CN105938284A - White fluorescence cholesteric liquid crystal device based on chiral ions, and preparation technology thereof - Google Patents

Abstract

The invention discloses a chiral ion-based white fluorescent cholesteric liquid crystal device, which is composed of two transparent substrate layers and a single-layer cholesteric liquid crystal layer sandwiched therebetween. The invention has simple process and strong implementability, the device presents white fluorescent light, has high color rendering index and can be quickly switched.

Description

A chiral ion-based white fluorescent cholesteric liquid crystal device and its preparation process

technical field

The invention relates to the field of liquid crystal devices, in particular to a chiral ion-based white fluorescent cholesteric liquid crystal device and a preparation process thereof.

Background technique

White light materials have superior performance in terms of color fidelity, so it has great potential in visible light displays and lighting. In recent years, great achievements have been made in the research of white light materials and devices. White light materials can be obtained by physical mixing or chemical synthesis of chromophores with complementary emission colors. Therefore, the generation of white light usually depends on the synthesis method and preparation process of white light materials. At present, there are mainly three methods for people to obtain white electroluminescence: (1) Doping fluorescent dyes in the light-emitting layer, through the incomplete energy transmission between the host material and the guest material, the two emit light of different colors at the same time, Thereby realizing white electroluminescence; (2) In multilayer light-emitting devices including red, blue and green light-emitting layers, the recombination region of carriers is adjusted through the energy level matching of different materials, or the electron (hole) blocking layer is used to Obtain white light; (3) The superposition of the three primary colors red, green and blue. However, the purity of materials and the operational stability of devices are the biggest problems of white light materials and their devices. The reasons of high cost, low efficiency, low device external coupling efficiency, and poor operation stability also affect the application of white light devices.

Therefore, designing and inventing a white fluorescent device with a high color rendering index and fast adjustment is an urgent technical problem to be solved at present.

Contents of the invention

The object of the present invention is to provide a white fluorescent cholesteric liquid crystal device based on chiral ions and its preparation process, so as to solve the problem of low color rendering index and inability to quickly adjust the white fluorescent device.

In order to achieve the above object, the technical scheme adopted in the present invention is:

The described chiral ion-based white fluorescent cholesteric liquid crystal device is characterized in that: it includes two transparent substrate layers and a single-layer cholesteric liquid crystal layer sandwiched between the two transparent substrate layers, wherein the light emitting The material is doped in the liquid crystal layer, and the cholesteric liquid crystal is composed of a nematic liquid crystal doped with a chiral agent and chiral ions, and the cholesteric liquid crystal is distributed in a helical gradient between two transparent substrate layers.

A white fluorescent cholesteric liquid crystal device based on chiral ions is characterized in that the luminescent material is distributed in the cholesteric liquid crystal. When the pitch is evenly distributed, the device exhibits a single fluorescence characteristic; when the pitch gradient is formed, the fluorescence spectrum of the device becomes wider and the color rendering index becomes higher.

The cholesteric liquid crystal is a negative liquid crystal, and the weight of doped luminescent material is 0.15%-0.25% of the weight of the nematic liquid crystal, and the cholesteric liquid crystal is composed of a nematic liquid crystal doped with a chiral agent and chiral ions The weight of the chiral agent is 4%-25% of the weight of the nematic liquid crystal, and the doped chiral ion is imidazole chiral ion, and its weight is 4%-10% of the weight of the nematic liquid crystal.

A preparation process for a white fluorescent cholesteric liquid crystal device based on chiral ions, characterized in that it comprises the following steps:

First, the nematic liquid crystal, fluorescent material, chiral agent and chiral ion are mixed and injected between the two transparent substrate layers in the liquid crystal device, and the nematic liquid crystal is mixed with the chiral agent and chiral ion to obtain the cholesteric liquid crystal. A DC electric field is applied between the two transparent substrate layers, and then switched to a high-frequency AC electric field after stabilization to obtain a stable white fluorescent cholesteric liquid crystal device.

The preparation technology of described a kind of chiral ion-based white fluorescent cholesteric liquid crystal device is characterized in that:

Applying a DC voltage of 100V on the cholesteric liquid crystal induces its pitch gradient distribution, the application time is 3s; and then applying a 100KHz high-frequency AC voltage of 100V to obtain regularly arranged liquid crystal molecules, the application time is 0.4s, the maximum The frequency of the AC electric field must be high enough, greater than 60KHz, to keep the pitch gradient constant.

