Two-stage micro-cavity full-color Micro-OLED device structure

Abstract

The invention discloses a two-stage micro-cavity full-color Micro-OLED device structure, relates to the field of micro display, and particularly relates to a two-stage micro-cavity display structure. The structure of the device is composed of the first-stage electroluminescence microcavity and the second-stage electroluminescence microcavity, green light generated by the first-stage electroluminescence microcavity excites a light conversion layer in the second-stage electroluminescence microcavity, color conversion is achieved through the second-stage electroluminescence microcavity, the light emitting efficiency is improved, red, green and blue full-color display is achieved, and the display effect is good. The problems that in an existing full-color Micro-OLED device display, the efficiency of adding a color filter to a white light device is low, and the service life is short are solved.

Description

Technical Field

[0001] This invention relates to the field of microdisplays, and more particularly to a two-stage microcavity display structure. Technical Background

[0002] Since the sub-pixel size in silicon-based OLED micro full-color displays is typically only a few micrometers, it is difficult to achieve high pixel density through vacuum mask evaporation. Therefore, a white OLED combined with a color filter is usually used to achieve full-color display. In this scheme, the filter only allows specific wavelengths to be emitted to the outside, that is, only one of the three colors of white light (red, green, and blue) can be emitted, resulting in a large amount of photon waste and affecting device efficiency and lifespan.

[0003] In existing technologies, blue light excitation downconversion layers are also used to achieve full-color displays. However, the poor working stability of blue light materials seriously hinders the improvement of the lifespan of electroluminescent devices. At the same time, the conversion efficiency is limited due to the presence of only a single electroluminescent microcavity. Summary of the Invention

[0004] The purpose of this invention is to provide a two-stage microcavity full-color Micro-OLED device structure that can improve display efficiency and lifespan.

[0005] A two-stage microcavity full-color Micro-OLED device structure includes a substrate, characterized in that a total reflection electrode layer, an organic light-emitting layer, a primary microcavity layer, a light conversion layer, a secondary microcavity layer, and an external coupling layer are disposed on the substrate in sequence; in: The reflective electrode layer, the organic light-emitting layer, and the primary microcavity layer form an electroluminescent microcavity, which forms a green organic light-emitting device with a peak wavelength of 490-550nm for emitting green light. The primary microcavity layer, the light conversion layer, and the secondary microcavity layer form a photoluminescent microcavity.

[0006] The primary and secondary microcavity layers are made of aluminum, magnesium, titanium, copper, chromium, silver, or ytterbium and their alloys. The thickness of the primary microcavity layer is 10-30 nm, and the thickness of the secondary microcavity layer is 5-25 nm.

[0007] The thickness of the primary microcavity layer affects the optical and electrical performance of the device, while the secondary microcavity layer affects the optical performance of the device.

[0008] The photoluminescent microcavity uses a conversion layer to convert green light into red, green, and blue light respectively, and uses the microcavity to enhance wavelength resonance, thereby improving the color purity and conversion efficiency of the device and thus improving the device efficiency.

[0009] The thickness of the primary microcavity layer must not be less than 10 nm. Reducing the thickness will prevent the formation of a continuous thin film in the primary microcavity layer, affecting the conductivity and electroluminescence performance. At the same time, it must not be more than 30 nm. Increasing the thickness will result in insufficient optical transmittance, affecting the number of photons entering the conversion layer and causing a decrease in efficiency.

[0010] The thickness of the secondary microcavity layer should be lower than that of the primary microcavity layer to ensure that the number of photons emitted to the outside after conversion of the photoluminescent microcavity is higher than the number of photons reflected back to the inside.

[0011] The light conversion layer includes a blue light conversion layer, a green light conversion layer, and a red light conversion layer; the green light emitted by the green light organic light emission device combines with the blue light conversion layer to form blue photonic pixels, combines with the green light conversion layer to form green photonic pixels, and combines with the red light downconversion layer to form red photonic pixels.

[0012] The light conversion layer is composed of photoresist mixed with rare earth materials, organic materials, quantum dot materials, or perovskite materials.

[0013] Optionally, the photoresist is a fluorinated photopolymer to reduce damage to the underlying organic layer.

[0014] The outer coupling layer further improves the light extraction efficiency.

[0015] In this invention, a high-efficiency, long-life green light-emitting device is used. The green light generated by the primary electroluminescent microcavity excites the light conversion layer in the secondary photoluminescent microcavity. The conversion layer converts the green light into red, green and blue light respectively. The secondary photoluminescent microcavity is used to realize the three-color emission and enhance the light extraction efficiency, so as to realize the red, green and blue full-color display. This solves the problems of low efficiency and short life of white light devices with color filters in existing full-color Micro-OLED device displays, and poor working stability when using blue light materials. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the device structure in Embodiment 1 of the present invention.

