CN109461810B - Ultrafast electron transmission piezoelectric energy harvester and preparation method thereof - Google Patents

Ultrafast electron transmission piezoelectric energy harvester and preparation method thereof Download PDF

Info

Publication number
CN109461810B
CN109461810B CN201811353045.1A CN201811353045A CN109461810B CN 109461810 B CN109461810 B CN 109461810B CN 201811353045 A CN201811353045 A CN 201811353045A CN 109461810 B CN109461810 B CN 109461810B
Authority
CN
China
Prior art keywords
piezoelectric
quantum dot
piezoelectric element
layer
type
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201811353045.1A
Other languages
Chinese (zh)
Other versions
CN109461810A (en
Inventor
周静
王志青
陈文�
刘曰利
沈杰
陈巧
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wuhan University of Technology WUT
Original Assignee
Wuhan University of Technology WUT
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wuhan University of Technology WUT filed Critical Wuhan University of Technology WUT
Priority to CN201811353045.1A priority Critical patent/CN109461810B/en
Publication of CN109461810A publication Critical patent/CN109461810A/en
Application granted granted Critical
Publication of CN109461810B publication Critical patent/CN109461810B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H10N30/304—Beam type
    • H10N30/306—Cantilevers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/802—Drive or control circuitry or methods for piezoelectric or electrostrictive devices not otherwise provided for

Abstract

The invention discloses an ultrafast electron transfer piezoelectric energy harvester and a preparation method thereof. The direct rectification of the alternating current electric energy generated by the piezoelectric element layer is converted into direct current electric energy and the direct current electric energy can be transmitted out very quickly without additionally arranging an external energy acquisition circuit, so that the loss of the electric energy is greatly reduced, the integration and the miniaturization of devices are facilitated, and the energy acquisition and conversion efficiency of the piezoelectric energy harvesting device is improved.

