WO2019135911A1

WO2019135911A1 - Piezoelectric materials and devices and methods for preparing the same

Info

Publication number: WO2019135911A1
Application number: PCT/US2018/066409
Authority: WO
Inventors: Richa Pandey; Sankesha BHOYAR; Ankur Kadam; Dinesh Kabra; Ramgopal Rao; Suresh CHAND SETH
Original assignee: Applied Materials, Inc.
Priority date: 2018-01-08
Filing date: 2018-12-19
Publication date: 2019-07-11

Abstract

Piezoelectric devices and methods for forming the piezoelectric devices are provided. The piezoelectric device includes a piezoelectric film disposed on a substrate, where the piezoelectric film contains formamidinium tin iodide and one or more polymeric materials. The piezoelectric device also includes one or more electrodes coupled to, disposed on, or at least in contact with the piezoelectric film. In some embodiments, the piezoelectric film contains a piezoelectric composite material which contains the formamidinium tin iodide and the polymeric material uniformly distributed throughout the piezoelectric composite material. In other embodiments, the piezoelectric film contains a piezoelectric film stack which contains a first layer containing the formamidinium tin iodide and a second layer containing the polymeric material.

Description

PIEZOELECTRIC MATERIALS AND DEVICES AND

METHODS FOR PREPARING THE SAME

BACKGROUND

Field

[0001] Embodiments described herein generally relate to piezoelectric devices, and more specifically, piezoelectric materials and devices and methods for preparing piezoelectric materials and devices.

Description of the Related Art

[0002] Energy harvesting techniques have attracted significant interest in recent years for the ability to derive energy from various types of kinetic energy, such as solar power or wind energy. Several innovations are focused on reducing the cost of implementation of kinetic energy, increasing the efficiency of electrical components, refining the material usage, improve the durability, and increase the throughputs of materials used. In this regard, piezoelectric nano-generators have generated tremendous interest as they are capable of generating electric power locally through stress or flexing, especially in integrated circuits. Piezoelectric ceramics, for instance, are used as a material for filters, thin film dielectric layers, actuators, transducers, or any other device capable of converting an electrical energy directly into a mechanical energy. At present, a perovskite compound containing lead, such as lead zirconate titanate (Pb(ZrTi)0₃, or PZT), is the most commonly used piezoelectric material.

[0003] However, forming a high density lead-based piezoelectric material is difficult to manufacture. Different phases of piezoelectric ceramics and crystals exhibit vastly different electrical, mechanical, piezoelectric, pyroelectric, and optical properties. The structure of these materials is dependent not only on chemical composition but also on temperature. Achieving good piezoelectric properties in such lead-based materials requires a hot pressing process which is expensive, inefficient, and restricts the design of the configuration and the size of the structure. Additionally, lead based piezoelectric materials are expensive to dispose of because of the high environmental harm caused by the lead.

[0004] Therefore, there remains a need for a new piezoelectric materials and devices and methods for preparing piezoelectric materials and devices, especially for lead-free piezoelectric materials and devices.

SUMMARY

[0005] Embodiments of the present disclosure generally relate to piezoelectric devices and methods for forming the piezoelectric devices. In one or more embodiments, the piezoelectric device includes a lead-free, piezoelectric film disposed on a substrate, where the piezoelectric film contains formamidinium tin iodide and one or more polymeric materials. The piezoelectric device also includes one or more electrodes coupled to, disposed on, or at least in contact with the piezoelectric film. In some embodiments, the piezoelectric film contains a piezoelectric composite material which contains the formamidinium tin iodide and the polymeric material uniformly distributed throughout the piezoelectric composite material. In other embodiments, the piezoelectric film contains a piezoelectric film stack which contains a first layer containing the formamidinium tin iodide and a second layer containing the polymeric material.

[0006] In one or more embodiments, a method of forming a piezoelectric device includes combining formamidinium tin iodide, a polymeric material, and a solvent to produce a mixture, coating the mixture on a substrate, and treating the mixture to produce a piezoelectric film comprising the formamidinium tin iodide and the polymeric material disposed on the substrate. The mixture can be treated to produce the piezoelectric film by performing a spin-coating process, a thermal evaporation process, or a combination thereof.

[0007] In other embodiments, a method of forming a piezoelectric device includes depositing a first layer containing a polymeric material on a substrate, depositing a second layer containing formamidinium tin iodide on the first layer to produce a piezoelectric film containing the formamidinium tin iodide and the polymeric material, and depositing an electrode on the piezoelectric film.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0009] Figure 1 is a cross-sectional view of a piezoelectric device, as described and discussed in one or more embodiments herein.

[0010] Figure 2 is a cross-sectional view of another piezoelectric device, as described and discussed in one or more embodiments herein.

[0001] Figure 3 is a cross-sectional view of a processing chamber that may be used to deposit a dielectric layer, as described and discussed in one or more embodiments herein.

[0011] Figure 4 is a schematic illustration of a piezoelectric film stack, as described and discussed in one or more embodiments herein

[0012] Figure 5 is a flow diagram of a method for manufacturing a piezoelectric material on a substrate, as described and discussed in one or more embodiments herein.

[0013] Figure 6 is a flow diagram of a method for manufacturing a piezoelectric material on a substrate, as described and discussed in one or more embodiments herein. [0014] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

[0015] Embodiments of the present disclosure generally relate to piezoelectric devices and methods for forming the piezoelectric devices. Figure 1 is a cross- sectional view of a piezoelectric device 100, as described and discussed in one or more embodiments herein. The piezoelectric device 100 includes a lead-free, piezoelectric film 1 10 disposed on a substrate 102. The piezoelectric film 1 10 contains formamidinium tin iodide (FASnl₃) and one or more polymeric materials. The piezoelectric device 100 also includes one, two, or more electrodes 104, 106 coupled to, disposed on, or at least in contact with the piezoelectric film. As depicted, the electrode 104 is disposed between the substrate 100 and the piezoelectric film 1 10. The electrode 106 is disposed on the opposite side of the piezoelectric film 1 10 as the electrode 104.

