Cu2O-ZnO doped P (VDF-TrFE) high-voltage electric film and preparation method thereof

Abstract

The invention belongs to the technical field of piezoelectric materials, and relates to a Cu2O-ZnO doped P (VDF-TrFE) high-voltage electric film and a preparation method thereof. The preparation method comprises the following steps: preparing the P (VDF-TrFE)-based nanofiber membrane of which the surface is uniformly distributed with ZnO seeds, growing the ZnO nanorod array on the P (VDF-TrFE)-based nanofiber membrane by adopting a hydrothermal method, and then growing Cu2O particles on the ZnO nanorod array by adopting the hydrothermal method, thereby obtaining the Cu2O-ZnO doped P (VDF-TrFE) high-voltage electric film. The ZnO nanorod array grows in an oriented manner, the p-n heterojunction is constructed, and the interface combination is optimized, so that the problems of insufficient beta-phase induction, remarkable potential shielding effect and poor interface synergy in the prior art are systematically solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of piezoelectric materials, and relates to a Cu2O-ZnO-doped P(VDF-TrFE) high piezoelectric film and a preparation method thereof. BACKGROUND

[0002] P(VDF-TrFE) based piezoelectric films have a wide application prospect in the field of flexible electronics due to their excellent flexibility and piezoelectric properties. To further improve their piezoelectric properties, researchers have tried to introduce Cu2O and ZnO nanomaterials as modifiers. The introduction methods mainly include multilayer composite structure preparation, 3D printing technology and vapor deposition method, but these methods have significant defects in practical application.

[0003] The multilayer composite structure preparation method attempts to improve the piezoelectric properties by stacking materials through hot pressing or bonding process. However, the interface between different material layers is only combined by physical action, and the interface bonding force is weak, which is easy to cause delamination and peeling in the use process. This leads to insufficient interface synergistic effect of ZnO nanorods and P(VDF-TrFE) matrix, and the ZnO nanorods are difficult to deform synchronously with the polymer during stress transfer, the ion charge separation efficiency is low, and the piezoelectric performance is limited. In addition, the ZnO nanorods are unevenly dispersed in the composite layer, which cannot effectively induce P(VDF-TrFE) to form a high dipole moment β phase crystal type, limiting the further improvement of piezoelectric properties.

[0004] The 3D printing technology attempts to achieve uniform distribution of nanomaterials through structural design by embedding Cu2O-ZnO dopants into P(VDF-TrFE) film during the printing process. However, for ZnO nanorods, the layer thickness precision of 3D printing cannot meet the needs of its oriented growth, resulting in disordered arrangement and uneven size of ZnO nanorods. This not only weakens the induction effect of ZnO nanorods on β phase by spontaneous polarization, but also aggravates the potential shielding effect due to random contact of ZnO nanorods, which cancels out the piezoelectric potential through tunneling effect of free carriers, resulting in significant decrease in piezoelectric properties. In addition, the solvent system available for printing is limited, and ZnO nanorods are prone to agglomeration, which further deteriorates the material dispersion and interface bonding force.

[0005] The gas deposition method deposits ZnO / Cu2O to the surface of P(VDF-TrFE) through physical or chemical vapor deposition technology, and attempts to improve the piezoelectric performance through surface modification. However, it is difficult to accurately control the orientation and spacing of ZnO nanorods in the deposition process, and the nanoscale contact leads to strong carrier tunneling effect, and the piezoelectric performance is significantly inhibited. At the same time, the deposition layer and the polymer matrix are only combined through van der Waals force, and lack an active charge separation mechanism (such as a p-n heterojunction), and the stress-induced charge recombination rate is high, and the piezoelectric output stability is poor.

[0006] In summary, the prior art has significant defects in the interface bonding strength, nanomaterial dispersibility, orientation control and charge separation efficiency in the method of introducing Cu2O and ZnO into P(VDF-TrFE) based piezoelectric thin film. These defects limit the further improvement of piezoelectric performance, and new modification strategies need to be developed to overcome the limitations of the prior art. SUMMARY

[0007] The purpose of the present application is to solve the problems existing in the prior art, and to provide a Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film and a preparation method thereof.

[0008] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0009] A preparation method of a Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film, after preparing a P(VDF-TrFE) based nanofiber film with uniform distribution of ZnO seeds, ZnO nanorod arrays are grown on the P(VDF-TrFE) based nanofiber film by hydrothermal method, and Cu2O particles are grown on the ZnO nanorod arrays by hydrothermal method, to obtain the Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film.

[0010] The Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film of the present application has excellent piezoelectric performance, and the reasons are as follows:

[0011] (1) When ZnO nanorod arrays are grown on the P(VDF-TrFE) based nanofiber film by hydrothermal method, ZnO has a hexagonal wurtzite structure, which has non-central symmetry. The Zn 2+ and O 2- ions are ordered arranged along the c-axis direction, forming an inherent dipole moment, which gives the ZnO nanorod a significant spontaneous polarization characteristic. In the process of spontaneous polarization, the ZnO nanorod accumulates positive charge at one end and negative charge at the other end, and the two opposite polarity charges will in turn induce the P(VDF-TrFE) based nanofiber film to form more β phase.