Description

Ultrafast electron transmission piezoelectric energy harvester and preparation method thereof
Technical Field
The invention relates to the technical field of energy collection, in particular to an ultrafast electron transfer piezoelectric energy harvester and a preparation method thereof.
Background
The mechanical energy-electric energy conversion process based on the piezoelectric effect can convert mechanical energy which is not utilized in the environment, such as noise, vibration, human body movement and the like, into electric energy. Compared with other environmental energy collection modes, the piezoelectric type energy collection can continuously, stably and economically collect environmental vibration energy, has the advantages of high energy density, simple structure, small heating, no electromagnetic interference and the like, can replace an electrochemical battery to become a new self-powered power supply for equipment of the Internet of things, sensor network nodes, wearable or implanted electronic equipment and the like, and arouses the common attention of different subject fields of material science, information, automatic control and the like.
Piezoelectric energy harvesters can utilize mechanical vibration to generate electrical energy. Researchers strive to optimize the electromechanical structure and design the necessary external charge transfer circuitry to provide high power and charge transfer output for the battery. The complex deformation of the mechanical structure causes charges with opposite polarities to appear on the same surface of the piezoelectric material, so that the positive charges and the negative charges are easy to recombine, and the high-performance piezoelectric energy harvester can be obtained only by effectively separating the positive charges and the negative charges and quickly conducting the positive charges and the negative charges to an external circuit. However, the charge generated by piezoelectricity is generally short lived, while the bulk material is bulky. In general, the distance from generation to annihilation is less than the radius of the bulk material, so a large portion of the generated charge is recombined before it is transferred to an external circuit, resulting in loss of electrical energy. In the quantum dot material, because the quantum dot has extremely small volume, the pressure dot charges have enough service life and are transmitted to the surface of the quantum dot, so that the positive and negative charges are effectively separated and are quickly transmitted to an external circuit, and the loss of electric energy can be greatly reduced.
When the piezoelectric energy harvester works normally, the quantum dots can be matched with the energy levels of a plurality of piezoelectric materials because the band structure of the quantum dots can be regulated and controlled by the size, so that the quantum dots become an excellent charge transport material. The N-type semiconductor quantum dot transmission material has the advantages that the N-type semiconductor quantum dot transmission material has quantum dot ultra-fast electron conduction, and meanwhile, donor impurities in the N-type semiconductor quantum dot transmission material can provide more electrons for a conduction band, so that the electron concentration is remarkably increased in the carrier transmission process, the transmission rate of negative charges (electrons) in the N-type semiconductor quantum dot transmission material is far greater than that of positive charges (holes), and the transmission rate of the positive charges (holes) can be ignored. The macroscopic expression is that negative charges (electrons) generated on the surface of the piezoelectric material are transmitted to the metal electrode through the quantum dot material, positive charges (holes) cannot be transmitted through the quantum dot material, the quantum dot material directly replaces the effect of an external charge transmission circuit, the self-charge transmission of alternating current generated by the piezoelectric energy harvester is realized, and the energy collection and conversion efficiency is also improved.
Disclosure of Invention
The technical problem to be solved by the invention is to provide an ultrafast electron-transfer piezoelectric energy harvester and a preparation method thereof, aiming at the defects in the prior art, so that alternating current electric energy generated by a piezoelectric element layer is directly rectified and converted into direct current electric energy and can be output ultrafast, external charge transfer current is not required to be additionally arranged, the electric energy loss is greatly reduced, the integration and miniaturization of devices are facilitated, and the energy acquisition and conversion efficiency of the piezoelectric energy harvester is improved.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the utility model provides an ultrafast electron transfer piezoelectricity energy harvester, includes quantum dot charge transfer piezoelectricity energy harvesting board and fixing device, and quantum dot charge transfer piezoelectricity energy harvesting board is connected with fixing device, and quantum dot charge transfer piezoelectricity energy harvesting board includes base plate, piezoelectric element layer and N type quantum dot self-charge transport layer, and piezoelectric element layer and N type quantum dot self-charge transport layer lay in proper order on the base plate.
According to the technical scheme, one end of the quantum dot charge transmission piezoelectric energy harvesting plate is connected with the fixing device, and the other end of the quantum dot charge transmission piezoelectric energy harvesting plate is suspended to form the cantilever beam type vibration supporting structure.
