CN116634796A - Optical microcavity structure and OLED display panel - Google Patents
Optical microcavity structure and OLED display panel Download PDFInfo
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Abstract
The invention belongs to the technical field of organic light-emitting devices, and discloses an optical microcavity structure and an OLED display panel. One or more microcavity structures exist in the display panel, the light emitting efficiency is greatly improved by the optical microcavity effect, the light emitting wave peak is narrowed, and the display color gamut is larger than 160% of sRGB color gamut. The cholesteric liquid crystal film can simultaneously improve the utilization rate of light emitted by the light-emitting panel from about 42% before the cholesteric liquid crystal film is not increased to more than 90%, and the light-emitting energy consumption can be reduced by more than 45%, which is equivalent to greatly improving the screen brightness on the premise of unchanged light-emitting energy consumption or reducing the energy consumption of the screen under the condition of unchanged screen brightness.
Description
Technical Field
The invention belongs to the technical field of organic light emitting devices, and relates to an optical microcavity structure and an OLED display panel.
Background
Organic light-emitting diodes (OLED) display panels have the advantages of simple structure, self-luminescence without a backlight source, high contrast, thin thickness, wide viewing angle, high reaction speed, applicability to flexible panels, wide application temperature range and the like, and are representative of new-generation flat display technologies and are increasingly promoted by the industry. Due to the vibration sidebands and the non-uniform broadening effect, the spectral half width (FWHM) of the luminescent materials, whether small organic molecules or high molecular polymers, is often greater than 80mm, and thus the use efficiency in color displays prepared by using the synthesis of the three primary colors red, green and blue is very low. To solve this problem, besides in the choice of materials, one prepares Fabry-Perot (F-P) optical microcavities for organic electroluminescence to obtain narrow-band emission of high brightness by changing the structure of the light emitting diode. The optical microcavity not only achieves narrow-band emission, but also greatly enhances the emission intensity relative to a device without a microcavity structure, and can achieve wavelength tunability and color display. The organic electroluminescent diode with microcavity effect has a microcavity selective structure for optical mode, so that narrow-band emission with specific wavelength can be obtained.
Microcavity effect (microcavity effect) refers to the phenomenon that in a micron-scale optical resonator, the wavelength of light is comparable to the size of the resonator, so that the energy density of light is greatly increased. This phenomenon can be observed in gases, liquids, solids and semiconductor materials. Microcavity effects are widely used in optical elements, such as lasers, sensors, electro-optical modulators, etc., which can change the coherence, emission characteristics, transmission speed, and interactions between photons.
Displays based on OLED display panels are widely applied to the display fields of mobile phones, computers, televisions and the like. These displays are typically composed of self-emitting organic diodes, quarter-phase retardation films, and linear polarizers. Since the linear polarizing plate self structure determines that only 50% of light emitted by the diode can be utilized theoretically at most, the rest is absorbed by the polarizing plate, so that the utilization efficiency of light emitted by the light-emitting panel in the display panel is less than 50%. The cathode in the existing top emission type OLED display device is of a semi-transparent and semi-reflective structure, a microcavity effect is formed between the cathode and the anode to strengthen the light-emitting efficiency, but light emitted by the light-emitting panel has different wavelengths, and the dielectric layers with the same thickness cause different microcavity effect intensities of the light with different wavelengths, so that the color cast problem is caused. In the prior art, the microcavity length of light with different wavelengths is adjusted by adjusting and controlling different luminous sub-pixel structures, so that the difficulty in the implementation process is great. Therefore, a new display panel structure is needed to improve the light-emitting efficiency and enhance the display effect.
Disclosure of Invention
The invention provides a microcavity structure and an OLED display panel. By circular polarization dichroism of cholesteric liquid crystals, microcavity structures are formed between the cholesteric liquid crystal film and the reflective layer in the light-emitting panel, wherein the reflective layer can be a cathode, or an anode, or both cathode and anode, or a non-electrode reflective layer in the display panel. By adjusting the sequence of the cholesteric liquid crystal films with different pitch structures inside the cholesteric liquid crystal films, the position sequence of the cholesteric liquid crystal films in the display panel, the thickness of the cholesteric liquid crystal films with different pitch in the cholesteric liquid crystal films, the refractive index of each cholesteric liquid crystal film in the cholesteric liquid crystal films and other parameters, the light emitted by the red, green and blue three-primary-color light emitting sub-pixels in the OLED display panel forms a uniform microcavity effect, the color cast problem caused by the non-uniform microcavity effect of light with different wavelengths is reduced, the light emitting efficiency and the emergent light intensity are improved, and the display color gamut is increased.
In one aspect, the present invention relates to a microcavity structure, schematically shown in FIG. 1. The cholesteric liquid crystal film and the reflecting layer form an optical resonant cavity, and the reflecting layer can be a cathode or an anode of a light-emitting panel or the reflecting layer is simultaneously a cathode and an anode or a reflecting layer with non-electrode function arranged in the light-emitting panel layer in different OLED display panel structures.
The cholesteric liquid crystal film converts the unpolarized light emitted by the light-emitting panel layer into about 50% of left-handed polarized light and about 50% of right-handed polarized light, when the optical selectivity of the cholesteric liquid crystal film allows the left-handed polarized light (right-handed polarized light) to pass through, the part is denoted as Y1, the right-handed polarized light (left-handed polarized light) is reflected back to the reflecting layer of the light-emitting panel, after being reflected again by the reflecting layer, the polarization direction of the circularly polarized light is changed, namely the left-handed polarized light (right-handed polarized light) is changed into right-handed polarized light (left-handed polarized light), the part is denoted as Y2, the circularly polarized light with the changed polarization direction can smoothly pass through the cholesteric liquid crystal film, and the optical path difference of the Y1 and the Y2 circularly polarized light is adjusted to ensure that the optical path difference of the two differs by an integral multiple of the light wavelength, namely Wherein delta is Y1 For the optical path of Y1, delta Y2 For the optical path of Y2, m is a positive integer, n i Represents the refractive index of the ith functional layer, d i For the i-th functional layer thickness, j is the number of all functional layers through which Y2 passes, and λ is the reflection center wavelength. Thereby forming interference constructive of light and improving the light intensity of emergent light. A schematic diagram of the transmission and reflection wavelength bandwidth of the cholesteric liquid crystal film for the full visible band is shown in fig. 11.
In another aspect, the present invention relates to a display panel comprising:
the liquid crystal display comprises a light-emitting panel, a cholesteric liquid crystal film, a phase delay film and a linear polarizing plate, wherein the cholesteric liquid crystal film is arranged on the light-emitting side of the light-emitting panel;
the light-emitting panel at least comprises an anode, an organic light-emitting layer and a cathode; in the top emission type display panel, the cathode light transmittance is between 10% and 100%, preferably, the light transmittance is between 30% and 100%, and the anode reflectance is greater than 90%, preferably, greater than 95%. In the bottom emission type display panel, the anode light transmittance is between 10% and 100%, preferably, the light transmittance is between 30% and 100%, and the cathode reflectance is more than 90%, preferably, more than 95%.