[0012] P(VDF-TrFE) has multiple crystal phases (such as α phase, β phase, γ phase), among which the β phase is a fully anti-conformation (TTTT conformation), the molecular chain is arranged regularly, and the dipole moment direction of carbon-fluorine bond is consistent, so that it has a very high dipole moment. Dipole moment is a physical quantity to measure the strength of molecular polarity, and the high dipole moment of the β phase means that the molecular polarity is stronger, and the response to external electric field or mechanical stress is more sensitive. When subjected to mechanical stress, the molecular chain of the β phase is more prone to orientation change, resulting in stronger polarization response, leading to more significant charge separation and higher piezoelectric output. In contrast, other crystal phases have relatively disordered molecular chain arrangement and inconsistent dipole moment direction, and have weaker response to external stimuli and lower piezoelectric effect.

[0013] (2) P(VDF-TrFE) based nanofiber membrane and ZnO nanorod produce synergistic piezoelectric enhancement effect: when subjected to stress, the ZnO nanorod deflects and slides with each other, intensifying the synergistic deformation of the ZnO nanorod and the P(VDF-TrFE) based nanofiber membrane, enhancing the ion charge separation, and thus improving the potential and output of the external circuit.

[0014] (3) When the ZnO nanorod contacts at the nanoscale, the free carriers will transfer between the nanorods through the tunneling effect. When the polar surface of the ZnO nanorod is subjected to stress, a pressure potential will be generated along the c-axis of the nanorod, and the induced electric field will further drive the electron tunneling, offsetting the piezoelectricity. This phenomenon is called potential shielding effect, which is the main reason for the decline of piezoelectric performance. The present application grows Cu2O particles on the ZnO nanorod to construct a p-n heterojunction (n-type ZnO / p-type Cu2O), effectively inhibiting the potential shielding effect, and the specific mechanism is as follows:

[0015] When the p-type semiconductor (Cu2O particles) contacts with the n-type semiconductor (ZnO nanorod), due to the difference in carrier concentration, a built-in electric field (direction from n-type to p-type) is formed at the interface. The built-in electric field can block the movement of free carriers, slow down the shielding speed of piezoelectric polarization, and at the same time promote the movement of electrons and holes in opposite directions, realize the effective separation of photo-generated carriers, reduce the recombination of carriers in ZnO, prolong the carrier lifetime and improve the transmission efficiency. In addition, the introduction of p-type semiconductor changes the energy band structure of n-type semiconductor, forming a heterojunction structure conducive to carrier separation and transmission, further improving the output voltage and current density.

[0016] Cu2O as a narrow direct band gap semiconductor (Eg=2.1eV), its conduction band than the cathode of ZnO conduction band more, conducive to the effective transfer of electrons. ZnO and Cu2O interface of the electron and hole diffusion forming depletion region and built-in electric field (Ebi), further promote the separation and collection of piezoelectric induced charge, reduce the complex, thus inhibiting the shielding effect and enhance the piezoelectric output. From the energy band arrangement, ZnO and Cu2O form type II heterojunction (ZnO conduction band is lower than Cu2O conduction band, valence band offset), carrier separation mechanism is: piezoelectric potential driven ZnO electron transfer to Cu2O conduction band, while forming a hole potential barrier between ZnO and Cu2O valence band, reduce the complex, improve the charge separation efficiency and short circuit current (Isc).

[0017] As a preferred technical solution:

[0018] The preparation method of the Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film as described above, the preparation process of the P(VDF-TrFE) based nanofiber film uniformly distributed with ZnO seeds on the surface is as follows: after configuring electrospinning solution containing ZnO@CTAB nanoparticles and P(VDF-TrFE) (polyvinylidene fluoride-trifluoroethylene) at the same time, electrospinning is carried out, and the P(VDF-TrFE) based nanofiber film uniformly distributed with ZnO seeds on the surface is obtained; the thickness of the P(VDF-TrFE) based nanofiber film uniformly distributed with ZnO seeds on the surface is 0.124-0.164mm.

[0019] The ZnO@CTAB nanoparticles are ZnO nanoparticles coated with CTAB (hexadecyl trimethyl ammonium bromide), and the use of CTAB (hexadecyl trimethyl ammonium bromide) to coat the ZnO nanoparticles can improve the dispersibility of the ZnO nanoparticles in the nanofiber film, so that the ZnO seeds are more uniformly distributed on the surface of the nanofiber film, which is conducive to the subsequent growth of ZnO nanorod array on the P(VDF-TrFE) based nanofiber film.