According to the technical scheme, the N-type quantum dot charge transport layer is connected with an external energy storage device.
According to the technical scheme, the piezoelectric element layer is one or the combination of any more of piezoelectric crystal, piezoelectric ceramic, piezoelectric film, piezoelectric polymer and piezoelectric composite material.
According to the technical scheme, the piezoelectric element layer is a PZT piezoelectric film.
According to the technical scheme, the N-type quantum dot charge transmission layer and the piezoelectric element layer need to meet the following conditions:
Figure BDA0001865365990000021
and is
Figure BDA0001865365990000022
Self-charge transmission is formed between the N-type quantum dot self-charge transmission layer and the piezoelectric element layer, wherein the N-type quantum dot self-charge transmission layer is in contact with the piezoelectric element layer to cause energy band structure deviation between materials, and generate potential difference VDIs the contact potential difference, V, between the self-charge transport layer and the piezoelectric element layerD1Is the potential difference at the self-charge transport layer of the N-type quantum dot, VD2For potential differences at the layer of the piezoelectric element, ND1Is the carrier concentration of the self-charge transport layer of the N-type quantum dot, ND2Is the carrier concentration of the piezoelectric element layer,1is the dielectric constant of the N-type quantum dots from the charge transport layer,2the dielectric constant of the piezoelectric element layer.
According to the technical scheme, the N-type quantum dot self-charge transport layer is an N-type CdS QD hole transport layer.
According to the technical scheme, the substrate is made of Pt/TiO2/SiO2/Si。
The method for preparing the ultrafast electron transfer piezoelectric energy harvester comprises the following steps:
1) preparing a PZT piezoelectric film on a substrate by adopting a magnetron sputtering method;
2) preparing a quantum dot precursor solution by adopting a one-pot method;
3) spin-coating the quantum dot precursor solution on the PZT piezoelectric film to form an N-type quantum dot self-charge transport layer;
4) one end of the substrate is connected with the fixing device to form the cantilever beam type supporting structure.
According to the technical scheme, in the step 2), the specific process for preparing the quantum dot precursor solution by adopting the one-pot method comprises the following steps:
A) adding a certain amount of cadmium oxide, thiourea, octadecene, glycerol and oleic acid into a container;
B) introducing argon into the container, and heating and stirring the solution in the container to obtain CdS stock solution;
C) transferring the CdS stock solution into a separating funnel, and separating an upper oil phase after an octadecene phase and a glycerol phase are separated;
D) putting the obtained oil phase in a beaker, adding n-hexane with the volume 2 times that of the oil phase, and stirring the mixture by a glass rod until the solution is uniformly mixed;
E) continuously adding acetone, stirring until flocculent precipitate is not separated out and the solution is in a suspension state;
F) subpackaging the suspension into a centrifuge, carrying out centrifugal separation on the suspension, keeping the precipitate after the separation is finished, and adding n-hexane for dissolving;
G) and repeating the steps C) to F) for multiple times until the CdS quantum dots are dispersed in n-hexane.
According to the technical scheme, in the step A), the weighing amounts of the cadmium oxide, the thiourea, the octadecene, the glycerol and the oleic acid are respectively 0.128g, 0.038g, 8mL, 10mL and 2mL, and the volume of the container is 50 mL.
According to the technical scheme, in the step F), the rotating speed of centrifugal separation of the suspension by the centrifugal machine is 2200 to 2800r/min, and the centrifugal separation time is 15 to 25 min.
The invention has the following beneficial effects:
through the direct laminating on N type quantum dot charge transfer layer and piezoelectric element layer, the realization turns into direct current electric energy and can super fast output with the direct rectification of the alternating current electric energy that the piezoelectric element layer produced, need not to adorn outside charge transmission again, has greatly reduced the loss of electric energy, and the integration and the miniaturization of the device of being convenient for have improved the energy acquisition conversion efficiency of piezoelectricity energy harvesting device.
Drawings
FIG. 1 is a schematic structural diagram of an ultrafast electron transfer piezoelectric energy harvester according to an embodiment of the present invention;
FIG. 2 is a partial schematic view of FIG. 1 at K under tension;
FIG. 3 is a partial schematic view of K of FIG. 1 under compressive stress;
FIG. 4 is a schematic diagram of the power generation of the quantum dot charge transfer piezoelectric energy trapping plate in the embodiment of the invention when the plate vibrates;
FIG. 5 is a positive and negative charge distribution diagram of a quantum dot charge transfer piezoelectric energy trapping plate when the plate is not vibrated according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of an energy level structure of an N-type charge transport piezoelectric energy harvester according to an embodiment of the invention;
in the figure, 1-substrate, 2-piezoelectric element layer, 3-N type quantum dot self-charge transport layer, 4-fixing device, 5-quantum dot charge transport piezoelectric energy trapping plate, 6-positive charge, 7-negative charge and 8-Pt electrode.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and examples.