[0016] The term "lead-free" - in use with piezoelectric materials and devices - means piezoelectric materials and devices which do not contain lead or a significant amount of lead. Although lead zirconate titanate and other lead compounds have been used in piezoelectric devices, the piezoelectric materials and devices described and discussed herein contain lead-free compounds or perovskite compounds, such as, for example, formamidinium tin iodide.

[0017] In one or more embodiments, the piezoelectric film 1 10 contains a piezoelectric composite material. The piezoelectric composite material contains the formamidinium tin iodide and the polymeric material completely or substantially uniformly distributed throughout the piezoelectric composite material within the piezoelectric film 1 10. [0018] The piezoelectric composite material within the piezoelectric film 1 10 contains about 10 wt%, about 20 wt%, about 30 wt%, or about 50 wt% to about 60 wt%, about 70 wt%, about 80 wt%, or about 90 wt% of the formamidinium tin iodide. For example, the piezoelectric composite material within the piezoelectric film 1 10 contains about 10 wt% to about 90 wt%, about 10 wt% to about 70 wt%, about 10 wt% to about 50 wt%, about 10 wt% to about 30 wt%, about 20 wt% to about 90 wt%, about 20 wt% to about 70 wt%, about 20 wt% to about 50 wt%, about 20 wt% to about 30 wt%, about 40 wt% to about 90 wt%, about 40 wt% to about 70 wt%, or about 40 wt% to about 50 wt% of the formamidinium tin iodide.

[0019] The piezoelectric composite material within the piezoelectric film 1 10 contains about 10 wt%, about 20 wt%, about 30 wt%, or about 50 wt% to about 60 wt%, about 70 wt%, about 80 wt%, or about 90 wt% of the polymeric material. For example, the piezoelectric composite material within the piezoelectric film 1 10 contains about 10 wt% to about 90 wt%, about 10 wt% to about 70 wt%, about 10 wt% to about 50 wt%, about 10 wt% to about 30 wt%, about 20 wt% to about 90 wt%, about 20 wt% to about 70 wt%, about 20 wt% to about 50 wt%, about 20 wt% to about 30 wt%, about 40 wt% to about 90 wt%, about 40 wt% to about 70 wt%, or about 40 wt% to about 50 wt% of the polymeric material.

[0020] In one or more examples, the piezoelectric composite material within the piezoelectric film 1 10 contains about 10 wt% to about 30 wt% of the formamidinium tin iodide and about 70 wt% to about 90 wt% of the polymeric material. In some examples, the piezoelectric composite material within the piezoelectric film 1 10 contains about 40 wt% to about 60 wt% of the formamidinium tin iodide and about 40 wt% to about 60 wt% of the polymeric material. In other examples, the piezoelectric composite material within the piezoelectric film 1 10 contains about 70 wt% to about 90 wt% of the formamidinium tin iodide and about 10 wt% to about 30 wt% of the polymeric material.

[0021] In one or more embodiments, a method of forming a piezoelectric device, such as, for example, the piezoelectric device 100, includes combining formamidinium tin iodide, one or more polymeric materials, and one or more solvents to produce a mixture, coating the mixture on a substrate, an electrode, or other layer or surface, and treating the mixture to produce a piezoelectric film containing the formamidinium tin iodide and the polymeric material disposed on the substrate. The mixture can be treated to produce the piezoelectric film by performing a spin-coating process, a thermal evaporation process, or a combination thereof. Exemplary solvents can be or include dimethylformamide (DMF), tetrahydrofuran (THF), pyridine, acetonitrile, or any mixture thereof.

[0022] In one or more examples, the mixture containing the formamidinium tin iodide, the polymeric material, and the solvent can be produced from combining a formamidinium tin iodide stock solution and a polymeric material stock solution. The formamidinium tin iodide stock solution can be produced by combining tin iodide, formamidinium iodide, and one or more solvents, such as DMF. The polymeric material stock solution can be produced by combining one or more polymeric materials and one or more solvents, such as DMF. The formamidinium tin iodide stock solution and the polymeric material stock solution are combined to form a solution mixture that is spin-coated or thermally evaporated to produce the piezoelectric composite material. In one or more examples, the solution mixture is heated to a temperature of about 60°C to about 80°C for about 10 hours to about 15 hours to form a free-standing piezoelectric film of the piezoelectric composite material. Two electrodes, such as a metallic film, foil, or tape, can be adhered or otherwise attached to both sides of the piezoelectric film, one electrode on each side of the piezoelectric film.

[0023] Figure 2 is a cross-sectional view of another piezoelectric device 200, as described and discussed in one or more embodiments herein. The piezoelectric device 200 includes a lead-free, piezoelectric film 210 disposed on a substrate 102. The piezoelectric film 210 contains formamidinium tin iodide and one or more polymeric materials. The piezoelectric device 200 also includes one, two, or more electrodes 104, 106 coupled to, disposed on, or at least in contact with the piezoelectric film. As depicted, the electrode 104 is disposed between the substrate 100 and the piezoelectric film 210. The electrode 106 is disposed on the opposite side of the piezoelectric film 210 as the electrode 104.

[0024] In one or more embodiments, the piezoelectric film 210 is or contains a piezoelectric film stack which contains one or more first layers 212 and one or more second layers 214. In some examples, the first layer 212 contains the formamidinium tin iodide and the second layer 214 contains the polymeric material. In other examples, the first layer 212 contains the polymeric material and the second layer 214 contains the formamidinium tin iodide. Figure 2 illustrates the piezoelectric film 210 containing four pairs of the first layers 212 and the second layers 214 sequentially stacked on one another. However, the piezoelectric film stack within the piezoelectric film 210 can include one pair of the first layers 212 and the second layers 214 or can include a plurality of the first layers 212 and the second layers 214 sequentially stacked together. The piezoelectric film stack within the piezoelectric film 210 can include from 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, about 15, or about 20 to about 25, about 30, about 50, about 70, about 80, about 90, about 100, or about 120 pairs of the first layers 212 and the second layers 214. For example, the piezoelectric film stack within the piezoelectric film 210 can include from 1 to about 120, from 2 to about 120, from 3 to about 120, from 4 to about 120, from 5 to about 120, from 10 to about 120, from about 25 to about 120, from about 50 to about 120, from about 70 to about 120, from about 90 to about 120, from 1 to about 100, from 2 to about 100, from 3 to about 100, from 4 to about 100, from 5 to about 100, from 10 to about 100, from about 25 to about 100, from about 50 to about 100, from about 70 to about 100, from about 90 to about 100, from 1 to about 80, from 2 to about 80, from 3 to about 80, from 4 to about 80, from 5 to about 80, from 10 to about 80, from about 25 to about 80, from about 50 to about 80, or from about 70 to about 80 pairs of the first layers 212 and the second layers 214. Also, although Figure 2 illustrates the piezoelectric film 210 having the first layer 212 disposed on the electrode 104 and the electrode 106 disposed on the second layer 214, other configurations or arrangements can also be used. For example, although not shown, the piezoelectric film 210 can have the second layer 214 disposed on the electrode 104 and the electrode 106 disposed on the first layer 212.