[0020] The preparation method of the Cu2O-ZnO-doped P(VDF-TrFE) high piezoelectric film as described above, and the preparation process of the ZnO@CTAB nanoparticles is as follows: zinc nitrate hexahydrate and CTAB (cetyltrimethylammonium bromide) are dissolved in ethanol, and then sodium hydroxide aqueous solution is added, and then the mixture is reacted at 45-70°C for 0.5-3h, and then ultrasonic treatment is performed for 5-15min using a pointed ultrasonic device, and then post-treatment is performed (washed with ethanol, centrifuged three times at 2000rpm, and dried in a vacuum oven at 70°C for 6h), and the ZnO@CTAB nanoparticles are obtained, wherein the concentration of the sodium hydroxide aqueous solution is 0.05-0.2mol / L, the volume ratio of the sodium hydroxide aqueous solution to ethanol is 1:1-2, and the mass-volume ratio of zinc nitrate hexahydrate, CTAB and ethanol is 1.2-1.8g:0.3-0.6g:60-150mL.

[0021] The preparation method of the Cu2O-ZnO-doped P(VDF-TrFE) high piezoelectric film as described above, and the concentration of P(VDF-TrFE) in the electrospinning solution is 10-15wt%, and the concentration of ZnO@CTAB nanoparticles is 1-10wt%.

[0022] The preparation method of the Cu2O-ZnO-doped P(VDF-TrFE) high piezoelectric film as described above, and the process parameters of electrospinning include: needle type 24G, electrospinning solution injection rate 1-1.5mL / h, voltage difference between needle tip and collector 12-18kV, distance between needle tip and collector 15-30cm, and roller rotation speed 120-200r / min.

[0023] The preparation method of the Cu2O-ZnO-doped P(VDF-TrFE) high piezoelectric film as described above, and the process for growing ZnO nanorod arrays on the P(VDF-TrFE)-based nanofiber film by hydrothermal method is as follows: the P(VDF-TrFE)-based nanofiber film is immersed in a first hydrothermal reaction solution, and then hydrothermal reaction is performed at 70-100°C for 1-3h, and then post-treatment is performed (washed with deionized water), wherein the first hydrothermal reaction solution contains 35-60mM zinc nitrate hexahydrate and 25-60mM hexamethylenetetramine.

[0024] The preparation method of the Cu2O-ZnO-doped P(VDF-TrFE) high piezoelectric film as described above, the process of growing Cu2O particles on the ZnO nanorod array by a hydrothermal method is as follows: the P(VDF-TrFE) based nanofiber film with the surface growing ZnO nanorod array is immersed into a second hydrothermal reaction solution, and after hydrothermal reaction at 120-180 DEG C for 60-90 min, post-treatment is carried out (first ultrasonic cleaning with distilled water and anhydrous ethanol for 5 min, and then drying in a vacuum oven at 30 DEG C for 3 h), wherein the second hydrothermal reaction solution contains 0.002-0.005 M Cu(CH3COO)2·H2O and 0.28-0.4 M triethanolamine.

[0025] The application further provides a Cu2O-ZnO-doped P(VDF-TrFE) high piezoelectric film, which is prepared by the preparation method of the Cu2O-ZnO-doped P(VDF-TrFE) high piezoelectric film according to any one of the above, and has a longitudinal piezoelectric coefficient of 28-64.4 pC / N, an output current of 34-90 nA, and an output voltage of 18.6-42 V.

[0026] Advantages:

[0027] (1) The application grows Cu2O particles on the ZnO nanorod array to construct a p-n heterojunction (n-type ZnO / p-type Cu2O), utilizes the built-in electric field in the interface to block the movement of free carriers, slows down the speed of piezoelectric polarization shielding, and reduces the recombination of carriers, so that the potential shielding effect can be effectively inhibited.

[0028] (2) The application utilizes the spontaneous polarization characteristics of the ZnO nanorod to induce P(VDF-TrFE) to form a high-dipole-moment β phase, and the ZnO nanorod and the P(VDF-TrFE) based nanofiber film produce synergistic deformation under stress, so that the ion charge separation is enhanced, and the piezoelectric response is further improved.

[0029] (3) The application combines electrospinning and hydrothermal method to uniformly grow ZnO nanorod array and Cu2O particles on the surface of the P(VDF-TrFE) based nanofiber film to form a three-level composite structure (P(VDF-TrFE) / ZnO / Cu2O), and the process has strong controllability, ensures the orientation consistency and material stability of the heterojunction interface, and avoids the problems of weak combination of multi-layer composite interfaces and uneven dispersion of nanoparticles in the traditional method.

