CN106009009A - Preparation method of organic ferroelectric film with high polarization intensity - Google Patents

Abstract

The preparation method of the organic ferroelectric film with high polarization disclosed by the present invention uses PbTiO3 nanosheets and PVDF _- TrFE as the main raw materials, first dissolves PVDF-TrFE in tetrahydrofuran, and then adds an appropriate amount _of PbTiO3 nanosheets to obtain Suspension liquid: PbTiO ₃ nanosheets are uniformly dispersed in the solution by ultrasonic treatment, spin-coated on a clean substrate to form a uniform film by spin-coating, and then heat-treated at 180°C. The preparation process of the invention is simple and the process is easy to control, and the prepared organic ferroelectric thin film has an oriented micro-nano structure, and also has excellent electrical properties, and the residual polarization is as high as 12.4 μC/cm ² .

Description

A kind of preparation method of organic ferroelectric thin film with high polarization

technical field

The invention relates to a method for preparing an organic ferroelectric thin film, belonging to the field of organic ferroelectric polymer materials.

Background technique

Traditional ceramic materials have very high ferroelectric remanent polarization, but the preparation process is complex, brittle and ferroelectric loss is large. Organic polymers are flexible, have low ferroelectric losses, and are easy to process. PVDF-TrFE (polyvinylidene fluoride-trifluoroethylene), as a class of organic ferroelectrics, can be widely used in energy harvesters, pyroelectric infrared detectors and non-volatile memories, etc., with excellent electrical properties and wide applications prospect. Compared with traditional inorganic perovskite phase ferroelectric materials, the remanent polarization of PVDF-TrFE is low (about 6 μC/cm ² ), which limits its application in electronic device materials. -TrFE is modified to improve its electrical properties (dielectric, ferroelectric, piezoelectric, pyroelectric properties, etc.), which can further broaden the application field of PVDF-TrFE.

The spontaneous polarization of PVDF-TrFE is close to 6 μC/cm ² , the ferroelectric coefficient d33 is about -38pm/V at room temperature, and due to its excellent biocompatibility, it has great potential in energy harvesting and biosensing. Great potential application value. At present, the research on the modification of PVDF-TrFE includes nano-confinement method, polar solvent method, template method, epitaxial growth and other methods, but although these methods can control the orientation of the structure to a certain extent, their electrical properties have not improved. a lot of.

Contents of the invention

The object of the present invention is to provide a method for preparing an organic ferroelectric thin film with high polarization.

The method for preparing an organic ferroelectric thin film with high polarization of the present invention comprises the following steps:

1) Place the substrate in deionized water, acetone, and absolute ethanol in order to ultrasonically clean and dry;

2) Dissolving PVDF-TrFE in tetrahydrofuran to obtain a tetrahydrofuran solution of PVDF-TrFE, the mass/volume ratio of PVDF-TrFE to tetrahydrofuran is 1/20;

₃ ) Place the _PbTiO nanosheets in the tetrahydrofuran solution of PVDF-TrFE obtained in step 2), the mass/volume ratio of the PbTiO nanosheets to the THF solution of PVDF-TrFE is 0.2%-5.0%, stir to obtain a suspension liquid;

4) Ultrasonic treatment of the suspension obtained in step 3) to uniformly disperse the PbTiO ₃ nanosheets in the tetrahydrofuran solution of PVDF-TrFE, and after standing for 20-40 min, spin-coat it onto a clean surface On the substrate, a thin film is obtained;

5) Vacuum-dry the film obtained in step 4), and heat-treat at 180°C for 0.5-2h.

In the present invention, the substrate may be an ITO or Si substrate.

In the present invention, the purity of tetrahydrofuran, acetone and absolute ethanol is not lower than chemical purity.

In the present invention, the PbTiO ₃ nanosheets have a single crystal single domain structure.

PbTiO ₃ nanosheets with single crystal and single domain structure can be obtained by referring to the preparation method of the doctoral thesis of Zhejiang University - "Growth Regulation, Microstructure and Properties of Perovskite Ferroelectric Oxide Nanostructures, authored by Chao Chunying".

The preparation process of the present invention is simple, and the process is easy to control. The thickness of the film is related to the standing time and spin coating parameters. The prepared organic ferroelectric film has a thickness of 0.8 μm-1 μm, has an oriented micro-nano structure, and also has excellent Electrical properties, remanent polarization up to 12.4μC/cm ² .