[0025] In one or more embodiments, a method of forming a piezoelectric device, such as, for example, the piezoelectric device 200, includes depositing a first layer containing a polymeric material on a substrate, depositing a second layer containing formamidinium tin iodide on the first layer to produce a piezoelectric film containing the formamidinium tin iodide and the polymeric material. In some examples, the first and second layers are sequentially deposited such that the piezoelectric film stack contains a plurality of the first layers and the second layers sequentially stacked together. One, two, or more electrodes are deposited, formed, or otherwise attached to the piezoelectric film. The electrodes, such as a metallic film, foil, or tape, can be adhered or otherwise attached to both sides of the piezoelectric film, one electrode on each side of the piezoelectric film.

[0026] The layer containing the polymeric material is deposited, produced, or otherwise formed by a spin-coating process, a thermal evaporation process, or a combination thereof. The polymeric material stock solution, as described and discussed above, can be used during the spin-coating process or the thermal evaporation process to produce the layer containing the polymeric material. The layer containing the formamidinium tin iodide is deposited, produced, or otherwise formed by a spin-coating process, a thermal evaporation process, a vapor deposition process, or any combination thereof. The formamidinium tin iodide stock solution, as described and discussed above, can be used during the spin-coating process or the thermal evaporation process to produce the layer containing the formamidinium tin iodide. During a vapor deposition process, tin iodide and formamidinium iodide can be vaporized and simultaneously or sequentially exposed to the surface to be deposited on. Exemplary vapor deposition processes can be or include chemical vapor deposition (CVD), pulsed-CVD, plasma enhanced CVD (PE-CVD), atomic layer deposition (ALD), plasma enhanced ALD (PE-ALD), physical vapor deposition (PVD), pulsed laser deposition (PLD), or any combination thereof. [0027] In one or more examples, one or more layers 212 containing the polymeric material are formed by spin coating and one or more layers 214 containing the formamidinium tin iodide are formed by thermal evaporation. In some examples, one or more layers 212 containing the polymeric material are formed by spin coating and one or more layers 214 containing the formamidinium tin iodide are formed by spin coating. In other examples, one or more layers 212 containing the polymeric material are formed by thermal evaporation and one or more layers 214 containing the formamidinium tin iodide are formed by thermal evaporation. In some examples, one or more layers 212 containing the polymeric material are formed by spin coating and one or more layers 214 containing the formamidinium tin iodide are formed by vapor deposition. In other examples, one or more layers 212 containing the polymeric material are formed by thermal evaporation and one or more layers 214 containing the formamidinium tin iodide are formed by vapor deposition.

[0028] The substrate 102 can contain glass or a polymer such as polyethylene terephthalate (PET). For example, the substrate 102 can be a glass substrate or a PET substrate. Each of the electrodes 104, 106 can independently be a primary electrode or a secondary electrode. Each of the electrodes 104, 106 can independently include one or more types of materials, such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), chromium, gold, a chromium gold alloy, silver, copper, titanium, platinum, palladium, iridium, alloys thereof, or any combination thereof. In one or more examples, the substrate 102 includes one or more electrodes 104 disposed on the upper surface of the substrate 102. Each of the electrodes can independently be or include one or more conductive films, layers, coatings, foils, sheets, tape, or any combination thereof which are formed, deposited, plated, disposed, or otherwise placed on or in contact with the substrate 102 and/or the piezoelectric films 1 10, 210. Exemplary substrate-electrode combinations can be or include ITO coated glass, FTO coated glass, metal coated glass, ITO coated PET sheet, FTO coated PET sheet, metal coated PET sheet, silicon, metal coated silicon, or a combination thereof. In some examples, a chromium gold alloy coated glass or PET sheet. [0029] The polymer material contained in the piezoelectric films 1 10, 210 can independently be or include one or more of polyvinylidene difluoride (PVDF), polyethylene oxide) (PEO), polydimethylsiloxane (PDMS), poly(vinylidenefluoride-co- trifluoroethylene) (PVDF-TrFE), poly(methyl methacrylate) (PMMA), polystyrene (PS), poly(3,4-ethylenedioxythiophese) (PEDOT), poly(3,4-ethylenedioxythiophese) polystyrene sulfonate (PEDOT: PSS), copolymers thereof, derivatives thereof, or any combination thereof.