[0030] (4) The Cu2O-ZnO-doped P(VDF-TrFE) high piezoelectric film prepared by the application has good flexibility and mechanical properties, can adapt to complex mechanical deformation, has good stability under different environmental conditions, and is suitable for various application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 Schematic of fiber morphology in P(VDF-TrFE) based nanofiber film with uniform distribution of ZnO seeds on the surface of Example 1;

[0032] Figure 2 Schematic of fiber morphology in P(VDF-TrFE) based nanofiber film with ZnO nanorod array grown on the surface of Example 1;

[0033] Figure 3 Schematic of fiber morphology in Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film of Example 1;

[0034] Figure 4 SEM image of P(VDF-TrFE) based nanofiber film with ZnO nanorod array grown on the surface of Example 2;

[0035] Figure 5 and Figure 6 SEM image of Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film of Example 5;

[0036] Figure 7 Beta phase content map of P(VDF-TrFE) based nanofiber film with uniform distribution of ZnO seeds on the surface of Example 1;

[0037] Figure 8 Induced charge vs. time curve of Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film of Example 5 at different test frequencies;

[0038] Figure 9 Output current test results of Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film of Example 5;

[0039] Figure 10 Output voltage test results of Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film of Example 5;

[0040] Figure 11 SEM image of Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film of Example 6;

[0041] Figure 12 SEM image of Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film of Example 1. DETAILED DESCRIPTION

[0042] The application will be further described below in connection with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not used to limit the scope of the application. Furthermore, it should be understood that after reading the content of the application, those skilled in the art can make various modifications or changes to the application, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] The following are the test methods of the relevant performance indicators in each embodiment:

[0044] Longitudinal piezoelectric coefficient: the sample is placed in a longitudinal piezoelectric box, and pressure is manually applied (initially 2N, maximum 20N), the pressure signal is connected to the oscilloscope CH1 channel through the force sensor, and the test frequency is 100Hz; the sample is fixed on the pressure spring, and the output electric signal is connected to the oscilloscope CH2 channel, and finally the longitudinal piezoelectric coefficient is calculated by the ratio of the CH2 output electric signal to the CH1 pressure signal.

[0045] Output current and output voltage: the high-voltage piezoelectric film is fixed between the two sliders of the stepping motor, one end of the slider is fixed, and the other end is controlled by the motor to move at a speed of v=9.5mm / s and a moving distance of Δd=20.0mm to perform transverse reciprocating motion, so that the generator experiences cyclic compression-tension deformation to induce electric signal output, thereby measuring the output current and output voltage.

[0046] The parameter range such as "the concentration of the sodium hydroxide aqueous solution is 0.05-0.2mol / L" recorded in the application is an "effective implementation interval" summarized based on a large number of previous variable screening experiments. In the following embodiments, many parameters (such as the concentration of the sodium hydroxide aqueous solution) remain the same, and this design is not a limitation on the protection scope of the application. Those skilled in the art can adjust any related parameters based on the parameter ranges defined in the application, and similar piezoelectric performance effects can be achieved, and these adjustments do not exceed the protection scope defined in the claims of the application.

[0047] Example 1

[0048] A preparation method of a Cu2O-ZnO doped P(VDF-TrFE) high-voltage piezoelectric film, the specific steps are as follows:

[0049] (1) Preparation of raw materials;

[0050] Zinc nitrate hexahydrate;

[0051] CTAB;

[0052] Ethanol;

[0053] Sodium hydroxide aqueous solution: the concentration is 0.1mol / L;

[0054] Organic solvent: composed of DMF and acetone with a volume ratio of 1:2;

[0055] P(VDF-TrFE): the manufacturer is Kunshan Hais Electronic Co., Ltd., the molar ratio of VDF to TrFE is 70:30;

[0056] The first hydrothermal reaction solution is composed of zinc nitrate hexahydrate, methenamine, and deionized water, the concentration of zinc nitrate hexahydrate is 50mM, and the concentration of methenamine is 50mM;

[0057] The second hydrothermal reaction solution is composed of Cu(CH3COO)2·H2O, triethanolamine, and deionized water, the concentration of Cu(CH3COO)2·H2O is 0.003M, and the concentration of triethanolamine is 0.36M;

[0058] (2) Preparation of ZnO@CTAB nanoparticles;

[0059] After dissolving zinc nitrate hexahydrate and CTAB in ethanol, add sodium hydroxide aqueous solution to it, then react at 55℃ for 1h, ultrasonic for 10min, after treatment, ZnO@CTAB nanoparticles are obtained; wherein the volume ratio of sodium hydroxide aqueous solution to ethanol is 1:1, the mass volume ratio of zinc nitrate hexahydrate, CTAB and ethanol is 1.48g:0.43g:100mL;

[0060] (3) Configuration of electrospinning solution;

[0061] First, dissolve ZnO@CTAB nanoparticles in a reagent bottle containing organic solvent, ultrasonic for 30min, then add P(VDF-TrFE) to it, shake quickly until the white agglomerates in the bottle disappear, then seal the bottle mouth with plastic wrap, put it into a 50℃ constant temperature magnetic water bath, magnetic stirring for 6h, finally put it into an ultrasonic cleaning machine to remove bubbles for 30min, and get the electrospinning solution;

[0062] In the electrospinning solution, the concentration of P(VDF-TrFE) is 13.5wt%, and the concentration of ZnO@CTAB nanoparticles is 1.69wt%;