Depending on the position of the cholesteric liquid crystal film in the display panel, the following structure may be used:
in the top emission type display panel structure, the cholesteric liquid crystal film may be disposed on a side of the cathode far from the anode, which is close to the light-emitting side, wherein the cathode may be a transparent electrode or a semi-transparent semi-reflective electrode; the cholesteric liquid crystal film is arranged between the two layers of anodes, wherein the anode close to one side of the substrate is a reflecting electrode, and the electrode far away from the substrate is a transparent or semitransparent electrode; the cholesteric liquid crystal film is arranged between two layers of cathodes, wherein the semi-transparent and semi-reflective electrode is arranged on the side close to the light emitting side, the transparent electrode is arranged on the side close to the light emitting layer, or the semi-transparent and semi-reflective electrodes are arranged on the two layers of cathodes, or the transparent electrodes are arranged on the two layers of cathodes.
In the bottom emission type display panel structure, the cholesteric liquid crystal film may be disposed on the side of the anode far from the cathode, wherein the anode may be a transparent anode or a semi-transparent semi-reflective anode; the cholesteric liquid crystal film is arranged between the two layers of cathodes, wherein the cathode close to one side of the substrate is a reflecting cathode, and the cathode far away from the substrate is a transparent or semitransparent cathode; the cholesteric liquid crystal film is arranged between two layers of anodes, wherein the side close to the light emitting side is a semi-transparent semi-reflective anode, the side close to the light emitting layer is a transparent anode, or the two layers of anodes are semi-transparent semi-reflective electrodes or the two layers of anodes are transparent electrodes.
The display panels with the different structures have microcavity structures formed by the cholesteric liquid crystal film and the reflecting electrode in the light-emitting panel layer.
Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects or advantages:
according to the microcavity structure and the OLED display panel, circular polarization dichroism of cholesteric liquid crystal is utilized, and the microcavity structure is formed between a cholesteric liquid crystal film and a reflecting layer of a light-emitting panel. The microcavity structure in the invention can lead the light emitted by the red, green and blue three-primary-color luminous sub-pixels in the OLED display panel to form a uniform microcavity effect, reduce the color shift problem caused by the microcavity effect of uneven light with different wavelengths, improve the light emitting efficiency and the light intensity of emergent light, and increase the display color gamut.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram showing microcavity effect formed by the cholesteric liquid crystal film 30 and the reflective layer of the light-emitting panel layer 40.
Fig. 2 is a schematic diagram of a top-emission (cholesteric liquid crystal film between a retarder and a transparent cathode) display panel.
Fig. 3 is a schematic diagram of a top-emission (cholesteric liquid crystal film between a retarder and a transflective cathode) display panel.
Fig. 4 is a schematic diagram showing the structure of a top emission type (cholesteric liquid crystal film is located between two cathodes) display panel.
Fig. 5 is a schematic diagram of a 5-layer cholesteric liquid crystal film structure.
Fig. 6 is a schematic diagram of a structure in which 3 layers of cholesteric liquid crystal film are bonded together by optical cement between adjacent layers.
Fig. 7 is a schematic diagram showing the structure of a bottom emission type (cholesteric liquid crystal film between a phase retarder and a transparent anode) display panel.
Fig. 8 is a schematic diagram of a bottom emission type (cholesteric liquid crystal film is located between a phase retarder and a transflective anode) display panel.
Fig. 9 is a schematic diagram showing the structure of a bottom emission type (cholesteric liquid crystal film is located between two layers of anodes) display panel.
Fig. 10 is a schematic diagram showing the structure of a bottom emission type (cholesteric liquid crystal film is located between two cathodes) display panel.
Fig. 11 is a schematic view of a cholesteric liquid crystal film for visible light reflectance and transmittance. The abscissa is wavelength (nm) and the ordinate is in%.
Reference numerals illustrate: 10-linear polarizing plate layer, 20-phase retardation film layer, 30-cholesteric liquid crystal film, 31-first cholesteric liquid crystal film layer, 32-second cholesteric liquid crystal film layer, 33-third cholesteric liquid crystal film layer, 34-fourth cholesteric liquid crystal film layer, 35-fifth cholesteric liquid crystal film layer, 40-light emitting panel layer, 41-reflective anode, 42-light emitting layer, 43-transparent cathode, 44-semi-transparent semi-reflective cathode, 45-reflective cathode, 46-transparent anode, 47-semi-transparent semi-reflective anode, 50-substrate layer, 61-first optical cement, 62-second optical cement, 63-third optical cement, 64-fourth optical cement, 65-fifth optical cement.
Light is the direction of the Light path.
Detailed Description
The following describes the technical aspects of the present invention with reference to examples, but the present invention is not limited to the following examples.
Example 1
Fig. 2 is a schematic structural diagram of an OLED display panel according to an embodiment of the present invention. The embodiment of the invention provides an OLED display panel, which comprises:
a light emitting panel layer 40 including at least an anode layer 41, a light emitting layer 42, and a cathode layer 43;
a cholesteric liquid crystal film 30 disposed on the light-emitting side of the light-emitting panel layer 40, the cholesteric liquid crystal film 30 being configured to convert unpolarized light emitted from the light-emitting panel layer 40 into about 50% of left circularly polarized light and about 50% of right circularly polarized light and allow one to transmit and the other to reflect;
a phase retardation film layer 20 disposed on a side of the cholesteric liquid crystal film 30 away from the light-emitting panel, the phase retardation film 20 serving as a quarter-wave plate for conversion between circularly polarized light and linearly polarized light;
the linear polarizing plate layer 10 is disposed on a side of the phase retardation film layer 20 away from the cholesteric liquid crystal film, and the linear polarizing plate layer 10 absorbs polarized light whose vibration direction is perpendicular to its transmission axis, transmits polarized light parallel to its transmission axis, and converts unpolarized light into linear polarized light after passing through the linear polarizing plate.
In the above structure, the light-emitting panel layer 40 and the cholesteric liquid crystal film 30, the cholesteric liquid crystal film 30 and the phase retardation film layer 20, and the phase retardation film layer 20 and the linear polarizing plate 10 are all adhered together by the optical adhesive layers 61 to 63, and the optical adhesive layers 61 to 63 may have the same refractive index and the same thickness, or may have different refractive indexes and different thicknesses. Preferably, the refractive index of the optical adhesive layer 61 is between the light emitting panel layer 40 and the cholesteric liquid crystal film 30, the refractive index of the optical adhesive layer 62 is between the cholesteric liquid crystal film 30 and the retarder layer 20, and the refractive index of the optical adhesive layer 63 is between the retarder layer 20 and the linear polarizer 10.
The cholesteric liquid crystal film 30 at least comprises a cholesteric liquid crystal having a pitch gradient, and the reflection center wavelength and reflection bandwidth of the cholesteric liquid crystal film 30 having a single pitch are as follows:
λ＝n*P*cosθ
Δλ＝Δn*P*cosθ
in the above formula, lambda is the reflection center wavelength, n is the average refractive index of the cholesteric liquid crystal film, P is the pitch of the cholesteric liquid crystal, delta lambda is the reflection wavelength bandwidth, delta n is the birefringence index of the cholesteric liquid crystal film, and theta is the included angle between the incident angle of light and the helical center axis of the cholesteric liquid crystal.
