microcavity effect, and solve the technical problem of poor luminous properties of devices at large viewing angles, and are especially suitable for the field of flat panel displays.

Description

technical field [0001] The invention relates to the field of organic electroluminescence. In particular, it relates to a top-emitting OLED device with improved luminous properties at large viewing angles. Background technique [0002] Organic Light Emitting Diode (OLED) is a device that uses organic materials as the light-emitting layer under the action of an electric field. It is a new type of active light-emitting display device with light weight, thin thickness, high brightness, and viewing angle Wide, fast response, high luminous efficiency, no need for backlighting, and flexible display, etc., have important applications in the field of display and lighting, especially as the display device with the most potential to replace liquid crystal displays. According to the light-emitting position of the device, it can be divided into bottom emitting OLED (Bottom Emitting OLED, referred to as BEOLED) and top emitting OLED (TopEmitting OLED, referred to as TEOLED). [0003] Th...

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Problems solved by technology

The microcavity effect has the functions of selecting, narrowing and strengthening the light source. It is often used to improve the chromaticity of the device, enhance the emission intensity of a specific wavelength, and change the luminous color of the device. However, the existence of wide-angle interference will affect the viewing angle of the device. Characteristics, that is, with the shift of the viewing angle, the luminous peak shifts, resulting in brightness differences and chromaticity drift, etc., especially at large viewing angles, the optical properties are not good, and the chromatic aberration is more serious

[0005] The current solution to improve the viewing angle characteristics of top-emitting OLEDs is generally to add a light output coupling layer on the semi-transparent cathode, such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, etc. Organic substances with high refractive index and low absorptivity, or evaporate a layer of high refractive index dielectric ZnSe, ZnS, etc. on the surface of the semi-transparent cathode as a coupling layer to improve the transmittance and light export rate, but the above-mentioned scheme has a wide-angle effect on top-emitting OLEDs. The suppression of interference phenomena is limited, and the viewing angle characteristics have not been significantly improved

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