[0030] In one or more embodiments, each of the piezoelectric films 1 10, 210 can have a thickness of about 0.5 pm, about 1 pm, about 20 pm, about 50 pm, about 100 pm, about 150 pm, about 200 pm, about 300 pm, or about 500 pm to about 700 pm, about 850 pm, about 1 mm, about 1.5 mm, about 2 mm, about 2.5 mm, about 3 mm, about 4 mm, or about 5 mm. In some examples, each of the piezoelectric films 1 10, 210 can have a thickness of about 0.5 pm to about 500 pm, about 0.5 pm to about 350 pm, about 0.5 pm to about 300 pm, about 0.5 pm to about 250 pm, about 0.5 pm to about 200 pm, about 0.5 pm to about 150 pm, about 0.5 pm to about 100 pm, about 0.5 pm to about 50 pm, about 0.5 pm to about 10 pm, about 10 pm to about 500 pm, about 10 pm to about 350 pm, about 10 pm to about 300 pm, about 10 pm to about 250 pm, about 10 pm to about 200 pm, about 10 pm to about 150 pm, about 10 pm to about 100 pm, about 10 pm to about 50 pm, about 100 pm to about 500 pm, about 100 pm to about 350 pm, about 100 pm to about 300 pm, about 100 pm to about 250 pm, about 100 pm to about 200 pm, or about 100 pm to about 150 pm. In other examples, each of the piezoelectric films 1 10, 210 can have a thickness of about 500 pm to about 5 mm, about 700 pm to about 5 mm, about 850 pm to about 5 mm, about 1 mm to about 5 mm, about 1.5 mm to about 5 mm, about 2 mm to about 5 mm, about 3 mm to about 5 mm, about 4 mm to about 5 mm, about 500 pm to about 3 mm, about 700 pm to about 3 mm, about 850 pm to about 3 mm, about 1 mm to about 3 mm, about 1 .5 mm to about 3 mm, about 2 mm to about 3 mm, about 500 pm to about 1.5 mm, about 700 pm to about 1.5 mm, about 850 pm to about 1.5 mm, or about 1 mm to about 1.5 mm. [0031] A force is applied across the piezoelectric devices 100 and 200 in order to generate power from the piezoelectric film. The force applied across the piezoelectric devices 100 and 200 in order to generate power can be about 30 N, about 40 N, about 50 N, about 60 N, about 80 N, or about 100 N to about 120 N, about 150 N to about 200 N, about 250 N, about 300 N, about 400 N, or about 500 N. For example, the force applied across the piezoelectric devices 100 and 200 in order to generate power can be about 30 N to about 500 N, about 40 N to about 400 N, about 40 N to about 300 N, about 40 N to about 200 N, about 40 N to about 150 N, about 40 N to about 100 N, about 40 N to about 80 N, about 80 N to about 400 N, about 80 N to about 300 N, about 80 N to about 200 N, about 80 N to about 150 N, or about 80 N to about 100 N.

[0032] In one or more embodiments, each of the piezoelectric devices 100 and 200 can independently generate about 10 volts, about 15 volts, about 20 volts, about 30 volts, about 40 volts, or about 50 volts to about 60 volts, about 80 volts, about 100 volts, about 150 volts, about 200 volts, about 250 volts, about 300 volts, about 400 volts, or more. For example, each of the piezoelectric devices 100 and 200 can independently generate about 10 volts to about 400 volts, about 10 volts to about 300 volts, about 10 volts to about 250 volts, about 10 volts to about 200 volts, about 10 volts to about 150 volts, about 10 volts to about 100 volts, about 10 volts to about 80 volts, about 10 volts to about 50 volts, about 20 volts to about 400 volts, about 20 volts to about 300 volts, about 20 volts to about 250 volts, about 20 volts to about 200 volts, about 20 volts to about 150 volts, about 20 volts to about 100 volts, about 20 volts to about 80 volts, about 20 volts to about 50 volts, about 50 volts to about 400 volts, about 50 volts to about 300 volts, about 50 volts to about 250 volts, about 50 volts to about 200 volts, about 50 volts to about 150 volts, about 50 volts to about 100 volts, or about 50 volts to about 80 volts.

[0033] In some embodiments, each of the piezoelectric devices 100 and 200 can independently have a piezoelectric modulus or coefficient (d₃₃) of about 30 pm/V, about 35 pm/V, about 40 pm/V, or about 50 pm/V to about 55 pm/V, about 60 pm/V, about 80 pm/V, about 90 pm/V, or about 100 pm/V. For example, each of the piezoelectric devices 100 and 200 can independently have a piezoelectric modulus or coefficient (d₃₃) of about 30 pm/V to about 100 pm/V, about 40 pm/V to about 100 pm/V, about 50 pm/V to about 100 pm/V, about 60 pm/V to about 100 pm/V, about 80 pm/V to about 100 pm/V, about 30 pm/V to about 90 pm/V, about 40 pm/V to about 90 pm/V, about 50 pm/V to about 90 pm/V, about 60 pm/V to about 90 pm/V, about 80 pm/V to about 90 pm/V, about 30 pm/V to about 80 pm/V, about 40 pm/V to about 80 pm/V, about 50 pm/V to about 80 pm/V, about 60 pm/V to about 80 pm/V, or about 80 pm/V to about 80 pm/V.

[0034] In one or more embodiments, each of the piezoelectric devices 100 and 200 can independently have a power density of about 10 mWcm ², about 50 mWcm ², about 100 mWcm ², about 150 mWcm ², about 200 mWcm ², or about 300 mWcm ² to about 400 mWcm ², about 500 mWcm ², about 700 mWcm ², about 850 mWcm ², about 1 Worn ², about 1.2 Worn ², about 1.5 Worn ², about 1.8 Worn ², about 2 Worn ², about 2.5 Worn ², or about 3 Worn ². For example, each of the piezoelectric devices 100 and 200 can independently have a power density of about 10 mWcm ² to about 3 Worn ², about 10 mWcm ² to about 2 Worn ², about 10 mWcm ² to about 1.5 Worn ², about 10 mWcm ² to about 1 Worn ², about 10 mWcm ² to about 700 mWcm ², about 10 mWcm ² to about 500 mWcm ², about 10 mWcm ² to about 300 mWcm ², about 10 mWcm ² to about 100 mWcm ², or about 10 mWcm ² to about 50 mWcm ².

[0035] Figure 3 is a schematic cross-section view of one embodiment of a chemical vapor deposition (CVD) processing chamber 300 in which a lead-free piezoelectric layer, such as a FASnl₃ layer, may be deposited. One suitable CVD processing chamber, such as plasma enhanced CVD (PECVD) processing chamber, is available from Applied Materials, Inc., located in Santa Clara, CA. It is contemplated that other deposition chambers, such as atomic layer deposition (ALD), plasma vapor deposition (PVD), pulsed laser deposition (PLD), or thermal evaporation chambers, including those from Applied Materials, Inc., as well as from other manufacturers, may be utilized to practice the present disclosure. [0036] The processing chamber 300 generally includes one or more walls 342, a bottom 304 and a lid 312 which bound a process volume 306. A gas distribution plate 310 and substrate support assembly 330 are disposed within the process volume 306. The process volume 306 is accessed through a slit valve opening 308 formed through the wall 342 such that a substrate 102 may be transferred into and out of the chamber 300.