Referring to fig. 1 to 6, an ultrafast electron transfer piezoelectric energy harvester according to an embodiment of the present invention includes a quantum dot charge transfer piezoelectric energy harvesting plate 5 and a fixing device 4, the quantum dot charge transfer piezoelectric energy harvesting plate 5 is connected to the fixing device 4, the quantum dot charge transfer piezoelectric energy harvesting plate 5 includes a substrate 1, a piezoelectric element layer 2 and an N-type quantum dot self-charge transfer layer 3, and the piezoelectric element layer 2 and the N-type quantum dot self-charge transfer layer 3 are sequentially laid on the substrate 1; the quantum dot charge transfer piezoelectric energy harvesting plate 5 vibrates with the fixing device 4 as a supporting point to form amplitude, the piezoelectric element layer 2 generates electric energy by vibration, the vibration energy is converted into alternating current electric energy, and the N-type quantum dots are attached to the piezoelectric element layer 2 from the charge transfer layer 3, directly convert the alternating current electric energy into direct current electric energy and output the direct current electric energy to the outside.
Furthermore, one end of the quantum dot charge transfer piezoelectric energy harvesting plate 5 is connected with the fixing device 4, and the other end of the quantum dot charge transfer piezoelectric energy harvesting plate 5 is suspended to form a cantilever beam type vibration supporting structure.
Furthermore, the quantum dot charge transfer piezoelectric energy harvesting plate 5 and the fixing device 4 can be connected in a manner of forming a cantilever beam type vibration support structure, a simple beam type vibration support structure, a circular vibration support structure, a cymbal type vibration support structure and a Rainbow type vibration support structure.
Further, the N-type quantum dots are connected with an external energy storage device from the charge transport layer 3.
Further, the external energy storage device is an energy storage capacitor, and is used for storing direct current electric energy and supplying power to the direct current electric appliance.
Further, the piezoelectric element layer 2 is one or a combination of any several of piezoelectric crystals, piezoelectric ceramics, piezoelectric films, piezoelectric polymers and piezoelectric composite materials.
Further, the piezoelectric element layer 2 is a PZT piezoelectric thin film.
Further, PZT is lead zirconate titanate, which is a piezoelectric material.
Further, the structure of the piezoelectric element in the piezoelectric element layer 2 mainly has a rectangular, triangular, square, circular, and the like structure.
Further, the operation modes of the piezoelectric element layer 2 include a d33 mode in which the strain is parallel to the direction of the electric field, a d31 mode in which the strain is perpendicular to the direction of the electric field, and a d15 mode in which shear strain is generated when the polarization direction is perpendicular to the direction of the electric field.
Further, the N-type quantum dot self-charge transport layer 3 and the piezoelectric element layer 2 need to satisfy the following conditions:
Figure BDA0001865365990000041
and is
Figure BDA0001865365990000042
The self-charge transmission is formed between the N-type quantum dots 3 and the piezoelectric element layer 2, wherein the contact between the N-type quantum dots 3 and the piezoelectric element layer 2 causes the energy band structure between the materials to shift, and a potential difference V is generatedDIs the contact potential difference, V, between the N-type quantum dot self-charge transport layer 3 and the piezoelectric element layer 2D1Is the potential difference at the self-charge transport layer 3 of the N-type quantum dots, VD2Is the potential difference at the piezoelectric element layer 2, ND1Is the carrier concentration of the N-type quantum dots from the charge transport layer 3, ND2Is the carrier concentration of the piezoelectric element layer 2,1is the dielectric constant of the N-type quantum dots from the charge transport layer 3,2the dielectric constant of the piezoelectric element layer 2; the electrochemical potential matching of the N-type quantum dot self-charge transport layer 3 and the piezoelectric element layer 2 and the energy band structure matching of the N-type quantum dot self-charge transport layer 3 and the piezoelectric element layer 2 are realized.
Further, the N-type quantum dot self-charge transport layer 3 is an N-type CdS QD hole transport layer, and QDs are abbreviations of english names of quantum dots, namely quantum dots.
Further, the material of the substrate 1 is Pt/TiO2/SiO2/Si。
The method for preparing the ultrafast electron transfer piezoelectric energy harvester comprises the following steps:
1) preparing a PZT piezoelectric film on the substrate 1 by adopting a magnetron sputtering method;
2) preparing a quantum dot precursor solution by adopting a one-pot method;
3) spin coating the precursor solution of the quantum dots on the PZT piezoelectric film to form an N-type quantum dot self-charge transport layer 3;
4) one end of the substrate 1 is connected to the fixing device 4 to form an cantilever beam type support structure.
Further, in the step 2), the specific process for preparing the quantum dot precursor solution by adopting the one-pot method comprises the following steps:
A) adding a certain amount of cadmium oxide, thiourea, octadecene, glycerol and oleic acid into a container;
B) introducing argon into the container, and heating and stirring the solution in the container to obtain CdS stock solution;
C) transferring the CdS stock solution into a separating funnel, and separating an upper oil phase after an octadecene phase and a glycerol phase are separated;