Cholesteric liquid crystal films having various pitch structures have reflection bandwidths of light waves which are the union of reflection bandwidths of the pitches, that is,
Δλ＝Δn 1 *P 1 *cosθ 1 ∪Δn 2 *P 2 *cosθ 2 ∪Δn 3 *P 3 *cosθ 3 ···∪Δn n *P n *cosθ n
Wherein the birefringence delta n of each pitch structure 1 ，Δn 2 ，Δn 3 ···Δn n May be the same or different.
The polarization state regulation and control of different wavelengths can be realized by adjusting gradient distribution of different pitches of the cholesteric liquid crystal film 30, wherein the gradient distribution of the cholesteric liquid crystal film layers of different pitches in the cholesteric liquid crystal film can be continuous gradient distribution or jump gradient distribution, and the arrangement of the liquid crystal film layers of different pitches in the gradient distribution of the pitches can be in any order without specific limitation. For different light incidence angles theta, the method can be realized by increasing the pitch of cholesteric liquid crystal in the cholesteric liquid crystal film 30 or regulating the inclination angle of the helical axis of the cholesteric liquid crystal in the cholesteric liquid crystal film 30 to the film surface.
As shown in fig. 2, in the structure of an OLED display panel, the cathode in the light-emitting panel layer 40 is made of a transparent material, i.e. the light transmittance is greater than 90%, the anode is a reflective layer, and the visible light reflectance of the anode to the OLED light-emitting panel is greater than 90%. A microcavity structure is formed between the cholesteric liquid crystal film 30 and the reflective anode 41. The cholesteric liquid crystal film 30 converts the unpolarized light emitted from the light emitting panel layer 40 into about 50% of the left-handed polarized light and about 50% of the right-handed polarized light, when the optical selectivity of the cholesteric liquid crystal film 30 allows the left-handed polarized light (right-handed polarized light) to pass through, this part is denoted as Y1, the right-handed polarized light (left-handed polarized light) is reflected back to the anode of the light emitting panel layer 40, after being reflected again by the anode, the polarization direction of the circularly polarized light is changed, i.e., the left-handed polarized light (right-handed polarized light) is changed into right-handed polarized light (left-handed polarized light), this part is denoted as Y2, the circularly polarized light with the changed polarization direction can smoothly pass through the cholesteric liquid crystal film layer 30, and the optical path difference between the circularly polarized light of the functions Y1 and Y2 is adjusted so that the two differ by an integer multiple of the wavelength of light, i.e Wherein delta is Y1 For the optical path of Y1, delta Y2 For the optical path of Y2, m is a positive integer, n i Represents the refractive index of the ith functional layer, d i For the i-th functional layer thickness, j is the number of all functional layers through which Y2 passes, and λ is the reflection center wavelength. Thereby forming interference constructive of light and improving the light intensity of emergent light. Wherein the Y1 light intensity is denoted as I Y1 The Y2 light intensity is denoted as I Y2 Under the condition that the light intensity loss in the Y2 multi-reflection process is not large, record I Y1 ≈I Y2 ，
In the absence of cholesteric liquid crystal films, the OLED display panel emits light at:
in the above, I Y1 +I Y2 The total light intensity of the light emitted by the light-emitting panel is recorded, and the linear polarizing plate only allows the light with the polarization direction parallel to the transmission axis to pass through, so that the light intensity emitted by the OLED display panel is half of the total light intensity of the light emitted by the light-emitting panel under the condition of not considering the absorption of the light by each functional layer.
In the case of adding the cholesteric liquid crystal film 30 without forming the microcavity structure, the emitted light intensity is
I 0 ≈I Y1 +I Y2 ≈2I Y1
By adding the cholesteric liquid crystal film, the emergent light of the OLED display panel is converted into linear polarized light with the vibration direction parallel to the transmission axis of the linear polarizing plate before reaching the linear polarizing plate, and under the condition that the absorption of light by each functional layer is ignored, the light emitted by the light-emitting panel in the OLED display panel can basically reach the view angle side of the display panel.
Under the condition that the cholesteric liquid crystal film 30 is added and a microcavity structure between the cholesteric liquid crystal film 30 and the anode exists, the emergent light intensity is as follows
In the above formula, delta is the phase difference value between Y1 and Y2.
When the phase difference delta between Y1 and Y2 is 2 mpi (m is an integer), the emergent light intensity is maximum
From the above formula, it can be seen that the light intensity of the outgoing light can be greatly improved by adding the cholesteric liquid crystal film and the microcavity structure formed by the cholesteric liquid crystal film and the anode.
The refractive index of the existing common materials generally has positive wavelength dispersion, expressed in cauchy's simplified formula:
when the refractive index of the material has positive wavelength dispersion, A, B is greater than 0.
Constructive formula by light interferenceIt is known that in the same material and sequence structure, the microcavity structure can be formed only for light with a specific wavelength, and the light emitted by the OLED light-emitting panel is usually between 430 nm and 680nm, so that the light with the above-mentioned wavelength band forms a better microcavity effect, the optical path difference can be adjusted by adjusting the thickness of each cholesteric liquid crystal film, the ordering among the cholesteric liquid crystal films, or by adjusting the thickness and refractive index of the optical adhesive layer between the cholesteric liquid crystal film 30 and the light-emitting panel layer 40, the optical adhesive layer between adjacent cholesteric liquid crystal films or other functional layer materials.
In one possible application structure, the cholesteric liquid crystal films with three different pitches are adhered together through an optical adhesive layer, the union of the wavelength bandwidths reflected by the cholesteric liquid crystal films with three different pitches is larger than the wavelength range of light emitted by the light-emitting panel of the display panel, and the cholesteric liquid crystal films and the light-emitting panel are adhered together through optical adhesive. The light-emitting panel layer comprises a cathode, an anode, a light-emitting layer, an electron transport layer, a hole transport layer, a packaging layer and other multi-layer functional layers.
In one specific structure, as shown in fig. 6, three kinds of cholesteric liquid crystal films with different pitches are respectively a first cholesteric liquid crystal film with a pitch of P1 for regulating blue light, a second cholesteric liquid crystal film with a pitch of P2 for regulating green light and a third cholesteric liquid crystal film with a pitch of P3 for regulating red light, wherein the wavelength range of reflection light of the first cholesteric liquid crystal film is 430-480 nm, the wavelength range of reflection light of the second cholesteric liquid crystal film is 500-580 nm, and the wavelength range of reflection light of the third cholesteric liquid crystal film is 580-680 nm. From the view angle, the arrangement sequence is a third cholesteric liquid crystal film layer, a second cholesteric liquid crystal film layer and a first cholesteric liquid crystal film layer in sequence. The first cholesteric liquid crystal film layer and the second cholesteric liquid crystal film layer are adhered together through a fourth optical adhesive layer 64, the second cholesteric liquid crystal film layer and the third cholesteric liquid crystal film layer are adhered together through a fifth optical adhesive layer 65, and the first cholesteric liquid crystal film layer and the light-emitting panel are adhered together through the first optical adhesive layer.