Compared with the traditional wide white fluorescent device, the beneficial effects of the present invention are reflected in:

1. The present invention utilizes a high-voltage DC electric field and a high-frequency AC electric field to generate a cholesteric liquid crystal pitch gradient, and the process is simple and implementable. Fast switching of luminescent colors is achieved through electric field regulation.

2. The white fluorescent color rendering index of the liquid crystal device of the present invention is high, and has great application prospects in the fields of illumination and display.

3. The liquid crystal device of the present invention is different from the LED white light device studied before, and realizes white fluorescence in the cholesteric liquid crystal display.

4. The present invention uses nematic liquid crystal doped with fluorescent material, chiral agent and chiral ions to prepare devices, and the process is simple.

Description of drawings

Fig. 1 is a structural diagram of a white fluorescent cholesteric liquid crystal display device prepared by the present invention.

Fig. 2 is a schematic flow chart of preparing a white fluorescent cholesteric liquid crystal display device according to an embodiment of the present invention.

Fig. 3 is a transmittance curve and a fluorescence curve of a liquid crystal device prepared in an embodiment of the present invention.

detailed description

As shown in FIG. 1 , a white fluorescent cholesteric liquid crystal device based on chiral ions includes two transparent substrate layers 1 and a single liquid crystal layer sandwiched between the two transparent substrate layers. The luminescent material 2 is evenly distributed in the cholesteric liquid crystal, and is distributed in a helical gradient along with the liquid crystal molecules. The liquid crystal layer is a cholesteric liquid crystal 3, which is composed of a nematic liquid crystal doped with a luminescent material, a chiral agent and chiral ions. The cholesteric liquid crystal 3 is distributed in a spiral gradient between the two transparent substrate layers 1 .

The cholesteric liquid crystal 3 is a negative liquid crystal, and the weight of the doped luminescent material is 0.15%-0.25% of the weight of the nematic liquid crystal, and the cholesteric liquid crystal is composed of a nematic liquid crystal doped with a chiral agent and chiral ions 4 The weight of the chiral agent is 4%-25% of the weight of the nematic liquid crystal, and the doped chiral ion is imidazole chiral ion, and its weight is 4%-10% of the weight of the nematic liquid crystal.

A preparation process for a white fluorescent cholesteric liquid crystal device based on chiral ions. Firstly, cholesteric liquid crystals, luminescent materials, chiral agents and chiral ions are mixed and injected into the liquid crystal device between two transparent substrate layers 1. Nematic liquid crystals are mixed with chiral agents and chiral ions to obtain cholesteric liquid crystals. A DC electric field is applied between the two transparent substrate layers, and after stabilization, it is switched to a high-frequency AC electric field to obtain a white fluorescent cholesteric liquid crystal device.

Applying a DC voltage of 100V on the cholesteric liquid crystal induces its pitch gradient distribution, the application time is 3s; and then applying a 100KHz high-frequency AC voltage of 100V to obtain regularly arranged liquid crystal molecules, the application time is 0.4s, the maximum The frequency of the AC electric field must be high enough, greater than 60KHz, to keep the pitch gradient constant.

In the present invention, nematic liquid crystals are doped with luminescent materials, chiral agents and chiral ionic materials, and the pitch gradient distribution of liquid crystals is induced under the action of an electric field to obtain white light-emitting liquid crystal devices. The internal structure of the devices is shown in Figure 1. The prepared liquid crystal device has the advantages of white light emitting performance, high color rendering index and fast adjustment.

The chiral ion-based white fluorescent cholesteric liquid crystal device of the invention is composed of transparent glass substrates parallel to each other and cholesteric liquid crystals with pitch gradient distribution in a liquid crystal cell.

The liquid crystal device of the present invention induces a pitch gradient by a direct current electric field, and then is controlled by a sufficiently high frequency alternating electric field to obtain regular arrangement of liquid crystal molecules.

Example:

1. Preparation of cholesteric liquid crystals

The proportioning ratio of the cholesteric liquid crystal is:

HNG715600-100/S811/CIM/AFAN=79.91%/15.98%/4%/0.11% (wt%).