[0063] (4) Electrospinning of electrospinning solution, to get P(VDF-TrFE) based nanofiber membrane with a thickness of 0.124mm and uniform distribution of ZnO seeds on the surface (the fiber morphology is shown in Figure 1 );

[0064] The process parameters of electrospinning are as follows: needle type 24G, electrospinning solution injection rate 1.32mL / h, voltage difference between needle tip and collector 16kV, distance between needle tip and collector 20cm, and drum rotating speed 140r / min;

[0065] (5) The P(VDF-TrFE) based nanofiber membrane is immersed into the first hydrothermal reaction solution, and after hydrothermal reaction at 90℃ for 2h, post-treatment is performed, to obtain the P(VDF-TrFE) based nanofiber membrane with ZnO nanorod arrays grown on the surface (wherein the fiber morphology is as shown in Figure 2 The test shows that the longitudinal piezoelectric coefficient of the P(VDF-TrFE) based nanofiber membrane with ZnO nanorod arrays grown on the surface is 40pC / N, the output current is 46nA, and the output voltage is 21V;

[0066] (6) The P(VDF-TrFE) based nanofiber membrane with ZnO nanorod arrays grown on the surface is immersed into the second hydrothermal reaction solution, and after hydrothermal reaction at 160℃ for 60min, post-treatment is performed, to obtain the Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film (wherein the fiber morphology is as shown in Figure 3 ).

[0067] The longitudinal piezoelectric coefficient of the finally obtained Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film is 60pC / N, the output current is 72nA, and the output voltage is 34V.

[0068] The β phase content (89%) of the P(VDF-TrFE) based nanofiber membrane with ZnO nanorod arrays grown on the surface prepared in the embodiment is as shown in Figure 7 Compared with the pure P(VDF-TrFE) based nanofiber membrane, the β phase content is increased by 15%; wherein the difference between the preparation process of the pure P(VDF-TrFE) based nanofiber membrane and steps (1)-(4) of the embodiment is that no ZnO@CTAB nanoparticles are added in step (3).

[0069] Embodiment 2

[0070] A preparation method of a Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film, and the specific steps are as follows:

[0071] (1) Preparation of raw materials;

[0072] Zinc nitrate hexahydrate;

[0073] CTAB;

[0074] Ethanol;

[0075] Sodium hydroxide aqueous solution: concentration is 0.1mol / L;

[0076] Organic solvent: composed of DMF and acetone in a volume ratio of 1:2;

[0077] P(VDF-TrFE): the manufacturer is Kunshan Hais Electronic Co., Ltd., the molar ratio of VDF and TrFE is 70:30;

[0078] The first hydrothermal reaction solution is composed of zinc nitrate hexahydrate, hexamethylenetetramine and deionized water, the concentration of zinc nitrate hexahydrate is 50 mM, and the concentration of hexamethylenetetramine is 50 mM;

[0079] The second hydrothermal reaction solution is composed of Cu(CH3COO)2·H2O, triethanolamine and deionized water, the concentration of Cu(CH3COO)2·H2O is 0.003 M, and the concentration of triethanolamine is 0.36 M;

[0080] (2) Preparation of ZnO@CTAB nanoparticles;

[0081] After dissolving zinc nitrate hexahydrate and CTAB in ethanol, sodium hydroxide aqueous solution is added, and then the reaction is carried out at 60℃ for 1.5h, and then ultrasonic vibration is carried out for 5min, and after treatment, ZnO@CTAB nanoparticles are obtained; wherein the volume ratio of sodium hydroxide aqueous solution to ethanol is 1:1.2, and the mass-volume ratio of zinc nitrate hexahydrate, CTAB and ethanol is 1.5g:0.4g:90mL;

[0082] (3) Configuration of electrospinning solution;

[0083] First, the ZnO@CTAB nanoparticles are dissolved in a reagent bottle containing an organic solvent, and ultrasonic vibration is carried out for 30min, then P(VDF-TrFE) is added, the bottle is quickly shaken until the white agglomerates in the bottle disappear, then the bottle opening is sealed with a plastic wrap, and placed in a 50℃ constant temperature magnetic water bath, and magnetically stirred for 6h, and finally placed in an ultrasonic cleaning machine for 30min to remove bubbles, and an electrospinning solution is obtained;

[0084] In the electrospinning solution, the concentration of P(VDF-TrFE) is 14wt%, and the concentration of ZnO@CTAB nanoparticles is 2wt%;

[0085] (4) Electrospinning of electrospinning solution to obtain P(VDF-TrFE) based nanofiber membrane with a thickness of 0.153mm and ZnO seeds uniformly distributed on the surface;

[0086] The process parameters of electrospinning are as follows: needle type 24G, electrospinning solution injection rate 1.4mL / h, voltage difference between needle tip and collector 17kV, distance between needle tip and collector 25cm, and drum rotating speed 160r / min;

[0087] (5) The P(VDF-TrFE) based nanofiber membrane is immersed into the first hydrothermal reaction solution, and after hydrothermal reaction at 80°C for 1h and post-treatment, a P(VDF-TrFE) based nanofiber membrane with ZnO nanorod arrays grown on the surface is obtained (SEM is shown in Figure 4 The test shows that the longitudinal piezoelectric coefficient of the P(VDF-TrFE) based nanofiber membrane with ZnO nanorod arrays grown on the surface is 25pC / N, the output current is 37nA, and the output voltage is 16V.