[0037] The substrate support assembly 330 includes a substrate receiving surface

332 for supporting the substrate 102. A stem 334 couples the substrate support assembly 330 to a lift system 336 which raises and lowers the substrate support assembly 330 between substrate transfer and processing positions. A shadow frame

333 may be optionally placed over periphery of the substrate 102 during processing to prevent deposition on the edge of the substrate 102. Lift pins 338 are moveably disposed through the substrate support assembly 330 and are adapted to space the substrate 102 from the substrate receiving surface 332. The substrate support assembly 330 may also include heating and/or cooling elements 339 utilized to maintain the substrate support assembly 330 at a predetermined temperature. The substrate support assembly 330 may also include grounding straps 331 to provide an RF return path around the periphery of the substrate support assembly 330.

[0038] The gas distribution plate 310 is coupled at its periphery to the lid 312 or wall 342 of the processing chamber 300 by a suspension 314. The gas distribution plate 310 is also coupled to the lid 312 by one or more center supports 316 to help prevent sag and/or to control the straightness/curvature of the gas distribution plate 310. It is contemplated that the one or more center supports 316 may not be utilized. The gas distribution plate 310 may have different configurations with different dimensions. The gas distribution plate 310 has a downstream surface 350 having a plurality of apertures 31 1 formed therein facing an upper surface 318 of the substrate 102 disposed on the substrate support assembly 330. The apertures 31 1 may have different shapes, number, densities, dimensions, and distributions across the gas distribution plate 310. In one embodiment, a diameter of the apertures 31 1 may be selected between about 0.01 inch and about 1 inch. [0039] A gas source 320 is coupled to the lid 312 to provide gas through the lid 312 and then through the apertures 31 1 formed in the gas distribution plate 310 to the process volume 306. A vacuum pump 309 is coupled to the processing chamber 300 to maintain the gas in the process volume 306 at a predetermined pressure.

[0040] An RF power source 322 is coupled to the lid 312 and/or to the gas distribution plate 310 to provide a RF power that creates an electric field between the gas distribution plate 310 and the substrate support assembly 330 so that a plasma may be generated from the gases present between the gas distribution plate 310 and the substrate support assembly 330. The RF power may be applied at various RF frequencies. For example, RF power may be applied at a frequency between about 0.3 MHz and about 200 MHz. In one embodiment the RF power is provided at a frequency of 13.56 MHz.

[0041] A remote plasma source 324, such as an inductively coupled remote plasma source, may also be coupled between the gas source 320 and the gas distribution plate 310. Between processing substrates, a cleaning gas may be energized in the remote plasma source 324 to remotely provide plasma utilized to clean chamber components. The cleaning gas entering the process volume 306 may be further excited by the RF power provided to the gas distribution plate 310 by the power source 322. Suitable cleaning gases include, but are not limited to, NF₃, F₂, and SF₆.

[0042] In one embodiment, the substrate 102 that may be processed in the processing chamber 300 may have a surface area of 10,000 cm² or more, such as 25,000 cm² or more, for example about 55,000 cm² or more. The substrate 102 may be made from a material selected from indium tin oxide coated glass (hard as well as flexible glass substrate), fluoride coated tin oxide (hard as well as flexible glass substrate), silicon, metal coated silicon, indium tin oxide coated polyethylene terephthalate (PET) sheet, metal coated PET sheet, or any combination thereof. It is understood that after processing the substrate may be cut to form smaller other devices. [0043] In one or more embodiments, the heating and/or cooling elements 339 may be set to provide a substrate support assembly temperature during deposition of about 600°C or less, for example, in a range from about 50°C to about 500°C, from about 70°C to about 220°C, or from about 160°C to about 200°C.

[0044] Figure 4 is a schematic illustration of a piezoelectric film stack 400. The piezoelectric film stack 400 includes a substrate 102, an intermediate layer 410, and a piezoelectric layer 420. In one implementation, the intermediate layer 410 is between the substrate 102 and the piezoelectric layer 420. In one implementation, the intermediate layer 410 is a poly(3,4-ethylenedioxythiophese) polystyrene sulfonate (PEDOT:PSS) layer.

[0045] In one implementation, the piezoelectric layer 420 is a lead-free piezoelectric material and a perovskite compound (ABX₃), where A can be or include formamidinium (FA), methylammonium (MA), guanidinium, barium, cesium, or any combination thereof; B can be or include tin (Sn⁺²), titanium (Ti²⁺), barium (Ba⁺²), or any combination thereof; and X can be or include iodide (G), bromide (Br ), chloride (Cl ), oxide (O² ), or any combination thereof. The piezoelectric material can be or include formamidinium tin iodide (FASnl₃), barium titanate (BaTi0₃), aluminum nitride (AIN), potassium sodium niobate (KNN) (K_xNai_-xNb0₃, where x is greater than 0 and less than 1 ), ceramics thereof, derivatives thereof, or any combination thereof. In one implementation, the lead-free piezoelectric material exhibits photo-ferroic effects.

[0046] The lead-free piezoelectric layer 420 exhibits a piezoelectric modulus or coefficient (d₃₃) in a range from about 51 pm/V to about 61 pm/V. In one implementation, the lead-free piezoelectric layer 420 has a diffusion length of greater than 100 pm, a tunable bandgap in a range from about 1.45 eV to about 2.4 eV, and an absorption coefficient of greater than 105 cm ¹. In one implementation, the piezoelectric material includes an organic polymer such as polyethylene glycol and polymethylmethacrylate to improve the piezoresponse and nanogenerator device efficiency. It has been observed that the addition of SnF₂ (tin fluoride) in the system slows the rate of oxidation of Sn(ll) to Sn(IV), which also reduces the conductivity of the tin based perovskite system and helps in achieving more stability of FASnl₃ system.