The HNG715600-100 used is a negative nematic liquid crystal produced by Jiangsu Hecheng Display Technology Co., Ltd.; AFAN is a luminescent material with a chemical formula of S811 is a chiral agent, the chemical formula is CIM is a chiral ion, the chemical formula is

The cholesteric liquid crystal was heated and stirred on a hot stage, the heating time was 30min, and the heating temperature was 95°C.

2. Preparation of liquid crystal devices

The preparation of the device is shown in Figure 2. The above-mentioned cholesteric liquid crystal was injected into a 30 μm liquid crystal cell by the capillary method, a DC voltage of 100 V was applied, and then switched to a high-frequency AC voltage, and the transmittance curve of the device was tested to verify that a white fluorescent cholesteric liquid crystal display device was obtained.

3. Liquid crystal device performance test

The transmittance curve and fluorescence curve of the prepared white fluorescent cholesteric liquid crystal display device are shown in Figure 3, wherein (A) is the transmittance curve of the prepared white fluorescent cholesteric liquid crystal display device. When the pitch is uniformly distributed, it is in the P state (planar texture state), corresponding to the solid line in the figure, and has a relatively narrow reflection band; when the pitch gradient is distributed, it is broadband (broadband display state), corresponding to the dotted line in the figure , with a relatively wide reflection band. Wherein (B) is the fluorescence curve diagram of the prepared white fluorescent cholesteric liquid crystal display device, and the solid line in the figure is P state, has a stronger blue fluorescent peak; Spectral band, high color rendering index.

The internal structure of the white light cholesteric liquid crystal device is shown in Figure 1. Since it can be adjusted by an electric field, the pitch gradient of the cholesteric liquid crystal can be quickly distributed, so that it can quickly switch between blue fluorescence and white fluorescence.

Claims (5)

1. a white fluorescent cholesteric liquid crystal device based on chiral ion, it is characterised in that: by two-layer transparent substrate layer with And the cholesteric crystal layer composition between two-layer transparency carrier.Cholesteric liquid crystal by nematic liquid crystal doping chiral agent and chirality from Son is constituted；Luminescent material is distributed in cholesteric liquid crystal, with Liquid Crystal Molecules Alignment；The pitch of cholesteric liquid crystal is at two transparency carriers Distribution gradient between Ceng.

A kind of white fluorescent cholesteric liquid crystal device based on chiral ion the most according to claim 1, it is characterised in that: When pitch is uniformly distributed, device presents single fluorescent characteristic；And when forming pitch gradient, device fluorescence spectrum broadens, Color rendering index uprises.

A kind of white fluorescent cholesteric liquid crystal device based on chiral ion the most according to claim 1, it is characterised in that: Described cholesteric liquid crystal is negative liquid crystal, the 0.15%-0.25% that luminescent material weight is nematic liquid crystal weight adulterated, gallbladder Steroid phase liquid crystal is made up of nematic liquid crystal doping chiral agent and chiral ion, and chiral agent weight is the 4%-of nematic liquid crystal weight 25%, the chiral ion simultaneously adulterated is imidazole chiral ion, and its weight is the 4%-10% of nematic liquid crystal weight.

4. the preparation technology of a white fluorescent cholesteric liquid crystal device based on chiral ion, it is characterised in that include following step Rapid:

First the mixing of nematic liquid crystal, fluorescent material, chiral agent and chiral ion is injected the two-layer transparency carrier of liquid crystal device Between Ceng, to applying DC electric field between two-layer transparent substrate layer, after stablizing, switch to high-frequency alternating current field, i.e. obtain white glimmering Light cholesteric liquid crystal device.

The preparation technology of a kind of white fluorescent cholesteric liquid crystal device based on chiral ion the most according to claim 4, It is characterized in that: applying size is that the DC voltage of 100V induces the distribution of its pitch gradient on described cholesteric liquid crystal, executes Adding the time is 3s；The 100V high-frequency ac voltage applying 100KHz again obtains the liquid crystal molecule of regular arrangement, application time 0.4s, high-frequency ac electric field frequency must be sufficiently high, more than 60KHz, pitch gradient can be kept constant.