[0018] Figure 2 This is a spectral diagram of the red, green, and blue sub-pixels in Embodiment 1 of the present invention.

[0019] Figure 3 This is a schematic diagram of the device structure in Embodiment 2 of the present invention.

[0020] The structure includes a silicon substrate 20, a total reflection electrode layer 30, an organic light-emitting layer 40, a primary microcavity layer 50, a light conversion layer 60, a secondary microcavity layer 70, an external coupling layer 80, a light conversion layer 60, a blue light conversion layer 61, a green light conversion layer 62, a red light conversion layer 63, a blue sub-pixel 101, a green sub-pixel 102, and a red sub-pixel 103. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: Refer to Figure 1 As shown, the two-stage microcavity full-color Micro-OLED device structure is as follows: a total reflection electrode layer 30 with an array pattern is prepared on a silicon substrate 20; a green organic light-emitting layer 40 and a first-stage microcavity layer 50 are sequentially deposited by vacuum evaporation equipment; a light conversion layer 60 is prepared, including a blue light conversion layer 61, a green light conversion layer 62 and a red light conversion layer 63 of the same thickness; and then a second-stage microcavity layer 70 and an external coupling layer 80 are prepared.

[0023] The total reflection electrode layer 30, the green light organic layer 40, and the first-level microcavity layer 50 constitute a green light organic light emission device with an emission wavelength of 532nm. The green light emitted by the green light organic light emission device passes through the blue light conversion layer 61, the green light conversion layer 62, and the red light conversion layer 63 to form blue, green, and red light emission. Under the action of the second-level microcavity layer 70, the spectrum is further narrowed, and the color purity and light emission efficiency are improved by utilizing the microcavity effect.

[0024] The device in this embodiment has a first-stage microcavity layer thickness of 20 nm and a second-stage microcavity layer thickness of 15 nm, with an external quantum efficiency of 13.6%.

[0025] The thickness of the primary microcavity layer affects the optical and electrical performance of the device.

[0026] Comparative Example 1: A two-stage microcavity full-color Micro-OLED device structure, with a first-stage microcavity layer thickness of 20nm and a second-stage microcavity layer thickness of 25nm. Other technical contents are the same as in Example 1, and its external quantum efficiency is 9.3%.

[0027] Comparative Example 2: Two-stage microcavity full-color Micro-OLED device structure, the thickness of the first-stage microcavity layer is 20nm, the thickness of the second-stage microcavity layer is 2nm, and other technical contents are the same as in Example 1. Its external quantum efficiency is 8.2%.

[0028] Comparative Example 3: Two-stage microcavity full-color Micro-OLED device structure, the thickness of the first-stage microcavity layer is 10nm, and other technical contents are the same as in Example 1. The second-stage microcavity layer is 15nm, and the external quantum efficiency is 10.3%.

[0029] Comparative Example 4: The thickness of the first-level microcavity layer is 30 nm, the thickness of the second-level microcavity layer is 15 nm, and other technical contents are the same as those in Example 1. Its external quantum efficiency is 8.7%.

[0030] Example 2: Figure 2 As shown, the blue light conversion layer 61, the green light conversion layer 62, and the red light conversion layer 63 have different thicknesses. The thickness of the blue light conversion layer is less than that of the green light conversion layer, and the thickness of the green light conversion layer is less than that of the red light conversion layer, which ensures wavelength resonance and improves luminous efficiency and lifespan.

[0031] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Two-stage microcavity full-color Micro-OLED device structure, comprising a substrate, characterized in that The substrate is provided with, in sequence, a total reflection electrode layer, an organic light-emitting layer, a primary microcavity layer, a light conversion layer, a secondary microcavity layer and an external coupling layer; Wherein: The reflection electrode layer, the organic light-emitting layer and the primary microcavity layer form an electroluminescent microcavity, forming a green light organic light-emitting device that emits green light with a peak wavelength of 490-550 nm; The primary microcavity layer, the light conversion layer and the secondary microcavity layer form a photoluminescent microcavity.

2. The two-stage microcavity full-color Micro-OLED device structure according to claim 1, wherein The primary microcavity layer and the secondary microcavity layer are made of aluminum, magnesium, titanium, copper, chromium, silver or ytterbium or alloys thereof.

3. The two-stage microcavity full-color Micro-OLED device structure according to claim 1, wherein The primary microcavity layer has a thickness of 10-30 nm, and the secondary microcavity layer has a thickness of 5-25 nm.

4. The two-stage microcavity full-color Micro-OLED device structure according to claim 1, wherein The light conversion layer comprises a blue light conversion layer, a green light conversion layer and a red light conversion layer; the green light emitted by the green light organic light-emitting device combines with the blue light conversion layer to form a blue light sub-pixel, combines with the green light conversion layer to form a green light sub-pixel, and combines with the red light conversion layer to form a red light sub-pixel.

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