[0047] Figure 5 is a flow diagram of a method 500 for manufacturing a piezoelectric material on a substrate 102, according to embodiments described herein. At block 502, an intermediate layer 410 is deposited on the substrate 102. In one implementation, the substrate 102 is treated with oxygen plasma for between 10 min to 20 min. In one implementation, the intermediate layer 410 is heated to a temperature in a range from about 70°C to about 200°C for a period of time in a range from about 30 min to about 2 hours. In one implementation, a nitrogen gas is provided during the intermediate layer 410 deposition. The substrate 102 is placed in a chamber, such as the processing chamber 300 (Figure 3). At block 504, a first precursor gas is provided to the processing chamber 300. The first precursor gas is or contains formamidinium iodide. At block 506, a second precursor gas is provided to the processing chamber 300. The second precursor gas is or contains tin iodide gas. At block 508, a nitrogen gas is provided to the processing chamber 300. At block 510, a piezoelectric material is deposited on the substrate 102 forming a lead- free piezoelectric layer 420. In one implementation, the lead-free piezoelectric layer 420 is annealed. In one implementation, the deposition of the lead-free piezoelectric layer 420 occurs at a temperature less than 250°C. In one implementation, the temperature of the chamber 300 is in a range from about 100°C to about 220°C. In another implementation, the temperature of the processing chamber 300 is in a range from about 150°C to about 210°C. In yet another implementation, the temperature of the processing chamber 300 is in a range from about 70°C to about 200°C. In one implementation, a tin fluoride (SnF₂) gas is provided to the processing chamber 300 during the formation of the lead-free piezoelectric material. In another implementation, an additive for restricting the grain growth is added to the processing chamber 300 during the formation of the lead-free piezoelectric material.

[0048] Figure 6 flow diagram of a method 600 for manufacturing a piezoelectric material on a substrate 102, according to embodiments described herein. At block 602, an intermediate layer 410 is deposited on the substrate 102. In one implementation, the substrate 102 is treated with oxygen plasma for between 10 min to 20 min prior to depositing the intermediate layer 410. In one implementation, the intermediate layer 410 is heated to a temperature in a range from about 70°C to about 200°C for a period of time in a range from about 30 min to about 2 hours. In one implementation, a nitrogen gas is provided during the intermediate layer 410 deposition. The substrate 102 is placed in a processing chamber, such as a spin- coating chamber. At block 604, a perovskite precursor solution is deposited onto the intermediate layer 410 to form a lead-free piezoelectric layer 420. In one implementation, the perovskite precursor solution contains about 2:1 tin iodide to formamidinium iodide. In one implementation, dimethylformamide (DMF) is added to the perovskite precursor solution. In one implementation, a tin fluoride (SnF₂) solution is added to the perovskite precursor solution. In one implementation, the perovskite precursor solution is spun at a rate in a range from about 1 ,500 rpm to about 5,500 rpm for about 45 seconds to about 75 seconds. At block 606, the substrate 102, the intermediate layer 410, and the lead-free piezoelectric layer 420 is annealed. In one implementation, the anneal is performed at a temperature in a range from about 65°C to about 75°C for a period of time from about 30 minutes to about 2 hours.

[0049] By manufacturing the lead-free formamidinium tin iodide layer as described above, a FASnl₃ layer or film, with a piezoelectric modulus or coefficient (d₃₃) of about 50 pm/V to about 80 pm/V, is formed that advantageously exhibits photo- ferroic properties with a high degree of efficiency that can be utilized as a piezoelectric film or device. In some examples, without undergoing any external poling treatment, the fabricated piezoelectric devices show output voltages of up to about 23 V and power density of about 13 mWcrm ² under a periodic vertical compression, with a release pressure of about 0.1 MPa. The lead-free formamidinium tin iodide layer is an inorganic-organic hybrid perovskite composition that does not pollute the environment, acts as a piezoelectric and photovoltaic material, is cost efficient to manufacture, exhibit a high blocking force, require a low power consumption when integrated into semiconductor devices, and has a relatively wide frequency range of operation.

Experimental Section

[0050] Formamidinium iodide, tin iodide, anhydrous dimethylformamide (99.8% purity) and poly(vinyldiene fluoride) average Mw is about 180,000 were purchased from Sigma Aldrich. All the materials and chemicals were used as received/used without further purification. Poly(3,4-ethylenedioxythiophene):polystyrenesulfonate; PEDOTPSS (Clevios™ 4803) purchased from the Heraeus Group.

[0051] Preparation of FASnU and PVDF stock solution: FASnl₃ stock solution was prepared by dissolving 372 mg of tin iodide (Snl₂), 172 mg of formamidinium iodide (FAI) in 1 ml_ of anhydrous dimethylformamide (DMF). The solution was kept stirring for 4 hrs for complete dissolution of precursor materials at room temperature. Poly(vinylidene fluoride) (PVDF) stock solution was prepared by dissolving 225.3 mg in 1 ml_ anhydrous dimethylformamide (DMF). For preparing different composition of nanocomposite films FASnl₃ and PVDF stock solution was mixed in the volume ratio of 1 :0, 0.2:0.8, 0.5:0.5, 0.8:0.2, 0:1 , respectively. All the solution preparation was done inside the N₂-filled glove box.

[0052] Film Preparation of FASnl : FTO glass was ultrasonically cleaned with soap solution, Dl water, acetone, and 2-propanol (IPA) for 15 minutes, respectively. Right before the deposition of the PEDOTPSS solution, the samples were treated with oxygen plasma for 15 min. A PEDOTPSS solution (Clevios™ 4803) was filtered with 0.2 pm nylon filter and then spin-coated onto the substrate in the air (5,000 rpm, for 30 s), followed by heating to 150°C for 30 min under N₂ atmosphere. The substrate was immediately transferred to the glove-box for perovskite precursor (FASnl₃) solution deposition onto PEDOTPSS film at 5,000 rpm for 60 s. After spin coating, the substrates were annealed at 70°C for 30 minutes.

[0053] Piezoresponse Force Micrscopy (PFM) measurement details: In PFM study, the alternating current (AC) voltage is kept constant at 1.5 V and the applied external electric field from the metal (Pt-lr) coated conductive tip is perpendicular to the FASnl₃:PVDF nanocomposite film. The FASnl₃ and FASnl₃:PVDF films were spin coated on PEDOT:PSS/FTO/Glass and FTO/Glass, respectively, and annealed at 70°C, which resulted in compact and homogeneous films of thickness about 130 pm.