[0088] (6) The P(VDF-TrFE) based nanofiber membrane with ZnO nanorod arrays grown on the surface is immersed into the second hydrothermal reaction solution, and after hydrothermal reaction at 140°C for 70min and post-treatment, a Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film is obtained.

[0089] The longitudinal piezoelectric coefficient of the finally obtained Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film is 45pC / N, the output current is 54nA, and the output voltage is 23.5V.

[0090] Example 3

[0091] A preparation method of a Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film, and the specific steps are as follows:

[0092] (1) Preparation of raw materials;

[0093] Zinc nitrate hexahydrate;

[0094] CTAB;

[0095] Ethanol;

[0096] Sodium hydroxide aqueous solution: the concentration is 0.1mol / L;

[0097] Organic solvent: composed of DMF and acetone in a volume ratio of 1:2;

[0098] P(VDF-TrFE): the manufacturer is Kunshan Hais Electronic Co., Ltd., and the molar ratio of VDF to TrFE is 70:30;

[0099] The first hydrothermal reaction solution is composed of zinc nitrate hexahydrate, hexamethylene tetramine and deionized water, and the concentration of zinc nitrate hexahydrate is 50mM and the concentration of hexamethylene tetramine is 25mM;

[0100] The second hydrothermal reaction solution is composed of Cu(CH3COO)2·H2O, triethanolamine and deionized water, and the concentration of Cu(CH3COO)2·H2O is 0.003M and the concentration of triethanolamine is 0.36M;

[0101] (2) Preparation of ZnO@CTAB nanoparticles;

[0102] After dissolving zinc nitrate hexahydrate and CTAB in ethanol, an aqueous sodium hydroxide solution was added thereto, and then reacted at 60℃ for 2h, and then ultrasonic for 8min, and then obtained ZnO@CTAB nanoparticles after post-processing; wherein the volume ratio of the aqueous sodium hydroxide solution to ethanol was 1:1.5, and the mass-volume ratio of zinc nitrate hexahydrate, CTAB and ethanol was 1.2g:0.35g:80mL;

[0103] (3) Preparation of electrospinning solution;

[0104] First, the ZnO@CTAB nanoparticles were dissolved in a reagent bottle containing an organic solvent, and then ultrasonic for 30min, and then P(VDF-TrFE) was added thereto, and then quickly shaken until the white agglomerates in the bottle disappeared, and then the bottle opening was closed with a plastic wrap, and then placed in a 50℃ constant temperature magnetic water bath, and then magnetically stirred for 6h, and then placed in an ultrasonic cleaning machine for 30min to remove bubbles, and then obtained the electrospinning solution;

[0105] In the electrospinning solution, the concentration of P(VDF-TrFE) was 12wt%, and the concentration of ZnO@CTAB nanoparticles was 4wt%;

[0106] (4) Electrospinning of the electrospinning solution to obtain a P(VDF-TrFE) based nanofiber membrane with a thickness of 0.148mm and a surface uniformly distributed with ZnO seeds;

[0107] The process parameters of electrospinning were as follows: needle type 24G, electrospinning solution injection rate 1.5mL / h, voltage difference between needle tip and collector 14kV, distance between needle tip and collector 15cm, and drum rotation speed 180r / min;

[0108] (5) The P(VDF-TrFE) based nanofiber membrane was immersed in a first hydrothermal reaction solution, and then hydrothermally reacted at 75℃ for 1.5h, and then post-processed to obtain a P(VDF-TrFE) based nanofiber membrane with a surface grown with ZnO nanorod arrays, and tests showed that the longitudinal piezoelectric coefficient of the P(VDF-TrFE) based nanofiber membrane with a surface grown with ZnO nanorod arrays was 22pC / N, the output current was 28nA, and the output voltage was 14V;

[0109] (6) The P(VDF-TrFE) based nanofiber membrane with a surface grown with ZnO nanorod arrays was immersed in a second hydrothermal reaction solution, and then hydrothermally reacted at 120℃ for 90min, and then post-processed to obtain a Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film.

[0110] The longitudinal piezoelectric coefficient of the Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film prepared finally is 32 pC / N, the output current is 38 nA, and the output voltage is 19.8 V.