In the structure, the cholesteric liquid crystal film and the anode form a microcavity structure, and the optical path difference calculation formula of the constructive light interference is adopted aiming at the central wavelength of blue light emitted by the light-emitting panel It is known that, in order to form the optical microcavity structure, the calculation process of the optical path difference of the circularly polarized light portion with the blue light center wavelength Y2 includes all the functional layers between the anode and the first cholesteric liquid crystal film layer in the display panel. For the central wavelength of green light emitted by the light-emitting panel, in order to form a microcavity structure, the optical path difference calculation process of the circularly polarized light part of the central wavelength Y2 of the green light comprises all functional layers except the anode and the second cholesteric liquid crystal film layer in the display panel. Aiming at the central wavelength of red light emitted by the light-emitting panel, in order to form a microcavity structure, the optical path difference calculation process of the Y2 circularly polarized light part of the red light central wavelength comprises all functional layers except the anode and the third cholesteric liquid crystal film layer in the display panel.
The arrangement of the cholesteric liquid crystal films with different pitches can be in any order, and in the process of calculating the optical path difference of Y2 part circularly polarized light with different pitches and different wavelengths in different order structures, the optical path difference functional layers required to be calculated comprise all functional layers between the cholesteric liquid crystal films with different pitches and the reflecting layers. Under the combined action of the cholesteric liquid crystal film 30 and the microcavity effect of the cholesteric liquid crystal film 30 and the light-emitting panel Yang Jijian, most of the light emitted by the light-emitting panel 40 can reach the surface of the display panel except for a part of light which is absorbed by each functional layer, the light-emitting rate is improved by 70-90% compared with the light-emitting rate under the condition that the cholesteric liquid crystal film is not added, the light-emitting intensity is about 2 times under the condition that the cholesteric liquid crystal film is not added but a microcavity structure is not formed, and the maximum light-emitting intensity is 4 times under the condition that the cholesteric liquid crystal film is not added and the microcavity structure is not formed when the cholesteric liquid crystal film is added and the microcavity structure is formed between the cholesteric liquid crystal film and the anode.
The thickness of the cholesteric liquid crystal having a certain pitch structure in the cholesteric liquid crystal film 30 is 1 to 30 times of the single pitch, further 2 to 15 times of the single pitch, and further 4 to 10 times of the single pitch.
In some embodiments, the cholesteric liquid crystal film 30 is better for regulating the polarization state of broadband light, and the cholesteric liquid crystal film 30 needs more pitch gradient layers, which can be prepared by compounding multiple layers of cholesteric liquid crystal films with different pitch sizes, or gradient distribution of different pitch sizes in the thickness direction of a single layer of cholesteric liquid crystal film 30. Wherein the wavelength of light reflected by the cholesteric liquid crystal film with one pitch size and the wavelength of light reflected by the cholesteric liquid crystal film with other pitches size can have common reflection wavelength or not.
In the structure of the cholesteric liquid crystal film 30, when a plurality of pitch gradient layers are present, the arrangement order of the cholesteric liquid crystal films of the respective pitch sizes may be any order, and is not limited herein.
In some possible applications, the cathode and anode in the light-emitting panel 40 are transparent electrodes, and a reflective layer is disposed between the light-emitting panel 40 and the substrate 50, and a microcavity structure is disposed between the cholesteric liquid crystal film 30 and the reflective layer.
The cholesteric liquid crystal film 30 shown in fig. 2 has a structure with three pitches of 31 to 33.
The cholesteric liquid crystal film 30 shown in fig. 5 has a structure having five pitch sizes of 31 to 35.
Example 2
The present embodiment provides a display panel as shown in fig. 3.
The display panel is top-emitting, and the cathode 44 in the light-emitting panel layer 40 is a semi-transparent and semi-reflective material, i.e. has a light transmittance of between 10% and 90%, further has a light transmittance of between 20% and 70%, and further has a light transmittance of between 30% and 50%. In the invention, under the conventional technical means, the cathode is designed into a semi-transparent and semi-reflective layer, a microcavity structure is formed between the cathode and the anode, and a microcavity structure between the cholesteric liquid crystal film and the reflecting electrode exists at the same time, wherein the microcavity structure between the cholesteric liquid crystal film and the cathode, or the microcavity structure between the cholesteric liquid crystal film and the anode, or the microcavity structure between the cholesteric liquid crystal film and the cathode and the microcavity structure between the cholesteric liquid crystal film and the anode exist at the same time.
When a microcavity structure is formed between the cathode and the anode, light emitted by the light-emitting panel reaches the semi-transparent and semi-reflective cathode, the transmitting part is marked as C1, the reflecting part is marked as C2, the C2 is reflected by the anode and then transmitted through the cathode part to be marked as C3, the reflecting part is marked as C4, and the C3 and the C1 form interference constructive. C4 is reflected by the anode and then passes through the cathode part and is marked as C5, the reflecting part is marked as C6, the C5 and the C1 form reflection phase, and so on until all the light is emitted after reflection.
In the microcavity structure formed between the cathode and the anode, and the microcavity structure formed between the cholesteric liquid crystal film 30 and the transflective cathode, the total light emitted from the cathode to reach the cholesteric liquid crystal film 30 is denoted by C7, the transmitted portion is denoted by C8, the reflected portion is denoted by C9, the reflected portion is denoted by C10 through the transflective cathode, the transmitted portion is denoted by C11, and the reflected C10 forms interference phase with C8 after passing through the cholesteric liquid crystal film 30, thereby improving the intensity of the emitted light.
In the microcavity structure formed between the cathode and the anode, and the microcavity structure formed between the cholesteric liquid crystal film 30 and the anode, the total light emitted from the cathode to reach the cholesteric liquid crystal film 30 is denoted by C7, the transmitted portion is denoted by C8, the reflected portion is denoted by C9, the C9 is denoted by C10 through the transflective cathode, the transmitted portion is denoted by C11, the C11 is reflected by the anode and is denoted by C12 through the transflective cathode, and the C12 forms interference constructive with the C8 after passing through the cholesteric liquid crystal film 30, thereby improving the intensity of the emitted light.
The micro-cavity structure is formed between the cathode and the anode, the micro-cavity structure is formed between the cholesteric liquid crystal film 30 and the semi-transparent semi-reflective cathode, and the micro-cavity structure is formed between the cholesteric liquid crystal film 30 and the anode, and the interference constructive between the C10 and the C8 and the interference constructive between the C12 and the C8 exist, so that the light intensity of emergent light is improved.
In the microcavity structure formed between the cholesteric liquid crystal film 30 and the reflective layer, the thickness, refractive index and arrangement sequence of each layer of the cholesteric liquid crystal films 31 to 33 can be controlled, or microcavity effects of light with different wavelengths can be achieved by controlling the thickness and refractive index of optical adhesive layers possibly existing between the cholesteric liquid crystal films, or in some possible embodiments, optical adhesive layers or other functional layer materials can exist between adjacent cholesteric liquid crystal films, between the cholesteric liquid crystal films and the electrodes, and the optical path difference can also be adjusted by adjusting the thickness and refractive index of the optical adhesive layers or other functional layers. In the case where the light-emitting panel has a plurality of light-emitting sub-pixels at the same time, and the emitted light has different wavelengths, it is preferable to realize a microcavity structure of light of different wavelengths by adjusting the arrangement order of cholesteric liquid crystal films of different pitch sizes in the cholesteric liquid crystal film 30.
Example 3
The embodiment provides a display panel.