[0054] The polarization switching and local piezoelectric response of FASnl₃ and FASnl₃:PVDF nanocomposite films were studied at room temperature with an Asylum Research MFP-3D atomic force microscope working in contact mode. An ASYLEC- 01 cantilever made of a tetrahedral silicon tip coated with titanium/iridium (5/20) was used to apply a small AC voltage with amplitude of 1.2 V. Measurements were performed by applying two oscillating voltages with frequencies below and above resonance (320 kHz), operating the cantilever in the dual AC resonance tracking mode. FASnl₃ film was prepared by spin coating FASnl₃ precursor solution, respectively on 1 cm x 1 cm PEDOT:PSS/FTO coated glass slide and annealed for 30 minutes at 70°C inside the N₂ filled glove box. Similarly, FASnl₃:PVDF film was prepared by spin coating composite of FASnl₃:PVDF on FTO coated glass and annealed for 30 minutes at 70°C inside the N₂ filled glove box.

[0055] Fabrication of FaSn PVDF Nanoqenerator: The stock solutions of FASnl₃ and PVDF were mixed at different (1 :0, 0.2:0.8, 0.5:0.5, 0.8:0.2, 0: 1 ) volume ratio and the mixed solution was placed on the glass petri dish at 70°C for 12 hours for the curing treatment. After 12 hours, the free standing films were formed and which can be peeled off. Further, the FASnl₃:PVDF nanocomposite films was pasted between two Cr/Au coated PET electrode. Copper wires were attached to the top and bottom of the Cr/Au coated PET electrode using copper tape; these were used to collect the generated charge carriers through the external circuit. To protect the as-fabricated PNG from external physical damage, the whole device was encapsulated with scotch tape.

[0056] Embodiments of the present disclosure relate to piezoelectric devices and methods for forming the piezoelectric devices. The piezoelectric devices include a lead-free, piezoelectric film containing formamidinium tin iodide and one or more polymeric materials. The piezoelectric devices are high performance and can be used as a flexible piezoelectric nanogenerator. The piezoelectric devices exhibit a well-developed ferroelectric characteristic and switchable polarization and have very high piezoelectric modulus or coefficient (d₃₃) values. The piezoelectric devices demonstrated superior device performance as a piezoelectric nanogenerator (with maximum voltage output of about 23 V at pressure of about 0.1 MPa), while also enhancing its mechanical flexibility and environmental stability. The piezoelectric devices and films described and discussed here can be utilized in electric generators, air bag sensors, air flow sensors, audible alarms, fuel atomizers, keyless door entry, seat belt buzzers, knock sensors, disc drives, inkjet printers, cigarette lighters, depth finders, fish finders, humidifiers, jewelry cleaners, musical instruments, speakers, telephones and cellular phones, disposable patient monitors, fetal heart monitors, ultrasonic imaging, depth sounders, guidance systems, hydrophones, sonars, and other devices.

[0057] Embodiments of the present disclosure further relate to any one or more of the following paragraphs:

[0058] 1. A piezoelectric device, comprising: a piezoelectric film disposed on a substrate, wherein the piezoelectric film comprises formamidinium tin iodide and a polymeric material; and an electrode coupled to the piezoelectric film.

[0059] 2. A method of forming a piezoelectric device, comprising: combining formamidinium tin iodide, a polymeric material, and a solvent to produce a mixture; coating the mixture on a substrate; and treating the mixture to produce a piezoelectric film comprising the formamidinium tin iodide and the polymeric material disposed on the substrate.

[0060] 3. The method of paragraph 2, wherein treating the mixture to produce the piezoelectric film comprises performing a spin-coating process, a thermal evaporation process, or a combination thereof. [0061] 4. The method of paragraph 3, wherein the piezoelectric film comprises a piezoelectric composite material comprising the formamidinium tin iodide and the polymeric material uniformly distributed throughout.

[0062] 5. A method of forming a piezoelectric device, comprising: depositing a first layer comprising a polymeric material on a substrate; depositing a second layer comprising formamidinium tin iodide on the first layer to produce a piezoelectric film comprising the formamidinium tin iodide and the polymeric material; and depositing an electrode on the piezoelectric film.

[0063] 6. The method of paragraph 5, further comprising sequentially depositing the first and second layers such that the piezoelectric film stack comprises a plurality of the first layers and the second layers sequentially stacked together.

[0064] 7. The method of paragraph 6, wherein the piezoelectric film stack comprises from 3 pairs of the first layers and the second layers to about 100 pairs of the first layers and the second layers.

[0065] 8. The method of paragraph 5, wherein the first layer comprising the polymeric material is deposited by a spin-coating process, a thermal evaporation process, or a combination thereof, and wherein the second layer comprising the formamidinium tin iodide is deposited by a spin-coating process, a thermal evaporation process, a vapor deposition process, or a combination thereof.

[0066] 9. The method according to any one of paragraphs 2-8, wherein the solvent comprises dimethylformamide (DMF), tetrahydrofuran (THF), pyridine, acetonitrile, or any mixture thereof.

[0067] 10. The piezoelectric device or the method according to any one of paragraphs 1 -9, wherein the piezoelectric film comprises a piezoelectric composite material comprising the formamidinium tin iodide and the polymeric material uniformly distributed throughout. [0068] 1 1. The piezoelectric device or the method according to any one of paragraphs 1 -10, wherein the piezoelectric film comprises a piezoelectric film stack, and wherein the piezoelectric film stack comprises a first layer comprising the formamidinium tin iodide and a second layer comprising the polymeric material.

[0069] 12. The piezoelectric device or the method according to any one of paragraphs 1 -1 1 , wherein the piezoelectric film stack comprises a plurality of the first layers and the second layers sequentially stacked together.

[0070] 13. The piezoelectric device or the method according to any one of paragraphs 1 -12, wherein the piezoelectric film stack comprises from 3 pairs of the first layers and the second layers to about 100 pairs of the first layers and the second layers.

