CN115249773A

CN115249773A - OLED panel capable of adjusting color based on alternating current driving voltage frequency

Info

Publication number: CN115249773A
Application number: CN202110446088.XA
Authority: CN
Inventors: 周炜; 赵永彬; 谢鑫
Original assignee: Keze New Materials Co ltd
Current assignee: Keze New Materials Co ltd
Priority date: 2021-04-25
Filing date: 2021-04-25
Publication date: 2022-10-28

Abstract

The invention discloses an OLED panel for adjusting color based on alternating current driving voltage frequency, which comprises an OLED light-emitting device and an external alternating current driving power supply, wherein the OLED light-emitting device sequentially comprises an anode, a functional layer, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode; the light-emitting layer consists of a first light-emitting layer, a second light-emitting layer and an organic thin film layer positioned between the two light-emitting layers, and the organic thin film layer is a transparent thin film layer which is formed by a hole transmission type main body material and has the thickness of 2-6 nm. Experiments prove that the OLED panel not only can realize direct light emission driven by an alternating current power supply, but also can realize the regulation and control of the color of an OLED light-emitting device under the condition of stable and unchanged brightness by adjusting the frequency of alternating current driving voltage.

Description

OLED panel capable of adjusting color based on alternating current driving voltage frequency

Technical Field

The invention relates to an OLED panel for adjusting color based on alternating current driving voltage frequency, and belongs to the technical field of light-emitting devices.

Background

Organic electroluminescent devices (OLEDs), which are formed by stacking a cathode, an anode, and organic light emitting materials between the cathode and the anode, have advantages of low cost, low power consumption, high brightness, wide viewing angle, thin thickness, etc., and have been widely used in the display and lighting fields through decades of development. Among them, the light source with variable color has many applications in the field of car lights, for example, the tail light, turn signal light, brake light and back light of the car are all different red, orange yellow or white, and a single light source capable of emitting these colors at the same time would be popular.

Patent CN209213730 discloses a color-changeable vehicular lamp, which is characterized in that a layer of electrochromic material is added into a transparent conductive layer, and the electrochromic material is controlled to generate color change by powering on and powering off the upper and lower transparent conductive layers. However, this method can produce only simple colors such as transparency, haze, black, etc., and this material causes color change and also reduces the luminous efficiency.

A color tunable white OLED light emitting panel incorporating a fuse to improve yield is disclosed in patent US8,836,223. However, all of these panels use red, green, blue (RGB) pixels or stripes to form the color toning function. This configuration requires the use of photolithography, which is a costly and complex process step. In addition, the red, green and blue edge-to-edge mode on one substrate means that the evaporation of the organic layers of three colors needs to be completed in one operation. In this case, a fine reticle is typically used to distinguish each color with high precision alignment. It is clear that such high device performance comes at the expense of increased process cost and complexity, and does not make widespread use possible.

In patent CN109253404 it is proposed to bond at least two OLED light-emitting panels of different colors to achieve color tunability. Although this approach can avoid the complicated process of integrating different colors within one device structure, the final product becomes massive and the luminous efficiency is lost due to the use of transparent devices.

Patent CN103000822 discloses a white organic OLED light emitting device using four kinds of blue, green, yellow and red dyes doped in two different main materials to realize adjustable color temperature, and different exciton recombination regions are formed according to different applied voltages, so as to realize the conversion from cold white light to warm white light.

In addition, the structure and the light-emitting principle of the conventional OLED light-emitting device can only be driven by a dc power supply, and a standard ac power supply needs to be converted into a dc power supply required by the OLED light-emitting device through an additionally arranged ac-dc conversion device, so that high use cost is caused. Although the patent CN107768527 discloses a small molecule OLED surface light emitting device driven by ac power, which can realize the lighting by driving the OLED with standard ac power without rectifier and inverter, the patent does not disclose and suggest how to realize the color control function of the OLED light emitting device under the condition of stable and constant brightness, and cannot meet the requirement of realizing color control under the condition of constant brightness.

Disclosure of Invention

In view of the above problems in the prior art, an object of the present invention is to provide an OLED panel capable of adjusting color based on ac driving voltage frequency, which not only can realize that an ac power supply directly drives an OLED light emitting device to emit light, but also can realize color control of the OLED light emitting device under stable and unchanged brightness.