[0111] Example 4

[0112] A preparation method of a Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film, and the specific steps are as follows:

[0113] (1) Preparation of raw materials;

[0114] Zinc nitrate hexahydrate;

[0115] CTAB;

[0116] Ethanol;

[0117] Sodium hydroxide aqueous solution: the concentration is 0.1 mol / L;

[0118] Organic solvent: composed of DMF and acetone in a volume ratio of 1:2;

[0119] P(VDF-TrFE): the manufacturer is Kunshan Hais Electronic Co., Ltd., and the molar ratio of VDF to TrFE is 70:30;

[0120] First hydrothermal reaction solution: composed of zinc nitrate hexahydrate, methenamine, and deionized water, the concentration of zinc nitrate hexahydrate is 50 mM, and the concentration of methenamine is 25 mM;

[0121] Second hydrothermal reaction solution: composed of Cu(CH3COO)2·H2O, triethanolamine, and deionized water, the concentration of Cu(CH3COO)2·H2O is 0.003 M, and the concentration of triethanolamine is 0.36 M;

[0122] (2) Preparation of ZnO@CTAB nanoparticles;

[0123] After dissolving zinc nitrate hexahydrate and CTAB in ethanol, sodium hydroxide aqueous solution is added, and then the mixture is reacted at 65℃ for 3h, and then ultrasonic treatment is performed for 15 min. After post-treatment, ZnO@CTAB nanoparticles are obtained; wherein the volume ratio of sodium hydroxide aqueous solution to ethanol is 1:1.5, and the mass-volume ratio of zinc nitrate hexahydrate, CTAB, and ethanol is 1.7g:0.5g:110mL;

[0124] (3) Configuration of electrospinning solution;

[0125] First, the ZnO@CTAB nanoparticles are dissolved in a reagent bottle containing an organic solvent, ultrasonic vibration for 30 min, then P(VDF-TrFE) is added, shake quickly until the white agglomerates in the bottle disappear, then use the fresh-keeping film to seal the bottle mouth, put it into a constant temperature magnetic water bath at 50℃, magnetic stirring for 6h, finally put it into an ultrasonic cleaner to remove bubbles for 30 min, to get the electrospinning solution;

[0126] In the electrospinning solution, the concentration of P(VDF-TrFE) is 15wt%, and the concentration of ZnO@CTAB nanoparticles is 6wt%;

[0127] (4) The electrospinning solution is electrospun to obtain a P(VDF-TrFE) based nanofiber membrane with a thickness of 0.164mm and a uniform distribution of ZnO seeds on the surface;

[0128] The process parameters of electrospinning are as follows: needle type 24G, electrospinning solution injection rate 1.5mL / h, voltage difference between needle tip and collector 18kV, distance between needle tip and collector 30cm, and drum rotation speed 180r / min;

[0129] (5) The P(VDF-TrFE) based nanofiber membrane is immersed in the first hydrothermal reaction solution, and after hydrothermal reaction at 100℃ for 2h, post-processing is carried out to obtain a P(VDF-TrFE) based nanofiber membrane with ZnO nanorod array grown on the surface. Tests show that the longitudinal piezoelectric coefficient of the P(VDF-TrFE) based nanofiber membrane with ZnO nanorod array grown on the surface is 23pC / N, the output current is 32nA, and the output voltage is 17.3V;

[0130] (6) The P(VDF-TrFE) based nanofiber membrane with ZnO nanorod array grown on the surface is immersed in the second hydrothermal reaction solution, and after hydrothermal reaction at 180℃ for 80min, post-processing is carried out to obtain a Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film.

[0131] The longitudinal piezoelectric coefficient of the finally prepared Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film is 28pC / N, the output current is 34nA, and the output voltage is 18.6V.

[0132] Example 5

[0133] A preparation method of a Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film, and the difference from Example 1 is only that the hydrothermal reaction time in step (6) is 80min.

[0134] The finally prepared Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric thin film (SEM as shown in Figure 5and Figure 6 The longitudinal piezoelectric coefficient of the Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film prepared in this embodiment is 64.4 pC / N, the output current is 90 nA (as shown in Figure 9 The output voltage is 42 V (as shown in Figure 10 The output voltage is 42 V (as shown in

[0135] The induced charge-time curve of the Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film prepared in this embodiment at different test frequencies is shown in Figure 8 The induced charge of the Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film prepared in this embodiment is 118 pC at a test frequency of 100 Hz, which is 3.47 times that of the pure P(VDF-TrFE) based nanofiber film.

[0136] The difference between the preparation process of the pure P(VDF-TrFE) based nanofiber film described in this embodiment and steps (1)-(4) of this embodiment is that no ZnO@CTAB nanoparticles are added in step (3).

[0137] Embodiment 6

[0138] A preparation method of a Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film, and the difference between this embodiment and embodiment 1 is that the hydrothermal reaction time in step (6) is 40 min.

[0139] The longitudinal piezoelectric coefficient of the Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric film prepared in this embodiment is 54.5 pC / N, the output current is 63 nA, and the output voltage is 23 V.

[0140] The SEMs of the Cu2O-ZnO doped P(VDF-TrFE) high piezoelectric films prepared in embodiments 6, 1 and 5 are shown in Figure 11 , Figure 12 , Figure 5 As can be seen from the figures, when the hydrothermal reaction time is 40 min, no obvious Cu2O particles are found on the surface of the ZnO nanorod; when the hydrothermal reaction time is 60 min, spherical Cu2O particles with a particle size of about 200 nm appear at the top of the ZnO nanorod, showing selective growth; when the hydrothermal reaction time is 80 min, the loading density of Cu2O particles is significantly improved, forming a uniform ZnO / Cu2O heterojunction structure without damaging the P(VDF-TrFE) based nanofiber film matrix.

Claims

1. A method for preparing a Cu₂O-ZnO-doped P(VDF-TrFE) high-voltage electric thin film, characterized in that, After preparing a P(VDF-TrFE)-based nanofiber film with ZnO seeds uniformly distributed on its surface, a ZnO nanorod array was grown on the P(VDF-TrFE)-based nanofiber film using a hydrothermal method. Then, Cu2O particles were grown on the ZnO nanorod array using a hydrothermal method to obtain a Cu2O-ZnO-doped P(VDF-TrFE) high-voltage electric thin film.

2. The method for preparing a Cu₂O-ZnO-doped P(VDF-TrFE) high-voltage electric thin film according to claim 1, characterized in that, The preparation process of P(VDF-TrFE)-based nanofiber membrane with ZnO seeds uniformly distributed on the surface is as follows: after preparing an electrospinning solution containing ZnO@CTAB nanoparticles and P(VDF-TrFE), electrospinning is performed to obtain P(VDF-TrFE)-based nanofiber membrane with ZnO seeds uniformly distributed on the surface; the thickness of the P(VDF-TrFE)-based nanofiber membrane with ZnO seeds uniformly distributed on the surface is 0.124-0.164 mm.

3. The method for preparing a Cu₂O-ZnO-doped P(VDF-TrFE) high-voltage electric thin film according to claim 2, characterized in that, The preparation process of ZnO@CTAB nanoparticles is as follows: zinc nitrate hexahydrate and CTAB are dissolved in ethanol, sodium hydroxide aqueous solution is added, and the mixture is reacted at 45-70℃ for 0.5-3 h, followed by sonication for 5-15 min. After post-treatment, ZnO@CTAB nanoparticles are obtained. The concentration of sodium hydroxide aqueous solution is 0.05-0.2 mol / L, the volume ratio of sodium hydroxide aqueous solution to ethanol is 1:1-2, and the mass-volume ratio of zinc nitrate hexahydrate, CTAB, and ethanol is 1.2-1.8 g:0.3-0.6 g:60-150 mL.

4. The method for preparing a Cu2O-ZnO-doped P(VDF-TrFE) high-voltage electric thin film according to claim 2, characterized in that, In the electrospinning solution, the concentration of P(VDF-TrFE) is 10-15 wt%, and the concentration of ZnO@CTAB nanoparticles is 1-10 wt%.

5. The method for preparing a Cu₂O-ZnO-doped P(VDF-TrFE) high-voltage electric thin film according to claim 2, characterized in that, The electrospinning process parameters include: needle type 24G, electrospinning solution spraying rate 1-1.5mL / h, voltage difference between needle tip and collector 12-18kV, distance between needle tip and collector 15-30cm, and roller speed 120-200r / min.

6. The method for preparing a Cu₂O-ZnO-doped P(VDF-TrFE) high-voltage electric thin film according to claim 1, characterized in that, The process of growing ZnO nanorod arrays on P(VDF-TrFE)-based nanofiber membranes using a hydrothermal method is as follows: the P(VDF-TrFE)-based nanofiber membrane is immersed in a first hydrothermal reaction solution and hydrothermally reacted at 70-100℃ for 1-3 hours, followed by post-treatment. The first hydrothermal reaction solution contains 35-60 mM zinc nitrate hexahydrate and 25-60 mM hexamethylenetetramine.

7. The method for preparing a Cu₂O-ZnO-doped P(VDF-TrFE) high-voltage electric thin film according to claim 1, characterized in that, The process of growing Cu2O particles on ZnO nanorod arrays using a hydrothermal method is as follows: The P(VDF-TrFE)-based nanofiber film on which the ZnO nanorod array is grown is immersed in a second hydrothermal reaction solution and hydrothermally reacted at 120-180℃ for 60-90 min, followed by post-treatment. The second hydrothermal reaction solution contains 0.002-0.005M Cu(CH3COO)2·H2O and 0.28-0.4M triethanolamine.

8. A Cu₂O-ZnO-doped P(VDF-TrFE) high-voltage thin film, characterized in that, The Cu2O-ZnO-doped P(VDF-TrFE) high-voltage thin film was prepared using the method described in any one of claims 1 to 7. The longitudinal piezoelectric coefficient was 28-64.4 pC / N, the output current was 34-90 nA, and the output voltage was 18.6-42 V.

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