As shown in fig. 4, in the structure of an OLED display panel, a cholesteric liquid crystal film is disposed between two layers of cathodes, wherein the side close to the viewing angle is a half-transparent half-reflective cathode, i.e. the light transmittance is 10% -90%, and the side far from the viewing angle is a transparent cathode, i.e. the light transmittance is greater than 90%. A first microcavity structure is arranged between the cholesteric liquid crystal film and the anode, and a second microcavity structure is arranged between the cholesteric liquid crystal film and the semi-transparent semi-reflective cathode. The cholesteric liquid crystal film 30 converts the light emitted from the light-emitting panel 40 into left-handed polarized light and right-handed polarized light, and when the optical selectivity of the cholesteric liquid crystal film 30 allows the left-handed polarized light (right-handed polarized light) to pass through, this portion is denoted as Y1, the right-handed polarized light (left-handed polarized light) is reflected back to the reflective electrode of the light-emitting panel 40, and after being reflected again by the reflective electrode, the polarization direction of the light is changed, i.e., the left-handed polarized light (right-handed polarized light) is changed to right-handed polarized light (left-handed polarized light), this portion Denoted as Y2, the circularly polarized light with the changed polarization direction can smoothly pass through the cholesteric liquid crystal film 30, and the optical path difference of the circularly polarized light of Y1 and Y2 is regulated to be integral multiple of the corresponding wavelength, namelyWherein delta is Y1 For the optical path of Y1, delta Y2 For the optical path of Y2, m is a positive integer, n i Represents the refractive index of the ith functional layer, d i For the i-th functional layer thickness, j is the number of all functional layers through which Y2 passes, and λ is the reflection center wavelength. Thereby forming interference constructive of light and improving the light intensity of emergent light.
When a microcavity structure exists between the cholesteric liquid crystal film 30 and the transflective cathode, circularly polarized light emitted from the cholesteric liquid crystal film 30 is denoted as Y3, Y3 reaches the transflective cathode, a transmission part is denoted as Y4, a reflected part is denoted as Y5, the rotation direction of Y5 reflected by the transflective electrode is changed, the circularly polarized light is reflected back to the transflective cathode by the cholesteric liquid crystal film 30, at this time, the transmission part is denoted as Y6, the reflected part is denoted as Y7, the Y7 is reflected by the cholesteric liquid crystal film 30 and then passes through the transflective cathode part and is denoted as Y8, the reflected part is denoted as Y9, wherein the Y4 and the Y8 form interference phase, and the like, until all light is emitted.
Example 4
The embodiment provides a display panel.
In the structure of the OLED display panel, a cholesteric liquid crystal film is positioned between two layers of anodes, wherein the anode close to the light emitting side is a transparent electrode, and the electrode far away from the light emitting side is a reflecting electrode. When the cathode is of a transparent structure, a part of light emitted by the light-emitting panel directly exits through the cathode, and the other part of light reaches the cholesteric liquid crystal film 30 through the transparent anode, wherein the reflected circularly polarized light is marked as X1, the transmitted circularly polarized light is marked as X2, and the X2 is reflected twice through the reflective anode and then transmitted through the cholesteric liquid crystal film 30 to interfere with the X1 for constructive effect, so that the light intensity of the exiting light is improved.
The cholesteric liquid crystal film is positioned between the two layers of anodes, wherein the anode close to the light emitting side is a transparent electrode, and the electrode far away from the light emitting side is a reflecting electrode. When the cathode is of a half-transmission half-reflection structure, a part of light emitted by the light-emitting panel directly exits through the cathode, a part of the light reaches the cholesteric liquid crystal film 30 through the transparent anode, wherein the reflected part is denoted as A1, the transmitted part is denoted as A2, the light passing through the cholesteric liquid crystal film 30 after being reflected twice by the reflective anode interferes with A1 to be constructive, the light after interference constructive is denoted as A3, A3 reaches the half-reflection cathode, the transmitted part is denoted as A4, the reflected part is denoted as A5, the light passing through the cholesteric liquid crystal film after being reflected by the reflective part is denoted as A5, the light passing through the cholesteric liquid crystal film in A6 is denoted as A7, the reflected part is denoted as A8, and the light passing through the cholesteric liquid crystal film 30 is denoted as A9 again, wherein the interference constructive between A9 and A4.
In the bottom emission display panel structure, the reflective electrode is a cathode, and the cholesteric liquid crystal film may be disposed on the light-emitting side of the anode, or disposed between two layers of cathodes or two layers of anodes, where one layer of the two layers of cathodes or two layers of anodes may be an electrode of a transparent or semi-transparent semi-reflective structure. Microcavity structures like the top-emission structures exist in all of the above structures.
Example 5
The embodiment provides a display panel.
As shown in fig. 7, in an OLED display panel structure, the anode is made of a transparent material, i.e., the transmittance is greater than 90%, and a microcavity is formed between the cholesteric liquid crystal film 30 and the cathode. The cholesteric liquid crystal film 30 converts the light emitted from the light-emitting panel 40 into left-handed polarized light and right-handed polarized light, when the optical selectivity of the cholesteric liquid crystal film 30 allows the left-handed polarized light (right-handed polarized light) to pass through, this part is denoted as B1, the right-handed polarized light (left-handed polarized light) is reflected back to the reflective electrode of the light-emitting panel 40, and after being reflected again by the reflective electrode, the polarization direction of the light is changed, i.e., the left-handed polarized light (right-handed polarized light) is changed into right-handed polarized light (left-handed polarized light), this part is denoted as B2, and the circularly polarized light with the polarization direction changed can smoothly pass through the cholesteric liquid crystal film 30, the optical path difference between the B1 and the B2 circularly polarized light is an integer multiple of the corresponding wavelength, i.e Thereby forming interference constructive of light and improving the light intensity of emergent light.
In one possible embodiment, as shown in fig. 8, the anode of the light-emitting panel 40 in the OLED display panel structure is made of a semi-transparent and semi-reflective material, that is, the light transmittance is between 10% and 90%, further, the light transmittance is between 20% and 70%, and still further, the light transmittance is between 30% and 50%. Under the conventional technical means, the anode is designed into a semi-transparent and semi-reflective layer, a microcavity structure is formed between the cathode and the anode, and a microcavity structure between the cholesteric liquid crystal film and the reflecting electrode exists at the same time, wherein the microcavity structure between the cholesteric liquid crystal film and the cathode, or the microcavity structure between the cholesteric liquid crystal film and the anode, or the microcavity structure between the cholesteric liquid crystal film and the cathode and the microcavity structure between the cholesteric liquid crystal film and the anode exist at the same time.
When a microcavity structure is formed between the cathode and the anode, light emitted by the light-emitting panel reaches the semi-transparent and semi-reflective anode, the transmitting part is denoted as D1, the reflecting part is denoted as D2, the D2 is reflected by the cathode and then transmitted through the anode, the reflecting part is denoted as D3, and the reflecting part is denoted as D4, wherein the D3 and the D1 form interference constructive. D4 is reflected by the cathode and then passes through the anode part and is marked as D5, the reflecting part is marked as D6, the D5 and the D1 form reflection phase, and so on until all the light is emitted after reflection.