D) putting the obtained oil phase in a beaker, adding n-hexane with the volume 2 times that of the oil phase, and stirring the mixture by a glass rod until the solution is uniformly mixed;
E) continuously adding acetone, stirring until flocculent precipitate is not separated out and the solution is in a suspension state;
F) subpackaging the suspension into a centrifuge, carrying out centrifugal separation on the suspension, keeping the precipitate after the separation is finished, and adding n-hexane for dissolving;
G) and repeating the steps C) to F) for multiple times until the CdS quantum dots are dispersed in n-hexane.
Further, the quantum dot precursor solution contains CdS quantum dots (namely N-type CdS quantum dots), and after the quantum dot precursor solution is coated on the PZT piezoelectric film in a rotating mode and solidified, the CdS quantum dots form an N-type quantum dot self-charge transmission layer 3.
In step A), the weighed amounts of cadmium oxide, thiourea, octadecene, glycerol and oleic acid were 0.128g, 0.038g, 8mL, 10mL and 2mL, respectively, and the volume of the container was 50 mL.
Further, in the step F), the rotation speed of the centrifugal separation of the suspension by the centrifugal machine is 2600r/min, and the centrifugal separation time is 20 min.
In an embodiment of the present invention, the preparation of the CdS QD-PZT piezoelectric energy trapping material is used as an objective in the present embodiment, and the preparation of the CdS QD-PZT piezoelectric energy trapping material by the present invention specifically includes the following processes:
1. by magnetron sputtering on Pt/TiO2/SiO2Preparing a PZT piezoelectric film on a Si substrate, wherein an MSP-620 type high-vacuum magnetron sputtering instrument is adopted as the instrument, and sputtering parameters are set as follows: the substrate temperature is 100 ℃, the sputtering power is 100W, Ar, the flow rate is 80sccm, the O2 flow rate is 0, the gas pressure is 0.6Pa, the sputtering time is 5000s, and the annealing is carried out for 30min at 700 ℃.
2. Preparing an N-type CdS QD electron transport layer by adopting a one-pot method: 0.128g of cadmium oxide and 0.038g of thiourea were weighed in each case, 8mL of octadecene, 10mL of glycerol and 2mL of oleic acid were weighed in, the above reactants were mixed in a 50mL three-necked flask at room temperature, and the heating and magnetic stirring procedure was switched on with introduction of nitrogen. Controlling experimental parameters such as reaction temperature, reaction time, precursor proportion and the like, and preparing CdS QDs with different sizes;
the CdS quantum dot purification process comprises transferring CdS stock solution into a separating funnel, and separating an upper oil phase after an octadecylene phase and a glycerol phase are separated. The obtained oil phase is placed in a beaker, n-hexane with the volume 2 times that of the oil phase is added, and the mixture is stirred by a glass rod until the solution is uniformly mixed. Then, acetone is continuously added, and the mixture is stirred until flocculent precipitates are not separated out and the solution is in a suspension state. Subpackaging the suspension into a centrifuge, setting the rotation speed at 2600r/min, and centrifuging for 20min under the condition; and after the separation is finished, keeping the precipitate, adding n-hexane for dissolving, repeating the purification process for 2-3 times, and finally dispersing the CdS quantum dots in the n-hexane.
Assembling the CdS QD-PZT piezoelectric energy trapping material: and (3) spin-coating the prepared CdS QD quantum dot precursor solution on a piezoelectric element (PZT) by adopting a spin-coating method. The optimal spin coating speed of the quantum dots is 4000 rpm; the optimal annealing time of the quantum dots is 3 min; the optimal concentration of the quantum dot precursor solution is 10 mg/mL.
4. Assembling the piezoelectric energy harvester: the prepared CdS QD-PZT piezoelectric energy trapping material is assembled into a cantilever beam structure, a Pt electrode is prepared by magnetron sputtering, and the sputtering process comprises the following steps: the substrate temperature is room temperature, the sputtering power is 100W, Ar, the flow rate is 80sccm and O2The flow rate is 0, the air pressure is 0Pa,The sputtering time was 300 s. And connecting the external energy storage device with the cantilever beam by using a lead.
And constructing an energy band structure of the CdSQDs-PZT piezoelectric energy trapping material, as shown in FIG. 3. E in the figureg,PZT，Eg,CdSRespectively representing the forbidden band widths of the two materials; phiPZT，ΦCdSRespectively representing the energy difference between the vacuum electron energy level and the Fermi energy level of the two materials, namely the work function of electrons; chi shapePZT，χCdSThe energy difference between the vacuum electron energy level and the conduction band bottom, namely the electron affinity energy. The electron affinity of PZT and CdS QDs adopts chi PZT of 3.5eV and chi CdS of 3eV respectively, the Fermi level of PZT is assumed to be at the central position of the band gap, and the work function of the corresponding PZT is about phiPZTPhi 5.34eV, work function of CdS QDs is phiCdS3.58 eV. The band gaps of PZT and CdS QDs are respectively Eg,PZT3.4eV and Eg,CdS2.25 eV. Assuming that the CdS QD-PZT interface has no defects, a built-in potential difference V can be generated at the interface due to the difference of the work functions of PZT and CdS QDs under an ideal conditionDThe built-in potential difference is the difference between the PZT and CdS QDs work functions, i.e. VD＝ΦPZT-ΦCdS＝1.76eV。
The calculation model assumes:
1. the piezoelectric heterojunction has an abrupt depletion layer;