In order to realize the purpose of the invention, the technical scheme adopted by the invention is as follows:

an OLED panel capable of adjusting color based on alternating current driving voltage frequency comprises an OLED light-emitting device and an external alternating current driving power supply, wherein the OLED light-emitting device sequentially comprises an anode, a functional layer, a hole injection layer, a hole transmission layer, a light-emitting layer, an electron transmission layer, an electron injection layer and a cathode; the method is characterized in that: the light-emitting layer consists of a first light-emitting layer, a second light-emitting layer and an organic thin film layer positioned between the two light-emitting layers, and the organic thin film layer is a transparent thin film layer which is formed by a hole-transport type main body material and has the thickness of 2 nm-6 nm.

In a preferred embodiment, the functional layer is a transparent thin film layer having a thickness of 200nm to 400nm and made of a semiconductor material having a dielectric constant of 30 or more.

More preferably, the functional layer is a transparent thin film layer made of a zinc oxide (ZnO) semiconductor material and having a thickness of 250nm to 350 nm.

In a preferred embodiment, the first light-emitting layer and the second light-emitting layer are different single-component light-emitting materials or host-guest light-emitting materials.

In a preferred embodiment, the intrinsic emission peak wavelength of the first light-emitting layer differs from the intrinsic emission peak wavelength of the second light-emitting layer by at least 30nm.

In a preferred embodiment, the total thickness of the light-emitting layer is 26nm to 30nm, where: the thickness of the first light-emitting layer is 12 nm-16 nm, and the thickness of the second light-emitting layer is 8 nm-12 nm.

In a preferable embodiment, the frequency of the ac driving voltage is adjusted to be in a range of 50 hz to 20 khz.

Further preferably, the frequency of the ac driving voltage is adjusted within a range of 1 khz to 5 khz.

In a preferred scheme, the organic thin film layer is made of arylamine hole transport materials.

In a further preferable scheme, the organic thin film layer is made of a tri (4-carbazolyl-9-yl phenyl) amine (TCTA) material.

Compared with the prior art, the invention has the following beneficial effects:

experiments prove that the OLED panel can realize direct light emission driven by an alternating current power supply, can realize color regulation and control of an OLED light-emitting device under the condition of stable and unchanged brightness by regulating the frequency of alternating current driving voltage, can meet the requirement of realizing color regulation of the OLED panel under the condition of unchanged brightness, has low manufacturing cost and easy industrial implementation, and particularly has the thickness of no more than 3 micrometers and is very light and thin; therefore, the invention has wide application space, and has obvious progress and wide application value compared with the prior art.

Drawings

Fig. 1 is a schematic structural diagram of an OLED panel for adjusting color based on ac driving voltage frequency according to an embodiment of the present invention;

the numbers in the figures are as follows: 01. an anode; 02. a functional layer; 03. a hole injection layer; 04. a hole transport layer; 05. a light emitting layer; 051. a first light-emitting layer; 052. an organic thin film layer; 053. a second light emitting layer; 06. an electron transport layer; 07. an electron injection layer; 08. a cathode; A. a cavity; B. electrons; C. exciton recombination centers.

Detailed Description

The technical solution of the present invention is fully described in detail with reference to the following embodiments and accompanying drawings.

Examples

As shown in fig. 1, the OLED panel for adjusting color based on ac driving voltage frequency provided in this embodiment includes an OLED light emitting device and an external ac driving power supply (not shown in the figure), where the OLED light emitting device includes an anode 01, a functional layer 02, a hole injection layer 03, a hole transport layer 04, a light emitting layer 05, an electron transport layer 06, an electron injection layer 07, and a cathode 08 in this order; the light-emitting layer 05 is composed of a first light-emitting layer 051, a second light-emitting layer 053 and an organic thin film layer 052 positioned between the two light-emitting layers, the organic thin film layer 052 is a transparent thin film layer with the thickness of 2 nm-6 nm and formed by a hole transport type main body material, and the hole transport type main body material is preferably an arylamine type hole transport material, for example: tris (4-carbazolyl-9-ylphenyl) amine (TCTA) materials. The first light-emitting layer 051 and the second light-emitting layer 053 can be made of different single-component light-emitting materials, and can also be made of host and guest light-emitting materials. The intrinsic emission peak wavelength of the first light emitting layer 051 differs from the intrinsic emission peak wavelength of the second light emitting layer 053 by at least 30nm, for example: the first light-emitting layer 051 is made of a light-emitting material with a yellow intrinsic emission peak wavelength, and the second light-emitting layer 053 is made of a light-emitting material with a red intrinsic emission peak wavelength. The total thickness of the light-emitting layer 05 is 26nm to 30nm, wherein: the thickness of the first light-emitting layer is 12 nm-16 nm, and the thickness of the second light-emitting layer is 8 nm-12 nm.