In the microcavity structure formed between the cathode and the anode, and the microcavity structure formed between the cholesteric liquid crystal film 30 and the transflective anode, the total light emitted from the anode to reach the cholesteric liquid crystal film 30 is denoted as D7, the transmitted portion is denoted as D8, the reflected portion is denoted as D9, the D9 is denoted as D10 through the transflective anode, the transmitted portion is denoted as D11, and the reflected D10 forms interference phase with D8 after passing through the cholesteric liquid crystal film 30, thereby improving the intensity of the emitted light.
In the microcavity structure formed between the cathode and the anode, and the microcavity structure formed between the cholesteric liquid crystal film 30 and the cathode, the total light emitted from the anode to reach the cholesteric liquid crystal film 30 is denoted as D7, the transmitted portion is denoted as D8, the reflected portion is denoted as D9, the D9 is denoted as D10 through the transflective anode, the transmitted portion is denoted as D11, the D11 is reflected by the cathode and is denoted as D12 through the transflective anode, and the D12 forms interference constructive with the D8 after passing through the cholesteric liquid crystal film 30, thereby improving the intensity of the emitted light.
The micro-cavity structure is formed between the cathode and the anode, the micro-cavity structure is formed between the cholesteric liquid crystal film 30 and the semi-transparent semi-reflective anode, and the micro-cavity structure is formed between the cholesteric liquid crystal film 30 and the cathode, and meanwhile, the interference constructive between the D10 and the D8 and the interference constructive between the D12 and the D8 exist, so that the light intensity of emergent light is improved.
In the microcavity structure formed between the cholesteric liquid crystal film 30 and the reflective electrode, the thickness, refractive index and arrangement order of the layers of the cholesteric liquid crystal films 31 to 33 can be controlled. Or in some possible embodiments, an optical adhesive layer or other functional layer material may be present between adjacent cholesteric liquid crystal films, between the cholesteric liquid crystal films and the electrodes, and the optical path difference may be adjusted by adjusting the thickness and refractive index of the optical adhesive layer or other functional layer.
Example 6
The embodiment provides a display panel.
As shown in fig. 9, in an OLED display panel, a cholesteric liquid crystal film is disposed between two layers of anodes, wherein the side close to the viewing angle is a semi-transparent and semi-reflective anode, i.e. the light transmittance is 10% -90%, and the side far from the viewing angle is a transparent anode, i.e. the light transmittance is greater than 90%. The cathode is a reflecting electrode, and the reflectivity is more than 90%. A first microcavity structure is arranged between the cholesteric liquid crystal film and the cathode, or a second microcavity structure is arranged between the cholesteric liquid crystal film and the semi-transparent semi-reflective anode, or the first microcavity structure and the second microcavity structure are simultaneously arranged. The cholesteric liquid crystal film 30 converts the light emitted from the light-emitting panel 40 into left-handed polarized light and right-handed polarized light, when the optical selectivity of the cholesteric liquid crystal film 30 allows the left-handed polarized light (right-handed polarized light) to pass through, this portion is denoted as E1, the right-handed polarized light (left-handed polarized light) is reflected back to the reflective electrode of the light-emitting panel 40, and after being reflected again by the reflective electrode, the polarization direction of the light is changed, i.e., the left-handed polarized light (right-handed polarized light) is changed into right-handed polarized light (left-handed polarized light), this portion is denoted as E2, and the circularly polarized light with the polarization direction changed smoothly passes through the cholesteric liquid crystal film 30, the optical path difference between the E1 and E2 circularly polarized light corresponds to an integer multiple of the wavelength, i.e Wherein delta is Y1 For the optical path of Y1, delta Y2 For the optical path of Y2, m is a positive integer, n i Represents the refractive index of the ith functional layer, d i For the i-th functional layer thickness, j is the number of all functional layers through which E2 passes, and λ is the reflection center wavelength. Thereby forming interference constructive of light and improving the light intensity of emergent light.
An OLED display panel, wherein a cholesteric liquid crystal film 30 is disposed between two layers of anodes, wherein the anode adjacent to the light-emitting side is a semi-transparent semi-reflective electrode, and the anode far from the light-emitting side is a transparent electrode. When a microcavity structure exists between the cholesteric liquid crystal film 30 and the transflective anode, circularly polarized light emitted from the cholesteric liquid crystal film 30 is denoted as E3, E3 reaches the transflective anode, a transmission part is denoted as E4, a reflected part is denoted as E5, the rotation direction of E5 reflected by the transflective electrode is changed, the circularly polarized light is reflected back to the transflective anode by the cholesteric liquid crystal film 30, at this time, the transmission part is denoted as E6, the reflected part is denoted as E7, the E7 is reflected by the cholesteric liquid crystal film 30 and then is denoted as E8 by the transflective anode, the reflected part is denoted as E9, the E4 and the E8 form interference phase, and the like, until all light is emitted.
Example 7
The embodiment provides a display panel.
As shown in fig. 10, in an OLED display panel, a cholesteric liquid crystal film is disposed between two layers of cathodes, wherein the cathode near the light emitting side is a transparent electrode, and the cathode far from the light emitting side is a reflective electrode. When the anode is of a transparent structure, a part of light emitted by the light-emitting panel directly exits through the cathode, and the other part of light reaches the cholesteric liquid crystal film 30 through the transparent cathode, wherein the reflected circularly polarized light is marked as F1, the transmitted circularly polarized light is marked as F2, and after being reflected twice through the reflective cathode, the F2 is transmitted through the cholesteric liquid crystal film 30 to interfere with F1 for constructive interference, so that the light intensity of the exiting light is improved.
In one embodiment, the cholesteric liquid crystal film is positioned between two layers of cathodes, wherein the cathode adjacent to the light-emitting side is a transparent electrode and the electrode remote from the light-emitting side is a reflective electrode. When the anode is of a half-transmission half-reflection structure, a part of light emitted by the light-emitting panel directly exits through the anode, a part of the light reaches the cholesteric liquid crystal film 30 through the transparent cathode, wherein the reflected part is denoted as G1, the transmitted part is denoted as G2, the G2 is reflected twice through the reflective cathode and then interferes with the G1 to be constructive, the light with constructive interference is denoted as G3, the G3 reaches the half-transmission anode, the transmitted part is denoted as G4, the reflected part is denoted as G5, the G5 is reflected through the cholesteric liquid crystal film and then denoted as G6, the part of the G6 directly penetrates through the half-transmission half-reflection anode and is denoted as G7, the reflected part is denoted as G8, and the G8 is reflected again through the cholesteric liquid crystal film 30 and then penetrates through the half-transmission half-reflection anode and is denoted as G9, wherein the G9 is constructive with the G4.
In some other possible application structures, cholesteric liquid crystal films of different pitch sizes are prepared for different light lengths, and can be placed at different positions of the display device, respectively, such as between two layers of cathodes for blue light, and between the cathodes and the phase retardation film layer for red and green light. Or other possible arrangement and distribution order, without specific limitation.
The cholesteric liquid crystal film 30 in the above embodiment may be a cholesteric derivative liquid crystal material or a chiral nematic liquid crystal material or a liquid crystal material prepared by adding a chiral compound to a discotic liquid crystal, which is not limited herein.
The cholesteric liquid crystal film 30 has a birefringence of 0.01 to 0.5, further, a birefringence of 0.05 to 0.35, and further, in the first step, a birefringence of 0.1 to 0.3.
In one possible embodiment, the phase retarder layer 20 is formed by pasting one or more phase retarders.
Illustratively, the phase retardation film layer 20 is formed by compression-bonding a single-layer or multi-layer polycarbonate film with a silicon oxide and zirconium oxide film or is prepared from a single-layer or multi-layer nematic liquid crystal polymer film material. The phase retardation film is at least one of a polymer stretching type reverse dispersion quarter-phase retardation film, a polymer stretching type A plate quarter-phase retardation film, a liquid crystal type reverse dispersion composite quarter-phase retardation film, a liquid crystal type A plate quarter-phase retardation film, a liquid crystal type O plate quarter-phase retardation film, and a liquid crystal type biaxial quarter-phase retardation film.
In one possible embodiment, the linear polarizing plate layer 10 is formed by sticking two layers of cellulose triacetate with a layer of polyvinyl alcohol interposed therebetween.
For example, the linear polarizing plate layer 10 may use an iodine-based polarizing plate. In the above-described structure of the linear polarizing plate layer 10, a cellulose Triacetate (TAC) side is coated with a pressure-sensitive adhesive (PSA film), a Release film (Release film), and a Protective film (Protective film).
In one possible embodiment, the linear polarizing plate layer 10 is a linear polarizing plate prepared from a liquid crystal material doped with a dichroic dye.
In one possible embodiment, the cholesteric liquid crystal film 30, the phase retardation film layer 20, and the linear polarizing plate layer 10 may be all liquid crystal polymer materials, and are combined together through a unified polymerization reaction, or the cholesteric liquid crystal film 30, the phase retardation film layer 20, and the linear polarizing plate layer 10 are combined together in pairs through a unified polymerization reaction.
Device example 1
The embodiment of the device provides a display based on the OLED display panel.
Illustratively, the display includes an bezel, a control circuit board, and the like in addition to the above-described OLED display panel.
An OLED display panel, the schematic structural diagram of which is shown in fig. 2, includes a substrate layer 50, a light-emitting panel layer 40, an optical adhesive layer 61, a cholesteric liquid crystal film 30, an optical adhesive layer 62, a phase retardation film layer 20, an optical adhesive layer 62 and a linear polarizing panel layer 10, which are sequentially arranged, wherein a side of the linear polarizing panel layer 10 far away from the light-emitting panel layer 10 is a light-emitting side. The cathode is a transparent electrode, the light transmittance is 98%, the anode is a reflecting electrode, the reflectivity is 97%, the refractive index of the packaging layer of the light-emitting panel layer 40, which is close to the cholesteric liquid crystal film 30 side, is 1.7, the thickness is 100nm, the refractive index of the cathode is 2.2, the thickness is 80nm, the refractive index of the light-emitting layer is 1.66, the thickness is 60nm, the refractive index of the optical adhesive layer 61 is 1.65, the thickness is 1135nm, the average refractive index of the cholesteric liquid crystal film 30 is 1.6, the double refractive index is 0.2, 31 in the cholesteric liquid crystal film is a first cholesteric liquid crystal film layer, and the cholesteric pitch P in the first cholesteric liquid crystal film layer 31 =288 nm, reflection center wavelength of460nm, the thickness of the first cholesteric liquid crystal film is 2500nm,32 is a second cholesteric liquid crystal film layer, and the cholesteric pitch P in the second cholesteric liquid crystal film layer 32 =331 nm, the second cholesteric liquid crystal film layer has a thickness of 3200nm, the reflection center wavelength is 530nm,33 is a third cholesteric liquid crystal film layer, and the cholesteric pitch P in the third cholesteric liquid crystal film layer 33 =388 nm, the reflection center wavelength was 620nm, and the third cholesteric liquid crystal film thickness was 3300nm. The refractive index of the optical adhesive layer 62 is 1.58, the refractive index of the phase retardation film layer 20 is 1.6, the refractive index of the optical adhesive layer 63 is 1.6, and the refractive index of the linear polarizing plate layer 10 is 1.62. By the arrangement, the microcavity structure can be formed for the light with the center wavelength distribution of 460nm,530nm and 620nm emitted by the display panel.
Under the condition that the cholesteric liquid crystal film 30 is added and a microcavity structure between the cholesteric liquid crystal film 30 and the anode exists, the emergent light intensity is as follows
In the above formula, delta is the phase difference value between Y1 and Y2.
Maximum intensity of emitted light in the above
Comparative example 1
The present comparative example provides an OLED display panel.
An OLED display panel comprises a substrate layer 50, a light-emitting panel layer 40, an optical adhesive layer 61, a phase delay film layer 20, an optical adhesive layer 62 and a linear polarizing plate layer 10 which are sequentially arranged, wherein one side, far away from the light-emitting panel layer 10, of the linear polarizing plate layer 10 is a light-emitting side. The cathode is a transparent electrode, the light transmittance is 98%, the anode is a reflective electrode, the reflectivity is 97%, the refractive index of the packaging layer of the light-emitting panel layer 40 near the phase retardation film layer 20 side is 1.7, the thickness is 100nm, the refractive index of the cathode is 2.2, the thickness is 80nm, the refractive index of the light-emitting layer is 1.66, the thickness is 60nm, the refractive index of the optical adhesive layer 61 is 1.65, the thickness is 1135nm, the refractive index of the phase retardation film layer 20 is 1.6, the refractive index of the optical adhesive layer 62 is 1.6, and the refractive index of the linear polarizing plate layer 10 is 1.62. The OLED display device has the emergent light intensity:
In the above, I Y1 +I Y2 For the light intensity of the emergent light of the luminous panel, I Y1 ≈I Y2 。
Comparative example 2
The present comparative example provides an OLED display panel.
An OLED display panel comprises a substrate layer 50, a light-emitting panel layer 40, an optical adhesive layer 61, a phase delay film layer 20, an optical adhesive layer 62 and a linear polarizing plate layer 10 which are sequentially arranged, wherein one side, far away from the light-emitting panel layer 10, of the linear polarizing plate layer 10 is a light-emitting side. The cathode is a semi-transparent and semi-reflective electrode, the light transmittance is 40%, the reflectivity is 58%, the anode is a reflective electrode, the reflectivity is 97%, the refractive index of the packaging layer of the light-emitting panel layer 40, which is close to the phase retardation film layer 20, is 1.7, the thickness is 100nm, the refractive index of the cathode is 2.2, the thickness is 80nm, the refractive index of the light-emitting layer is 1.66, the thickness is 140nm, the refractive index of the optical adhesive layer 61 is 1.65, the thickness is 1135nm, the refractive index of the phase retardation film layer 20 is 1.6, the refractive index of the optical adhesive layer 62 is 1.6, and the refractive index of the linear polarizing plate layer 10 is 1.62. In the display panel structure, a better microcavity effect can be formed only for a single central wavelength of 460nm, and the influence on light of other wavelengths is small. Thus causing color shift problems in the outgoing light of the display panel. For 460nm wavelength light, the emergent light intensity is:
as can be seen from the above embodiments, the light intensity of the outgoing light can be greatly improved by adding the cholesteric liquid crystal film and the microcavity structure formed by the cholesteric liquid crystal film and the anode. From the formula It can be seen that the light of different wavelengths is shapedThe microcavity effect needs to correspond to different optical path differences, and can be realized by adjusting the thickness of each cholesteric liquid crystal film and the ordering among the cholesteric liquid crystal films.