2. at two ends of the depletion layer, the carrier distribution meets the Boltzmann statistical distribution;
3. the current of electrons and holes passing through the depletion layer is constant, and the generation and recombination of carriers in the depletion layer are not considered;
4. the minority carrier concentration injected is much less than the majority carrier concentration at equilibrium, so the small injection assumption can be adopted.
5. The lattice mismatch at the interface is not considered.
The carrier concentration at the equilibrium interface is now calculated as shown in fig. 3. Take the valence band (Ev) as an example. Taking the potential at PZT as zero (hereinafter referred to as p region), the potential V at one point x in the barrier region(x)Positive values. The closer to the point of CdS (hereinafter referred to as n region), the higher the potential, the barrier region boundaryxnN-zone of a potential of at most Δ EVIn the figure, xn，xpRespectively n-region and p-region barrier region boundaries. For electrons, the corresponding potential energy of the p region is higher than that of the n region
Figure BDA0001865365990000061
High q Δ EV. The potential energy at the point X in the potential barrier region is E(x)＝-qΔE(x)Higher than n region by q Δ EV-qΔE(x)。
Since the low barrier peak is formed at this time, the electron flow of the heterojunction is mainly determined by the diffusion mechanism, and the diffusion model is adopted for processing, in FIG. 3, the barrier height from the conduction band bottom of the n-type region to the conduction band bottom of the P-type region is qVD1+qVD2+ΔEc＝qVD+ΔEcThe relationship between the minority carrier concentration n10 in the P-type semiconductor and the majority carrier concentration n20 in the n-type semiconductor can be obtained as
Figure BDA0001865365990000071
Taking x as 0 at the interface, and setting the barrier boundaries of the P region and the n region as x as-x when a forward voltage V is applied to the heterojunction1And x ═ x2P-type semiconductor-x1Has a minority carrier concentration of n1(-x1) N if generation and recombination of carriers in the barrier region are neglected1(-x1) And n20In a relationship of
Figure BDA0001865365990000072
In a steady state situation, the continuity equation for the injected minority carrier motion in a P-type semiconductor is:
Figure BDA0001865365990000073
its general solution is
Figure BDA0001865365990000074
In the formula, Dn1And Ln1The diffusion coefficient and diffusion length of the P-type region minority carrier electrons, respectively. When the boundary condition x is ═ infinity, n1(-∞)＝n10And a can be obtained as 0. When x is ═ x1Then get solved
Figure BDA0001865365990000075
Substituting A with 0 and B in the formula to obtain
Figure BDA0001865365990000076
Thereby obtaining the diffusion current density of the carrier
Figure BDA0001865365990000077
The above equation is the electron diffusion current density injected from the n-type region into the P-type region, and the hole diffusion current density injected from the P-type region into the n-type region is calculated below. It can be seen from the figure that the hole barrier height from the P-zone valence band top to the n-zone valence band top is Δ Ev
So that the concentration p of minority carrier holes in the n-type semiconductor is at thermal equilibrium20The hole concentration of the P-type semiconductor is increased as follows:
Figure BDA0001865365990000078
when a forward voltage V is applied to the heterojunction, the hole barrier is lowered to Δ Ev-V, x ═ x in the n region2The hole concentration of which is increased to
Figure BDA0001865365990000081
The same as before, solving the diffusion equation and applying the boundary conditions, the result is
Figure BDA0001865365990000082
Thereby obtaining hole diffusion current density
Figure BDA0001865365990000083
In the formula, Dp2And Lp2Respectively representing the diffusion coefficient and diffusion length of holes in the n-type region.
The total current density through the hetero Pn junction when voltage V is applied is given by:
Figure BDA0001865365990000084
according to the CdS QD-PZT heterostructure, voltage is generated on one side of a piezoelectric material, positive voltage is generated, positive current is generated in the heterostructure, when negative voltage is generated, potential barriers of an interface are reduced due to the existence of CdS quantum dots, and charges can be rapidly transmitted under negative pressure.
When in use
Figure BDA0001865365990000085
Then the heterostructure realizes the rapid transmission of charges;
wherein the content of the first and second substances,
Figure BDA0001865365990000086
ND1is the carrier concentration of N type CdS QDs, ND2In order to the PZT carrier concentration,1is the dielectric constant of N-type CdS QDs,2for PZT dielectric constant, QD is an acronym for the english name of quantum dot, i.e., quantum dot.
Therefore, the CdS QD-PZT piezoelectric energy trapping material has good electron transmission performance.
In summary, by utilizing the semiconductor characteristics of the quantum dot material, the quantum dot and the high-performance piezoelectric element are compounded to obtain the brand-new self-charge-transfer piezoelectric energy harvesting material, so that the power consumption generated by an external charge transfer circuit can be greatly reduced, the integration and miniaturization of the device are facilitated, and the energy collection and conversion efficiency of the piezoelectric energy harvesting device is improved.
The above is only a preferred embodiment of the present invention, and certainly, the scope of the present invention should not be limited thereby, and therefore, the present invention is not limited by the scope of the claims.