Description of drawings

Fig. 1 is the grazing incidence XRD pattern of the organic ferroelectric thin film prepared by example 1;

Fig. 2 is the GIWAXS figure of the organic ferroelectric film prepared by example 1;

Fig. 3 is the AFM figure of the organic ferroelectric film prepared by example 1;

FIG. 4 is a diagram of the ferroelectric properties of the organic ferroelectric thin film prepared in Example 1. FIG.

detailed description

Below in conjunction with embodiment further illustrate the present invention.

Example 1

1) The ITO substrate was ultrasonically cleaned in deionized water, acetone, and absolute ethanol in sequence, and then dried by infrared lamps;

2) Dissolve 1 g of PVDF-TrFE in 20 mL of tetrahydrofuran to obtain a tetrahydrofuran solution of PVDF-TrFE;

₃ ) Place 0.002g of PbTiO3 nanosheets in the solution obtained in step ₂ ), the mass/volume ratio of PbTiO3 nanosheets and PVDF-TrFE tetrahydrofuran solution is 0.2%, stir to obtain a suspension;

4) Ultrasonic treatment of the suspension obtained in step 3), so that the PbTiO ₃ nanosheets were uniformly dispersed in the tetrahydrofuran solution of PVDF-TrFE, and after standing for 20 min, it was spin-coated (1500 rpm, 30 s) onto a clean surface. On the ITO substrate, a thin film is obtained;

5) The film obtained in step 4) was vacuum-dried and heat-treated at 180° C. for 1 hour.

The thickness of the organic ferroelectric thin film prepared in this example is 0.8 μm, its grazing incidence XRD spectrum is shown in Figure 1, and the GIWAXS diagram is shown in Figure 2. It can be seen from Figure 1 and Figure 2 that the organic ferroelectric thin film has an oriented micro-nano structure . The AFM diagram is shown in Fig. 3, and it can be seen from Fig. 3 that the obtained organic ferroelectric thin film is composed of well-crystallized rod-shaped crystals. Tested by Radiant's ferroelectric tester, the ferroelectric performance diagram is shown in Figure 4, from which it can be seen that the remanent polarization is 12.4μC/cm ² .

Example 2

The specific process steps are the same as in Example 1, the difference is that in step 3) the PbTiO ₃ nanosheets weighed are 0.005 g, and the mass/volume ratio of PbTiO ₃ nanosheets and PVDF-TrFE tetrahydrofuran solution is 0.5%, and step 4) statically The setting time is 40 min, and the heat treatment time of step 5) is 0.5 hour. The remanent polarization of the organic ferroelectric thin film prepared in this example is 10 μC/cm ² .

Example 3

The specific process steps are the same as in Example 1, the difference is that the Si substrate is used, and the PbTiO nanosheets weighed in step ₃ ) are 0.0527g, and the mass/volume ratio of the _PbTiO nanosheets and the tetrahydrofuran solution of PVDF-TrFE is 5.0% , step 4) standing time is 30 min, step 5) heat treatment time is 2 hours, the remanent polarization of the organic ferroelectric thin film prepared in this example is 8 μC/cm ² .

Claims (4)

1. an Organic Iron conductive film preparation method with high polarization intensity, it is characterised in that comprise the following steps:

1) Substrate is sequentially placed into ultrasonic cleaning in deionized water, acetone, dehydrated alcohol, dries；

2) PVDF-TrFE being dissolved in oxolane, obtains the tetrahydrofuran solution of PVDF-TrFE, PVDF-TrFE is 1/20 with the mass/volume ratio of oxolane；

3) By PbTiO₃Nanometer sheet is placed in step 2) in the tetrahydrofuran solution of the PVDF-TrFE of gained, PbTiO₃The mass/volume of nanometer sheet and the tetrahydrofuran solution of PVDF-TrFE ratio for 0.2%-5.0%, stirring, obtains suspension；

4) Sonicating step 3) suspension of gained, make PbTiO₃Nanometer sheet is evenly dispersed in the tetrahydrofuran solution of PVDF-TrFE, after standing 20-40 min, uses the method for spin coating to be spun in the substrate of cleaning, obtains thin film；

5) Film vacuum obtained by step 4) is dried, in 180 DEG C of heat treatment 0.5-2h.

The preparation method of the Organic Iron conductive film with high polarization intensity the most according to claim 1, is characterized in that described substrate is ITO or Si substrate.

The preparation method of the Organic Iron conductive film with high polarization intensity the most according to claim 1, is characterized in that described PbTiO₃Nanometer sheet is monocrystalline one-domain structure.

The preparation method of the Organic Iron conductive film with high polarization intensity the most according to claim 1, is characterized in that described oxolane, acetone, the purity of dehydrated alcohol are all not less than chemical pure.