Under the combined action of the cholesteric liquid crystal film 30 and microcavity effects of the cholesteric liquid crystal film 30 and the light-emitting panel Yang Jijian, most of light emitted by the light-emitting panel 40 can reach the surface of the display except for a part of light which is absorbed by each functional layer, the light-emitting rate is improved by 70-90% compared with the light-emitting rate under the condition that the cholesteric liquid crystal film is not added, the light-emitting rate is improved by about 2 times under the condition that the cholesteric liquid crystal film is not added but a microcavity structure is not formed, the maximum light-emitting rate is 4 times under the condition that the cholesteric liquid crystal film is not added and the microcavity structure is not formed when the cholesteric liquid crystal film is added and the microcavity structure is formed between the cholesteric liquid crystal film and the anode.
The present invention may be better implemented as described above, and the above examples are merely illustrative of preferred embodiments of the present invention and not intended to limit the scope of the present invention, and various changes and modifications made by those skilled in the art to the technical solution of the present invention should fall within the scope of protection defined by the present invention without departing from the spirit of the design of the present invention.
Claims (10)
1. An OLED display panel comprising: the light-emitting panel, the cholesteric liquid crystal film, the phase delay film and the linear polarizing plate, wherein the cholesteric liquid crystal film is arranged on the light-emitting side of the light-emitting panel,
the phase delay film is used for converting circularly polarized light and linearly polarized light;
the linear polarizing plate absorbs polarized light with the vibration direction perpendicular to the transmission axis, transmits polarized light parallel to the transmission axis, and converts unpolarized light into linear polarized light after passing through the linear polarizing plate;
the light emitting panel has at least one reflective layer;
the cholesteric liquid crystal film converts the emitted unpolarized light emitted by the light-emitting panel into first polarized light and second polarized light, wherein the first polarized light is selected from one of left-handed circularly polarized light and right-handed circularly polarized light, and the second polarized light has a polarization direction opposite to that of the first polarized light;
the cholesteric liquid crystal film selectively allows the first polarized light to pass through, and the second polarized light passes through the cholesteric liquid crystal film after being reflected by the reflecting layer;
the optical path of the first polarized light is Y1, the optical path of the second polarized light is Y2, the optical path difference between the Y1 and the Y2 is different by an integer multiple of the optical wavelength, and the cholesteric liquid crystal film and the reflecting layer form a microcavity structure.
2. The OLED display panel according to claim 1, wherein the optical path difference between Y1 and Y2 is satisfied by adjusting at least one of a or b by an integer multiple of the wavelength of light, i.e., the formula:
wherein delta is Y1 For the optical path of Y1, delta Y2 For the optical path of Y2, m is a positive integer, n i Represents the refractive index of the ith functional layer, d i For the thickness of the ith functional layer, j is the number of all functional layers through which Y2 passes, and lambda is the reflection center wavelength;
a. at least one of pitch gradient, thickness, refractive index, arrangement sequence of different pitches and inclination angle in the cholesteric liquid crystal film;
b. the cholesteric liquid crystal film is in position in the OLED display panel.
3. The OLED display panel according to claim 2, wherein in condition a, the cholesteric liquid crystal film is made of a polymeric liquid crystal material having at least one pitch gradient therein, and the pitch has a thickness of between 0.1 and 10 μm.
4. The OLED display panel claimed in claim 3, wherein a pitch gradient is present in the polymeric liquid crystal material;
the reflection center wavelength and reflection bandwidth of the cholesteric liquid crystal film with single pitch satisfy the following formula:
λ＝n*P*cosθ
Δλ＝Δn*P*cosθ
Wherein lambda is the reflection center wavelength, n is the average refractive index of the cholesteric liquid crystal film, P is the pitch of the cholesteric liquid crystal, delta lambda is the reflection wavelength bandwidth, delta n is the refractive index of the cholesteric liquid crystal film, and theta is the included angle between the light incident angle and the helical center axis of the cholesteric liquid crystal.
5. The OLED display panel of claim 3, wherein a plurality of pitch gradients are present in the polymeric liquid crystal material;
the reflection light wave bandwidths of the cholesteric liquid crystal film with various screw pitch structures are the union of the reflection bandwidths of the screw pitches, and the following formula is satisfied:
Δλ＝Δn 1 *P 1 *cosθ 1 ∪Δn 2 *P 2 *cosθ 2 ∪Δn 3 *P 3 *cosθ 3 ···∪Δn n *P n *cosθ n
wherein P is the pitch of cholesteric liquid crystal, deltalambda is the reflection wavelength bandwidth, deltan is the birefringence of the brightness enhancement film, and theta is the included angle between the incident angle of light and the central axis of cholesteric liquid crystal spiral.
6. The OLED display panel of claim 5, wherein the polymeric liquid crystal material has a thickness of 3 pitch or more;
preferably, the thickness of the polymer liquid crystal material is more than or equal to 6 screw pitch thickness.
7. The OLED display panel according to claim 2, wherein in the condition b, the OLED display panel is of a top-emission type structure, and the cholesteric liquid crystal film is located at any one of c to e:
c. The cholesteric liquid crystal film is arranged between the phase delay film and the cathode, and the cathode is selected from a transparent electrode or a semi-transparent semi-reflective electrode;
d. the anode comprises a first anode and a second anode, the first anode is a reflecting electrode, the second anode is selected from a transparent electrode or a semitransparent electrode, and the cholesteric liquid crystal film is arranged between the first anode and the second anode;
e. the cathode comprises a first cathode and a second cathode, the light-emitting layer, the first cathode, the cholesteric liquid crystal film and the second cathode are sequentially arranged, and the first cathode and the second cathode are selected from the group consisting of: the first cathode is a semi-transparent and semi-reflective electrode, the second cathode is a transparent electrode, the first cathode and the second cathode are both semi-transparent and semi-reflective electrodes, and the first cathode and the second cathode are both transparent electrodes.
8. The OLED display panel according to claim 2, wherein in the condition b, the OLED display panel is of a bottom emission type structure, and the cholesteric liquid crystal film is located at any one of f to h:
f. the cholesteric liquid crystal film is arranged between the phase delay film and the anode, and the anode is selected from a transparent electrode or a semi-transparent semi-reflective electrode;
g. The cathode comprises a first cathode and a second cathode, the first cathode is a reflecting electrode, the second cathode is selected from a transparent electrode or a semitransparent electrode, and the cholesteric liquid crystal film is arranged between the first cathode and the second cathode;
h. the anode comprises a first anode and a second anode, the light-emitting layer, the first anode, the cholesteric liquid crystal film and the second anode are sequentially arranged, and the first anode and the second anode are selected from the group consisting of: the first anode is a semi-transparent semi-reflective electrode, the second anode is a transparent electrode, the first anode and the second anode are both semi-transparent semi-reflective electrodes, and the first anode and the second anode are both one of transparent electrodes.
9. The OLED display panel according to claim 1, wherein the light-emitting panel, the cholesteric liquid crystal film, the phase retardation film, and the linear polarizing plate are connected by an optical adhesive, and a refractive index of the optical adhesive is intermediate between refractive indexes of upper and lower layers connected by the optical adhesive.
10. A display comprising an OLED display panel according to any one of claims 1-9.
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