Claims (8)

1. An ultrafast electron transfer piezoelectric energy harvester is characterized by comprising a quantum dot charge transfer piezoelectric energy harvesting plate and a fixing device, wherein the quantum dot charge transfer piezoelectric energy harvesting plate is connected with the fixing device and comprises a substrate, a piezoelectric element layer and an N-type quantum dot charge transfer layer, and the piezoelectric element layer and the N-type quantum dot charge transfer layer are sequentially laid on the substrate;
the N-type quantum dot charge transport layer and the piezoelectric element layer need to satisfy the following conditions:
Figure FDA0002471313490000011
and is
Figure FDA0002471313490000012
The N-type quantum dots form ultra-fast charge transmission between the charge transmission layer and the piezoelectric element layer, wherein the contact of the N-type quantum dots and the piezoelectric element layer causes the energy band structure between materials to shift, and generates a potential difference VDIs the contact potential difference, V, between the self-charge transport layer and the piezoelectric element layerD1Is the potential difference at the self-charge transport layer of the N-type quantum dot, VD2For potential differences at the layer of the piezoelectric element, ND1Is the carrier concentration of the self-charge transport layer of the N-type quantum dot, ND2Is the carrier concentration of the piezoelectric element layer,1is the dielectric constant of the N-type quantum dots from the charge transport layer,2is the dielectric constant of the piezoelectric element layer;
the N-type quantum dot charge transport layer is an N-type CdS QD hole transport layer.
2. The ultrafast electron transfer piezoelectric energy harvester of claim 1, wherein one end of the quantum dot charge transfer piezoelectric energy harvesting plate is connected to the fixing device, and the other end of the quantum dot charge transfer piezoelectric energy harvesting plate is suspended to form a cantilever beam type vibration support structure.
3. The ultrafast electron-transporting piezoelectric energy harvester of claim 1, wherein the N-type quantum dot charge transport layer is connected to an external energy storage device.
4. The ultrafast electron transfer piezoelectric energy harvester of claim 1, wherein the piezoelectric element layer is one or a combination of any several of piezoelectric crystals, piezoelectric ceramics, piezoelectric films, piezoelectric polymers and piezoelectric composites.
5. The ultrafast electron transfer piezoelectric harvester of claim 4, wherein the piezoelectric element layer is a PZT piezoelectric film.
6. The ultrafast electron transfer piezoelectric energy harvester of claim 1, wherein the substrate is made of Pt/TiO2/SiO2/Si。
7. The method of preparing the ultrafast electron transfer piezoelectric energy harvester of claim 1, comprising the steps of:
1) preparing a PZT piezoelectric film on a substrate by adopting a magnetron sputtering method;
2) preparing a quantum dot precursor solution by adopting a one-pot method;
3) spin coating the quantum dot precursor solution on the PZT piezoelectric film to form an N-type quantum dot charge transport layer;
4) one end of the substrate is connected with the fixing device to form the cantilever beam type supporting structure.
8. The preparation method according to claim 7, wherein in the step 2), the specific process for preparing the quantum dot precursor solution by using the one-pot method comprises the following steps:
A) adding a certain amount of cadmium oxide, thiourea, octadecene, glycerol and oleic acid into a container;
B) introducing argon into the container, and heating and stirring the solution in the container to obtain CdS stock solution;
C) transferring the CdS stock solution into a separating funnel, and separating an upper oil phase after an octadecene phase and a glycerol phase are separated;
D) putting the obtained oil phase in a beaker, adding n-hexane with the volume 2 times that of the oil phase, and stirring the mixture by a glass rod until the solution is uniformly mixed;
E) continuously adding acetone, stirring until flocculent precipitate is not separated out and the solution is in a suspension state;
F) subpackaging the suspension into a centrifuge, carrying out centrifugal separation on the suspension, keeping the precipitate after the separation is finished, and adding n-hexane for dissolving;
G) and repeating the steps C) to F) for multiple times until the CdS quantum dots are dispersed in n-hexane.
CN201811353045.1A 2018-11-14 2018-11-14 Ultrafast electron transmission piezoelectric energy harvester and preparation method thereof Active CN109461810B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201811353045.1A CN109461810B (en) 2018-11-14 2018-11-14 Ultrafast electron transmission piezoelectric energy harvester and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201811353045.1A CN109461810B (en) 2018-11-14 2018-11-14 Ultrafast electron transmission piezoelectric energy harvester and preparation method thereof