[0071] 14. The piezoelectric device or the method according to any one of paragraphs 1 -13, wherein the polymer material comprises polyvinylidene difluoride (PVDF), polyethylene oxide) (PEO), polydimethylsiloxane (PDMS), poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE), poly(methyl methacrylate) (PMMA), polystyrene (PS), poly(3,4-ethylenedioxythiophese) (PEDOT), poly(3,4- ethylenedioxythiophese) polystyrene sulfonate (PEDOT: PSS), copolymers thereof, derivatives thereof, or any combination thereof.

[0072] 15. The piezoelectric device or the method according to any one of paragraphs 1 -14, wherein the polymer material polyvinylidene difluoride (PVDF).

[0073] 16. The piezoelectric device or the method according to any one of paragraphs 1 -15, wherein the piezoelectric film has a thickness of about 500 nm to about 5 mm.

[0074] 17. The piezoelectric device or the method according to any one of paragraphs 1 -16, wherein the electrode is disposed between the piezoelectric film and the substrate. [0075] 18. The piezoelectric device or the method according to any one of paragraphs 1 -17, wherein the substrate comprises glass or polyethylene terephthalate (PET).

[0076] 19. The piezoelectric device or the method according to any one of paragraphs 1 -18, wherein a secondary electrode is disposed on the piezoelectric film, and wherein the electrode and the secondary electrode are separated by the piezoelectric film.

[0077] 20. The piezoelectric device or the method according to any one of paragraphs 1 -19, wherein the electrode and/or the secondary electrode independently comprises indium tin oxide (ITO), fluorine-doped tin oxide (FTO), chromium, gold, a chromium gold alloy, silver, copper, titanium, platinum, palladium, iridium, alloys thereof, or any combination thereof.

[0078] The terms "over", "under", "between", and "on" as used herein refer to a relative position of one layer with respect to other layers. As such, for example, one layer disposed over or under another layer may be directly in contact with the other layer or may have one or more intervening layers. Moreover, one layer disposed between layers may be directly in contact with the two layers or may have one or more intervening layers. In contrast, a first layer "on" a second layer is in contact with the second layer. Additionally, the relative position of one layer with respect to other layers is provided assuming operations are performed relative to a substrate without consideration of the absolute orientation of the substrate.

[0079] While the foregoing is directed to implementations of the disclosure, other and further implementations may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. All documents described herein are incorporated by reference herein, including any priority documents and/or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of the present disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby. Likewise, the term "comprising" is considered synonymous with the term "including" for purposes of United States law. Likewise whenever a composition, an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition or group of elements with transitional phrases "consisting essentially of," "consisting of", "selected from the group of consisting of," or "is" preceding the recitation of the composition, element, or elements and vice versa.

[0080] Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, and/or the combination of any two upper values are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below.

Claims

Claims:

1. A piezoelectric device, comprising:

a piezoelectric film disposed on a substrate, wherein the piezoelectric film comprises formamidinium tin iodide and a polymeric material; and

an electrode coupled to the piezoelectric film.

2. The piezoelectric device of claim 1 , wherein the piezoelectric film comprises a piezoelectric composite material comprising the formamidinium tin iodide and the polymeric material uniformly distributed throughout.

3. The piezoelectric device of claim 1 , wherein the piezoelectric film comprises a piezoelectric film stack, and wherein the piezoelectric film stack comprises a first layer comprising the formamidinium tin iodide and a second layer comprising the polymeric material.

4. The piezoelectric device of claim 3, wherein the piezoelectric film stack comprises a plurality of the first layers and the second layers sequentially stacked together.

5. The piezoelectric device of claim 4, wherein the piezoelectric film stack comprises from 3 pairs of the first layers and the second layers to about 100 pairs of the first layers and the second layers.

6. The piezoelectric device of claim 1 , wherein the polymer material comprises polyvinylidene difluoride (PVDF), polyethylene oxide) (PEO), polydimethylsiloxane (PDMS), poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE), poly(methyl methacrylate) (PMMA), polystyrene (PS), poly(3,4-ethylenedioxythiophese) (PEDOT), poly(3,4-ethylenedioxythiophese) polystyrene sulfonate (PEDOT:PSS), copolymers thereof, derivatives thereof, or any combination thereof.

7. The piezoelectric device of claim 1 , wherein the electrode is disposed between the piezoelectric film and the substrate, and wherein the substrate comprises glass or polyethylene terephthalate (PET).

8. A method of forming a piezoelectric device, comprising:

combining formamidinium tin iodide, a polymeric material, and a solvent to produce a mixture;

coating the mixture on a substrate; and

treating the mixture to produce a piezoelectric film comprising the formamidinium tin iodide and the polymeric material disposed on the substrate.

9. The method of claim 8, wherein treating the mixture to produce the piezoelectric film comprises performing a spin-coating process, a thermal evaporation process, or a combination thereof.

10. The method of claim 9, wherein the piezoelectric film comprises a piezoelectric composite material comprising the formamidinium tin iodide and the polymeric material uniformly distributed throughout.

1 1. The method of claim 8, wherein the solvent comprises dimethylformamide (DMF), tetrahydrofuran (THF), pyridine, acetonitrile, or any mixture thereof.

12. A method of forming a piezoelectric device, comprising:

depositing a first layer comprising a polymeric material on a substrate;

depositing a second layer comprising formamidinium tin iodide on the first layer to produce a piezoelectric film comprising the formamidinium tin iodide and the polymeric material; and

depositing an electrode on the piezoelectric film.

13. The method of claim 12, further comprising sequentially depositing the first and second layers such that the piezoelectric film stack comprises a plurality of the first layers and the second layers sequentially stacked together.

14. The method of claim 13, wherein the piezoelectric film stack comprises from 3 pairs of the first layers and the second layers to about 100 pairs of the first layers and the second layers.

15. The method of claim 12, wherein the first layer comprising the polymeric material is deposited by a spin-coating process, a thermal evaporation process, or a combination thereof, and wherein the second layer comprising the formamidinium tin iodide is deposited by a spin-coating process, a thermal evaporation process, a vapor deposition process, or a combination thereof.