The frequency of the alternating current driving voltage is adjusted within a range of 50 hz to 20 khz, preferably 2khz to 4 khz. In a half cycle of alternating current, holes A and electrons B generated by injected current or electric field induced current enter the light emitting layer 05 from the anode 01 and the cathode 08 of the OLED light emitting device respectively to be recombined to generate excitons, and the excitons undergo transition to return to a ground state to emit light; and in the other half period of the alternating current, the redundant charge return electrode is not combined, so that the OLED can emit light under the driving of the alternating current power supply.

The functional layer 02 provided by the invention is used for generating an alternating electric field between two electrodes under an alternating current power supply, so that the luminescent material on the luminescent layer 05 is excited to emit light under the alternating electric field, and the OLED luminescent device is driven by the alternating current power supply to emit light.

The functional layer 02 of the present invention may be a transparent thin film layer having a thickness of 200nm to 400nm, which is made of a semiconductor material having a dielectric constant of 30 or more. As a preferred scheme, the functional layer 02 is a transparent thin film layer with a thickness of 250nm to 350nm and made of a zinc oxide (ZnO) semiconductor material, and through the design of the specific material and the thickness, the light-emitting material can be excited to emit light under an alternating electric field without additionally arranging an alternating current-direct current conversion device, so that the OLED light-emitting device can achieve the highest brightness and the maximum light-emitting efficiency under the designed high frequency, the OLED light-emitting device can efficiently emit light under the driving of an alternating current power supply, the use cost of the OLED lighting panel is greatly reduced, the alternating current driving voltage frequency of the OLED light-emitting device can be regulated, the regulation of the alternating current driving voltage frequency within a certain range is realized (namely, the voltage and the brightness cannot be influenced in the regulation process within the range), the exciton recombination center position is moved, and the color regulation and control of the OLED light-emitting device are realized, and the specific operation is as follows:

firstly, detecting the range of the driving frequency of the alternating current power supply when the manufactured OLED light-emitting device can keep voltage and brightness stable (namely, the change rate is less than 5%), for example: 32 kHz-38 kHz;

then adjusting the driving frequency of the alternating current power supply to a certain value (for example: 33 kHz) in the frequency range, so that the exciton recombination center C is positioned at the first light-emitting layer 051, and the light-emitting color of the OLED light-emitting device is determined by the intrinsic emission spectrum color of the first light-emitting layer;

when the driving frequency of the alternating current power supply is further adjusted to another value (for example, 35 kHz) in the above frequency range, so that the exciton recombination center C is located in the organic thin film layer 052, the light-emitting color of the OLED light-emitting device is determined by the spectrum color formed by overlapping the intrinsic emission spectra of the two light-emitting layers;

when the driving frequency of the AC power is further adjusted to another value (e.g. 37 kHz) within the above frequency range, the exciton recombination center C is located in the second light-emitting layer 053, and the light-emitting color of the OLED light-emitting device is determined by the intrinsic emission spectrum color of the second light-emitting layer;

therefore, in the color adjusting process, the stable brightness of the OLED light-emitting device can be ensured, the problem that the brightness can be changed when the color adjusting process is realized in the prior art is solved, and the color adjusting device is simple in structure and low in use cost.

The following is a specific example of implementing color control by using a single ac-driven OLED light emitting device under varying drive voltage frequency:

the OLED panel comprises an OLED light-emitting device and an external alternating current driving power supply (not shown in the figure), wherein the OLED light-emitting device sequentially comprises an anode 01, a functional layer 02, a hole injection layer 03, a hole transport layer 04, a light-emitting layer 05, an electron transport layer 06, an electron injection layer 07 and a cathode 08; the light emitting layer 05 is composed of a first light emitting layer 051, a second light emitting layer 053 and an organic thin film layer 052 arranged between the two light emitting layers.

The functional layer 02 is a transparent film which is formed by zinc oxide (ZnO) semiconductor materials and has the thickness of 300nm, the first light-emitting layer 051 is made of a light-emitting material with yellow intrinsic emission peak wavelength, the second light-emitting layer 053 is made of a light-emitting material with red intrinsic emission peak wavelength, the first light-emitting layer is 14nm, the second light-emitting layer is 10nm, and the organic film 052 is a transparent film which is formed by a hole transmission type main body material tris (4-carbazolyl-9-yl phenyl) amine (TCTA) and has the thickness of 2nm to 6 nm.

The anode 01, the hole injection layer 03, the hole transport layer 04, the electron transport layer 06, the electron injection layer 07 and the cathode 08 all adopt the prior art, such as: the anode 01 can be a transparent conductive film made of materials such as ITO, IZO, au, pt and Si, the hole injection layer 03 can be a transparent film made of materials such as CuPc (copper phthalocyanine), tiOPc, m-MTDATA and 2-TNATA, the hole transport layer 04 can be a transparent film made of materials such as TPD, NPB, PVK, spiro-TPD and Spiro-NPB, the electron transport layer 06 can be a transparent film made of materials such as Alq3, almq3, DVPBi, TAZ, OXD, PBD, BND and PV, the electron injection layer 07 can be a transparent film made of materials such as LiF, mgP, mgF2 and Al2O3, and the cathode 08 can be a metal film made of materials such as Ag, al, li, mg, ca and In; and the thicknesses of the hole injection layer 03, the hole transport layer 04, the electron transport layer 06 and the electron injection layer 07 are all between 0.1nm and 300nm.

Experiments show that the OLED light-emitting device keeps the stable brightness of the driving voltage frequency between 32kHz and 38kHz, and when the driving voltage frequency is adjusted to be 33kHz, the exciton recombination center C is positioned in the first light-emitting layer 051 and emits yellow light; when the driving voltage frequency is adjusted to 35kHz, the exciton recombination center C is positioned in the organic thin film layer 052 and emits orange light; when the driving voltage frequency is adjusted to 37kHz, the exciton recombination center C is located in the second light emitting layer 053, emitting red light.

In the color adjusting process, only the driving voltage frequency is changed, the voltage and the current are not changed, and the driving voltage frequency is still in the range of stable luminance of the OLED light-emitting device, so that the technology of the invention can realize that the OLED light-emitting device is directly driven by an alternating current power supply to emit light, can realize color adjustment and control on the OLED light-emitting device under the condition of stable luminance, can meet the requirement of color adjustment of an OLED panel under the condition of unchanged luminance, has low manufacturing cost of the whole OLED light-emitting device, is easy for industrial implementation, and particularly has the thickness of not more than 3 microns and is very light and thin; therefore, the invention has wide application space, and has obvious progress and wide application value compared with the prior art.

Finally, it should be pointed out here that: the above is only a part of the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention, and the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above description are intended to be covered by the present invention.

Claims

1. An OLED panel for adjusting color based on alternating current driving voltage frequency comprises an OLED light-emitting device and an external alternating current driving power supply, wherein the OLED light-emitting device sequentially comprises an anode, a functional layer, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode; the method is characterized in that: the light-emitting layer consists of a first light-emitting layer, a second light-emitting layer and an organic thin film layer positioned between the two light-emitting layers, and the organic thin film layer is a transparent thin film layer which is formed by a hole-transport type main body material and has the thickness of 2 nm-6 nm.

2. The OLED panel of claim 1, wherein: the functional layer is a transparent thin film layer with a thickness of 200 nm-400 nm, which is made of a semiconductor material with a dielectric constant of more than 30.

3. The OLED panel of claim 2, wherein: the functional layer is a transparent film layer which is made of zinc oxide semiconductor material and has the thickness of 250 nm-350 nm.

4. The OLED panel of claim 1, wherein: the first light-emitting layer and the second light-emitting layer are made of different single-component light-emitting materials or host-guest light-emitting materials.

5. The OLED panel of claim 1 or 4, wherein: the intrinsic emission peak wavelength of the first light emitting layer differs from the intrinsic emission peak wavelength of the second light emitting layer by at least 30nm.

6. The OLED panel of claim 1, wherein: the total thickness of the luminescent layer is 26 nm-30 nm, wherein: the thickness of the first light-emitting layer is 12 nm-16 nm, and the thickness of the second light-emitting layer is 8 nm-12 nm.

7. The OLED panel of claim 1, wherein: the frequency of the alternating current driving voltage is adjusted within the range of 50 Hz to 20 kHz.

8. The OLED panel of claim 7, wherein: the adjustment range of the alternating current driving voltage frequency is 1 kilohertz to 5 kilohertz.

9. The OLED panel of claim 1, wherein: the organic film layer is made of arylamine hole transport materials.

10. The OLED panel of claim 9, wherein: the organic film layer is made of a tri (4-carbazolyl-9-yl phenyl) amine material.