Publications (2)

Publication Number Publication Date
CN109461810A CN109461810A (en) 2019-03-12
CN109461810B true CN109461810B (en) 2020-08-25

Family

ID=65610376

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201811353045.1A Active CN109461810B (en) 2018-11-14 2018-11-14 Ultrafast electron transmission piezoelectric energy harvester and preparation method thereof

Country Status (1)

Country Link
CN (1) CN109461810B (en)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009131636A2 (en) * 2008-04-14 2009-10-29 Rolls-Royce Corporation Manufacture of field activated components by stereolithography
WO2018085936A1 (en) * 2016-11-10 2018-05-17 Polyvalor, Limited Partnership Piezoelectric composite, ink and ink cartridge for 3d printing, bifunctional material comprising the piezoelectric composite, manufacture and uses thereof
CN106910838B (en) * 2017-03-31 2018-10-09 华南理工大学 A kind of perovskite luminescent device and preparation method thereof based on piezoelectric film

Also Published As

Publication number Publication date
CN109461810A (en) 2019-03-12

Similar Documents

Publication Publication Date Title
Lee et al. All-in-one energy harvesting and storage devices
JP6383702B2 (en) Method for manufacturing a nanowire structure
US20080230120A1 (en) Photovoltaic device with nanostructured layers
JP6049271B2 (en) Electric energy generator
Pradel et al. Optoelectronic properties of solution grown ZnO np or pn core–shell nanowire arrays
Jia et al. Cadmium sulfide as an efficient electron transport material for inverted planar perovskite solar cells
Sun et al. Nanostructured silicon used for flexible and mobile electricity generation
Johar et al. Facile growth of high aspect ratio c-axis GaN nanowires and their application as flexible pn NiO/GaN piezoelectric nanogenerators
Tanabe et al. Flexible thin-film InAs/GaAs quantum dot solar cells
US9214343B2 (en) ZNSNO3/ZNO nanowire having core-shell structure, method of forming ZNSNO3/ZNO nanowire and nanogenerator including ZNSNO3/ZNO nanowire, and method of forming ZNSNO3 nanowire and nanogenerator including ZNSNO3 nanowire
CN109327160B (en) P-type self-rectifying piezoelectric energy harvester
TW201133974A (en) Method for improving the efficiency of a flexible organic solar cell
Nie et al. Piezo-phototronic effect enhanced photodetectors based on MAPbI 3 perovskite
Liu et al. Recent progress of heterostructures based on two dimensional materials and wide bandgap semiconductors
Zhang et al. Piezo‐Phototronic Matrix via a Nanowire Array
US10256362B2 (en) Flexible silicon infrared emitter
CN109461810B (en) Ultrafast electron transmission piezoelectric energy harvester and preparation method thereof
US20150380582A1 (en) Voltaic Cell
CN107768523B (en) Homogeneous junction perovskite thin film solar cell and preparation method thereof
US8859310B2 (en) Methods of fabricating optoelectronic devices using semiconductor-particle monolayers and devices made thereby
Chang et al. ZnO nanorods array/BaTiO 3 coating layer composite structure nanogenerator
JP2002151708A (en) Photovoltaic element
CN111431433B (en) Direct current generator based on dynamic semiconductor homojunction and preparation method thereof
Alharbi et al. Advanced integrated sensor and layer transfer technologies for wearable bioelectronics
Zhu et al. A perspective on piezotronics and piezo-phototronics based on the third and fourth generation semiconductors

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant