WO2014193819A1

WO2014193819A1 - A mobile electronic device cover plate comprising graphene

Info

Publication number: WO2014193819A1
Application number: PCT/US2014/039545
Authority: WO
Inventors: Thomas Gutierrez; Parthasarathy Santhanaraghavan
Original assignee: Gtat Corporation
Priority date: 2013-05-28
Filing date: 2014-05-27
Publication date: 2014-12-04

Abstract

An electronic device comprising a cover plate is disclosed in which the cover plate comprises graphene. The cover plate may comprise one or more layers, such as a glass layer, a polymeric material layer, and/or a sapphire layer, and one or more of these layer may comprise graphene.

Description

A MOBILE ELECTRONIC DEVICE COVER PLATE COMPRISING GRAPHENE

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to U.S. Provisional Patent Application Serial Nos.

61/828,012, filed May 28, 2013 and 61/888,654, filed October 9, 2013. The entire contents of these patent applications are hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention.

[0001] The present invention relates to a mobile electronic device comprising a cover plate and, more particularly, a sapphire cover plate.

2. Description of the Related Art.

[0002] There are many types of mobile electronic devices currently available which include a display window assembly that is at least partially transparent. These include, for example, handheld electronic devices such media players, mobile telephones (cell phones), personal data assistants (PDAs), pagers, tablets, and laptop computers and notebooks. The display screen assembly may include multiple component layers, such as, for example, a visual display layer such as a liquid crystal display (LCD), a touch sensitive layer for user input, and at least one outer cover layer used to protect the visual display. Each of these layers are typically laminated or bonded together.

[0003] Many of the mobile electronic devices used today are subjected to excessive mechanical and/or chemical damage, particularly from careless handling and/or dropping, from contact of the screen with items such as keys in a user's pocket or purse, or from frequent touch screen usage. For example, the touch screen surface and interfaces of smartphones and PDAs can become damaged by abrasions that scratch and pit the physical user interface, and these imperfections can act as stress concentration sites making the screen and/or underlying components more susceptible to fracture in the event of mechanical or other shock. Additionally, oil from the use's skin or other debris can coat the surface and may further facilitate the degradation of the device. Such abrasion and chemical action can cause a reduction in the visual clarity of the underlying electronic display components, thus potentially impeding the use and enjoyment of the device and limiting its lifetime.

[0004] Various methods and materials have been used in order to increase the durability of the display windows of mobile electronic devices. For example, polymeric coatings or layers can be applied to the touch screen surface in order to provide a barrier against degradation. However, such layers can interfere with the visual clarity of the underlying electronic display as well as interfere with the touch screen sensitivity. Furthermore, as the coating materials are often also soft, they can themselves become easily damaged, requiring periodic replacement or limiting the lifetime of the device.

[0005] Another common approach is to use more highly chemically and scratch resistant materials as the outer surface of the display window. For example, touch sensitive screens of some mobile devices may include a layer of chemically-strengthened alkali aluminosilicate glass, with potassium ions replacing sodium ions for enhanced hardness, such as the material referred to as Gorilla® glass available from Corning. However, even this type of glass can be scratched by many harder materials, including metal keys, sand, and pebbles, and, further, as a glass, is prone to brittle failure and shattering. Sapphire has also been suggested and used as a material for either the outer layer of the display assembly or as a separate protective sheet to be applied over the display window. However, sapphire is relatively expensive, particularly at the currently available thicknesses.

[0006] Thus, while materials are available which can enable the display of a mobile electronic device to be relatively resistant to damage, there remains a need in the industry for materials and methods for providing improved mechanical toughness and scratch resistance without reducing transmittance. SUMMARY OF THE INVENTION

[0007] The present invention relates to an electronic device comprising a cover plate having at least one transparent display region. The cover plate comprises graphene, such as on one or more surfaces and/or edges. For example, the cover plate can comprise one or more layers, preferably wherein at least one of which comprises graphene. In one embodiment, the cover plate comprises one or more sapphire layers comprising graphene. For example, the sapphire layer can have an exterior-facing surface comprising graphene, an interior-facing surface comprising graphene, or both. The sapphire layer can have a thickness of from about 10 microns to about 500 microns, such from about 10 microns to about 100 microns and from about 25 to about 500 microns. The cover plate may be a single, freestanding layer, such as a sapphire layer, or may comprise more than one layer, such as more than one sapphire layer, each having a thickness of from about 10 microns to about 500 microns. In another embodiment, the cover plate comprises one or more transparent layers, including one or more glass layers and/or one or more polymeric material layers, at least one of which can comprise graphene. The cover plate can be affixed to the surface of a display element of the electronic device, or it may be a protective layer that is removably positioned or placed on top of the display element. The present invention further relates to the cover plate comprising graphene.

[0008] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the present invention, as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG 1 shows a specific embodiment of the cover plate of the electronic device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention relates to an electronic device comprising a cover plate, wherein the cover plate comprises graphene, as well as to the cover plate itself.

[0011] The electronic device of the present invention comprises a cover plate having at least one transparent display region through which an image can be displayed, such as from a display element upon which the cover plate is placed. Non-transparent regions may also be present, particularly as decorative elements such as borders or as elements to delineate various functional sections of the display. The electronic device can be any known in the art comprising a display or display element, such as mobile or portable electronic devices including, but not limited to, electronic media players for music and/or video, such as an mp3 player, mobile telephones (cell phones), personal data assistants (PDAs), pagers, laptop computers, or electronic notebooks or tablets. The display element of the device may include multiple component layers, including, for example, a visual display layer such as an LCD and a touch sensitive layer as part of a touch screen application. The cover plate can be affixed to the display surface of the display element of the device or it can be a separate protective layer that can be placed or positioned over or on top of the display element and later removed if desired.

[0012] The cover plate of the electronic device of the present invention comprises graphene, which is a very light weight carbonaceous material having atoms arranged in a regular hexagonal pattern that has been described as a 2-dimensional single atom layer of graphite. A single layer of graphene is transparent due to its extremely small thickness. Thus, while the cover plate comprises graphene, this material would not be expected to impact the transparency of the cover plate. In addition, due to its network of carbon atoms, graphene is extremely hard yet light weight, which would thereby provide additional mechanical strength to the cover plate, particularly when the cover plate is thin, such as having a thickness of less than 100 microns. Furthermore, due to the electronic structure of graphene, this material is highly conductive and has very low resistivity, which would also be expected to improve the touch sensitivity of the cover plate. Graphene can also be doped using a variety of dopants known in the art in order to modify its properties, including its mechanical and electrical properties.

[0013] The cover plate may comprise graphene in several different ways. For example, the cover plate can have at least one surface comprising graphene, such as a graphene coating. The surface can be an exterior-facing surface (i.e., facing toward the front exterior of the electronic device, in the direction of the device user), an interior-facing surface (i.e., facing inward and away from the front exterior of the electronic device), or one or more edge surfaces (which is more practical the thicker the cover plate is). Combinations of surfaces and edges may also comprise graphene.

[0014] In addition, the cover plate may comprise one or more layers, and at least one or a plurality of these layers, may comprise graphene, such as on an interior-facing surface of any of the layers, an exterior-facing surface of any of the layers, one or more edge surfaces of any of the layers, or combinations thereof. The layers can be, for example, a sapphire layer, a glass layer, or a polymeric material layer. Preferably, the cover plate comprise at least one layer of sapphire.

[0015] Thus, in one embodiment, the cover plate of the electronic device of the present invention comprises one or more sapphire layers or laminae having graphene. The thickness of at least one of the sapphire layers is preferably from about 10 microns to about 500 microns. For example, the sapphire layer can have a thickness of from about 25 microns to about 500 microns, including, from about 50 microns to about 400 microns, from about 50 microns to about 300 microns, from about 50 microns to about 250 microns, from about 50 microns to about 200 microns, from about 50 microns to about 150 microns, and from about 50 microns to about 100 microns. Also, the sapphire layer can have a thickness of from about 10 microns to about 100 microns, such as from about 25 microns to about 100 microns. In particular, the sapphire layer can be an ultrathin sapphire layer having a thickness of less than 100 microns, including less than 50 microns, less than 30 microns, less than 25 microns, and less than 15 microns.

[0016] The cover plate may be a single, free-standing sapphire layer or may comprise multiple layers, at least one of which has a thickness of from about 10 microns to about 500 microns. The cover plate may also comprise more than one sapphire layer or lamina having a thickness of from about 10 microns to about 500 microns, including 2-10 layers, such as 2-5 layers. For example, the cover plate may be a single, free-standing sapphire multilayer composite, wherein in each layer has a thickness of from about 10 microns to about 500 microns. Preferably, the sapphire layer is the exterior layer of the cover plate and the electronic device. The overall thickness of the cover plate of the electronic device of the present invention can vary depending on a variety of factors, including, for example, the number of layers, the desired size of the transparent display region, and the size of the device. In general, the cover plate has a thickness that is less than about 5 mm, such as less than about 3 mm, for a multilayer cover plate.

[0017] Sapphire having a thickness of from about 10 microns to about 500 microns is desirable from a cost point of view. For example, sapphire having a thickness of less than about 50 microns can be an order of magnitude cheaper than the sapphire having a typical thickness. However, this sapphire is extremely difficult to prepare while also maintaining the overall scratch resistance, hardness, and durability of the material. The sapphire layer of the cover plate used in the electronic device of the present invention preferably has mechanical and physical properties similar to thicker sapphire layers. For example, at room temperature, the ultrathin sapphire layer preferably has a flexural strength of at least about 700 MPA, including between about 800 and 1000 MPa, a fracture toughness (i.e., the ability of the material containing a crack or scratch to resist fracture) of greater than 1 MPa, including between about 2 and 5 MPa, a Knoop hardness of greater than about 15 GPa, including between about 17 and about 20 GPa, and/or a Vickers hardness of greater about 1000 kg/m, including between about 2000 and 3000 kg/m. The modulus, such as the Young's modulus, is also similar to the modulus of sapphire, which is typically between about 300-400 GPa, but can vary depending on the desired properties of the cover plate (such as touch sensitivity).

[0018] The sapphire layer of the cover plate can be any sapphire material known in the art. For example, it is known that sapphire may include one of several different crystalline axes, such as the c-axis, the m-axis, or the a-axis, and the properties of a sapphire layer vary depending on this crystal orientation. The sapphire layer used in the present invention can have any known crystalline orientation, as well as off-axis orientations (such as between about 0 and 18 degrees off-axis). Furthermore, the sapphire layer can be prepared using a variety of different methods. For example, the sapphire layers can be prepared by cutting or slicing layers from a donor sapphire material and mechanically grinding the resulting material down to the desired thickness. An optional polishing step may be used if needed to remove any unwanted surface defects. Thus, the sapphire layer can be prepared by a method comprising the steps of providing a layer of sapphire having an initial thickness, reducing the layer of sapphire from the initial thickness to a thickness of from about 10 microns to about 500 micron,; and optionally polishing the layer of sapphire. The sapphire layer can be provided by any method known in the art, including sawing, and the thickness of the sapphire layer can be reduced using a variety of different methods, including mechanical grinding. Such a method is particularly useful for sapphire layers having a thickness of greater than about 100 microns, although thinner sapphire layers can also be produced by this method, including 50 microns or even 25 microns. Graphene could then be applied to the reduced- thickness sapphire layer.

[0019] Alternatively, for a sapphire layer having a thickness of from about 50 microns to about 100 microns, the sapphire layer can be prepared using various layer transfer methods known to remove thin layers from a sapphire donor material, including, for example, controlled spalling or ion implantation and exfoliation method, such as the ion implantation/exfoliation method generally described in U.S. Patent Application No. 12/026,530 entitled, "Method to Form a Photovoltaic Cell Comprising a Thin Lamina", filed February 5, 2008 and published as U.S. Patent Application Publication No. 2009/0194162 and U.S. Patent Application No. 13/331,909 entitled, "Method and Apparatus for Forming a Thin Lamina", filed December 20, 2011, both of which are incorporated in their entireties by reference herein, for the fabrication of a photovoltaic cell comprising a thin semiconductor lamina formed of non-deposited semiconductor material. Such an ion implantation/exfoliation method would be more advantageous over current methods of preparing thin wafers by sawing or cutting since the very properties considered desirable about sapphire (hardness and strength) can make it very difficult, time consuming, and costly to cut, grind, and optionally polish. In addition, sawing or cutting methods produce significant kerf losses, wasting valuable material, and cannot reliably be used to produce thin sapphire lamina, particularly ultrathin lamina having a thickness of approximately 50 microns.

[0020] Thus, the sapphire layer can prepared by a method comprising the steps of providing a sapphire donor body of sapphire comprising a top surface and subsequently implanting an ion dosage through the top surface of the donor body. Using this implantation method, a cleave plane is formed beneath the top surface of the donor body, and the sapphire layer can then be exfoliated from the sapphire donor body along this cleave plane. The ion dosage can comprise, for example, hydrogen, helium, or a combination thereof. Implantation conditions can be varied as needed to produce a sapphire lamina having targeted properties, such as thickness and strength. For example, the ion dosage may be any dosage between about 1.0 x 10 1¹4" and 1.0 x 101¹8⁰ H/cnT 2, such as 0.5-3.0 x 101"7

The dosage energy can also be varied, such as between about 500 keV to about 3 MeV. In some embodiments, the ion implantation temperature may be maintained between about 200 and 950°C, such as between 300 and 800°C or between 550 and 750°C. In some embodiments, the implant temperature may be adjusted depending upon the specific type of material and the orientation of the sapphire donor body. Other implantation conditions that may be adjusted may include initial process parameters such as implant dose and the ratio of implanted ions (such as H/He ion ratio). In other embodiments, implant conditions may be optimized in combination with exfoliation conditions such as exfoliation temperature, exfoliation susceptor vacuum level, heating rate and/or exfoliation pressure. For example, exfoliation temperature may vary between about 400°C to about 1200°C. By adjusting implantation and exfoliation conditions, the area of the resulting lamina that is substantially free of physical defects can be maximized. The resulting sapphire layer may be further processed if needed, such as to produce smooth final surfaces. For example, graphene may be provided on the exfoliated sapphire layer. Alternatively, the sapphire donor body may comprise graphene on the top surface, and therefore, the resulting sapphire lamina would comprise graphene after exfoliation. [0021] The sapphire used in either embodiment can be produced using any method known in the art. For example, the sapphire can be prepared in a crystal growth apparatus, which is a high-temperature furnace capable of heating and melting a solid feedstock, such as alumina, in a crucible at temperatures generally greater than about 1000°C and subsequently promoting resolidification of the resulting melted feedstock material to form a crystalline material, such as a sapphire boule. Preferably, the sapphire is prepared in a heat exchanger method crystal growth furnace, in which a crucible comprising alumina feedstock and at least one single crystal sapphire seed is heated above its melting point to melt the feedstock without substantial melting of the seed, and heat is then removed from the crucible using a heat exchanger, such as a helium-cooled heat exchanger, provided in thermal communication with the bottom of the crucible and positioned under the seed. This method has been shown to produce large, high quality sapphire boules from which the sapphire can be readily removed using available methods. For example, the sapphire can be sliced or cut from a cylindrical portion of a sapphire boule and, as such, is provided in wafer form, having a thickness of, for example, greater than about 0.5 mm, such as from about to 1 mm to about 5 mm. A sapphire wafer of this thickness can be used to produce multiple sapphire layers, further reducing cost, and the remaining portion can be resold or recycled for some other application, including as feedstock for producing another sapphire boule.

[0022] In another embodiment, the cover plate comprises a transparent layer, such as a glass layer, a polymeric material layer, or both comprising graphene. In particular, the cover plate may comprise a sapphire layer combined with one or more transparent permanent or temporary carrier substrates or layers that provide additional desirable features to the cover plate. For example, the cover plate may further comprise a transparent layer affixed to the sapphire layer. The transparent layer can be any transparent material known in the art including, for example, a layer comprising glass, such as soda-lime, borosilicate, or aluminosilicate glass, including chemically-strengthened alkali aluminosilicate glass (such as the material referred to as Gorilla® glass available from Corning), or a layer comprising a polymeric material, such as a polycarbonate or a polymethacrylate such as polymethyl methacrylate (PMMA). The sapphire layer and the transparent layer may be combined using any technique known in the art, forming an interface in between, including the methods described in U.S. Patent Application No. 12/980,424 entitled, "A Method to Form a Device by Constructing a Support Element on a Thin Semiconductor Lamina", filed December 10, 2010, now U.S. Patent No. 8,173,452, incorporated in its entirety by reference herein. For example, the interface may be formed by bonding with an adhesive layer, thereby affixing the sapphire layer to the surface of the transparent layer. Examples of suitable adhesives include, but are not limited to, polymers or combinations of polymers such as poly(propylene carbonate) (PC), poly(ethylene carbonate) (PEC), or poly(butylenes carbonate) (PBC). Electrostatic adhesion may also be used. In addition, the interface may be formed by thermally bonding the sapphire lamina to the transparent layer, such as through thermal compression bonding at, for example, pressures of from about 5-100 psi, including 40 psi, and temperatures from about 300-500°C, including 400°C. Specific bonding conditions would vary depending on the specific type of transparent layer used. Furthermore, the transparent layer may be fused or melted to the sapphire layer to form an interface, and the temperature will depend on the type of material used as the transparent layer. For example, temperatures for melting a glass substrate to the sapphire may be on the order of 650-1050°C while lower temperatures, such as 110-150°C, would be suitable if the substrate is plastic.

[0023] In a specific embodiment, the transparent layer is a subsurface layer having a front or exterior-facing surface to which the sapphire layer is attached, thereby forming a multilayer composite. The subsurface layer can be thicker or thinner than the sapphire layer, depending on its purpose. For example, the subsurface layer can be relatively much thicker than the sapphire layer in order to provide improved strength, particularly when the sapphire layer has a thickness of less than about 200 microns. For example, the subsurface layer can be a glass having a thickness of greater than 0.2 mm, including greater than 0.3 mm or 0.4 mm, such as between about 0.3 mm to about 1.0 mm. By combining a thicker subsurface layer with the thin sapphire layer for the cover plate of the electronic device of the present invention, the composite would retain the desirable surface characteristics of the sapphire, such as hardness and scratch and smudge resistance, while also taking advantage of the desirable bulk properties of the subsurface material, such as good fracture resistance and low cost. For example, in a sapphire-glass composite structure, the sapphire would enhance the shatter and scratch resistance of the glass while, for a sapphire -polymeric material composite, the combination would be much more resistant to mechanical damage, such as cracking. Such composites would not compromise the transparency of the cover plate. Other advantageous combinations of these thin sapphire layers and transparent substrates are also possible and can be determined by one of ordinary skill in the art, given the benefit of this disclosure. [0024] In another specific embodiment, the transparent layer affixed to the sapphire layer is an exterior surface coating layer. Thus, while preferably, the sapphire layer is the exterior layer of the cover plate and the electronic device, an antireflective and/or oleophobic or hydrophobic coating, or other desirable exterior transparent layer may also be applied to the sapphire layer. Typically this exterior transparent surface coating layer has a thickness of less than 2 microns, such as between about 0.001 microns to about 1.5 microns.

[0025] The cover plate may further comprise at least one transparent conducting oxide layer. This is particularly preferred for an electronic device including a capacitive touch screen in the display element in which the touch screen electrical components are integrated with the cover plate. Use of a cover plate comprising a sapphire lamina having a thickness of from about 10 microns to about 500 microns could facilitate simpler integration of a capacitive touch screen into a display. For example, a capacitive touch screen structure in general consists of two layers of transparent conducting oxide (TCO), often separated by a dielectric layer. The two TCO layers are typically patterned into lines, with the lines on the first layer running perpendicular to the lines on the second layer, although other line patterns are also possible. The pitch of these patterned lines may be between 0.1 and 10 mm (such as 6 mm), and the width of these patterned lines may be between 0.2 and 6 mm (such as 5.9 mm or 1 mm). The dielectric layer can be a layer of glass, or, alternatively, may be a sputtered thin film, leading to a configuration having an overall thinner structure.

[0026] A specific example of an embodiment of the present invention, in which the cover plate comprises a sapphire layer, and the sapphire layer comprises graphene on an exterior-facing surface, is shown in FIG 1. Thus, sapphire layer 110 has surface 120 that faces towards the exterior of cover plate 100, and this exterior-facing surface comprises graphene 130. As described above, it is preferred that the sapphire layer is an exterior layer of the cover plate and the electronic device, and therefore, for this preferred embodiment, the exterior surface of this exterior layer comprises graphene 130. This embodiment is particularly useful for providing increased surface toughness and impact resistance to the exterior sapphire layer, especially when the layer is very thin, such as less than 200 microns. The exterior-facing surface comprising graphene may further include an anti-reflective layer, as described above (not shown). As shown in FIG 1, cover plate 100 further comprises transparent subsurface layer 140. When combined with a transparent subsurface layer, such as a glass or polymeric layer as described above, a cover plate having significantly improved mechanic strength can result, without loss of transparency. [0027] As noted above, alternatively or in addition, the cover plate may comprise at least one layer, such as a sapphire layer, having an interior-facing surface that comprises graphene. This embodiment can be particularly useful for improving the touch sensitivity of the cover plate, especially when used in combination with a TCO/thin dielectric/TCO structure. In addition, graphene can be used as a replacement for a TCO structure due to its high conductivity and very low resistivity.

[0028] In addition, the cover plate may comprise at least one layer, such as a sapphire layer, having both an exterior and an interior-facing surface comprising graphene. By providing graphene to both surfaces of a layer of the cover plate, particularly a sapphire layer, significant improvements in both flexural strength and impact resistance would be expected, especially for extremely thin sapphire layers, such as a lamina having a thickness of less than 100 microns. Graphene would be expected to reinforce ultrathin layers of sapphire, without detracting other desirable sapphire properties, including transparency.

[0029] Furthermore, the cover plate may comprise at least one layer, such as a sapphire layer, having edge surfaces comprising graphene. The edges can be the only surfaces comprising graphene or in combination with exterior and/or interior facing surfaces also comprising graphene. Providing graphene on the edges would improve the chip and fracture strength of the cover plate layer. The thicker the layer, the more useful graphene is on the edge surfaces.

[0030] The cover plate comprising graphene can be prepared using any method known in the art. For example, graphene can be produced by a variety of chemical deposition or epitaxial growth methods, including, for example, chemical vapor deposition (CVD) processes, and deposited or grown on the cover plate. Thus, for example, when the cover plate comprises at least one sapphire layer, the sapphire layer comprising graphene can be prepared by providing a layer of sapphire having a thickness of from about 10 microns to about 500 microns and depositing or growing graphene on one or more surfaces of the sapphire layer. Alternatively, single separate layers of graphene can also be prepared by exfoliation methods, including, for example, by exfoliation of graphite. Thus, the sapphire layer comprising graphene can be prepared by attaching a layer of graphene to one of more surfaces of the sapphire layer. Other methods will be known to one of ordinary skill in the art.

[0031] The foregoing description of preferred embodiments of the present invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings, or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents.

[0032] What is claimed is:

Claims

1. An electronic device comprising a cover plate having at least one transparent display region, wherein the cover plate comprises graphene.

2. The electronic device of claim 1, wherein the cover plate has at least one surface comprising graphene.

3. The electronic device of claim 1, wherein the surface is an exterior-facing surface.

4. The electronic device of claim 1, wherein the surface is an interior-facing surface.

5. The electronic device of claim 1, wherein the cover plate has one or more edge surfaces comprising graphene.

6. The electronic device of claim 1, wherein the cover plate comprises one or more layers, and wherein at least one layer comprises graphene.

7. The electronic device of claim 6, wherein at least one layer is a sapphire layer.

8. The electronic device of claim 7, wherein the sapphire layer has a thickness of from about 10 microns to about 500 microns.

9. The electronic device of claim 7, wherein the sapphire layer has a thickness of from about 25 microns to about 500 microns.

10. The electronic device of claim 7, wherein the sapphire layer has a thickness of from about 50 microns to about 500 microns.

11. The electronic device of claim 7, wherein the sapphire layer has a thickness of from about 50 microns to about 400 microns.

12. The electronic device of claim 7, wherein the sapphire layer has a thickness of from about 50 microns to about 250 microns.

13. The electronic device of claim 7, wherein the sapphire layer has a thickness of from about 10 microns to about 100 microns.

14. The electronic device of claim 7, wherein the sapphire layer has a thickness of from about 25 microns to about 100 microns.

15. The electronic device of claim 7, wherein the sapphire layer has a thickness of less than 50 microns.

16. The electronic device of claim 7, wherein the sapphire layer has a thickness of less than 30 microns.

17. The electronic device of claim 7, wherein the sapphire layer has a thickness of less than 25 microns.

18. The electronic device of claim 7, wherein the sapphire layer has a thickness of less than 15 microns.

19. The electronic device of claim 1, wherein the cover plate is one free-standing sapphire layer.

20. The electronic device of claim 7, wherein the cover plate comprises more than one sapphire layer.

21. The electronic device of claim 7, wherein the sapphire layer is an exterior layer of the cover plate.

22. The electronic device of claim 7, wherein the sapphire layer has an exterior-facing surface comprising graphene.

23. The electronic device of claim 7, wherein the sapphire layer has an interior-facing surface comprising graphene.

24. The electronic device of claim 22, wherein the sapphire layer further has an interior- facing surface comprising graphene.

25. The electronic device of claim 7, wherein the sapphire layer has one or more edge surfaces comprising graphene.

26. The electronic device of claim 6, wherein at least one layer is a glass layer.

27. The electronic device of claim 26, wherein the glass is soda-lime glass.

28. The electronic device of claim 26, wherein the glass is a borosilicate glass.

29. The electronic device of claim 26, wherein the glass is an aluminosilicate glass.

30. The electronic device of claim 29, wherein the aluminosilicate glass is a chemically- strengthened alkali aluminosilicate glass.

31. The electronic device of claim 26, wherein the sapphire layer has an exterior-facing surface comprising graphene.

32. The electronic device of claim 26, wherein the sapphire layer has an interior-facing surface comprising graphene.

33. The electronic device of claim 32, wherein the sapphire layer further has an interior- facing surface comprising graphene.

34. The electronic device of claim 26, wherein the sapphire layer has one or more edge surfaces comprising graphene.

35. The electronic device of claim 6, wherein at least one layer is a polymeric material layer.

36. The electronic device of claim 35, wherein the polymeric material is a polycarbonate.

37. The electronic device of claim 35, wherein the polymeric material is a polymethacryate.

38. The electronic device of claim 35, wherein the sapphire layer has an exterior-facing surface comprising graphene.

39. The electronic device of claim 35, wherein the sapphire layer has an interior-facing surface comprising graphene.

40. The electronic device of claim 39, wherein the sapphire layer further has an interior- facing surface comprising graphene.

41. The electronic device of claim 35, wherein the sapphire layer has one or more edge surfaces comprising graphene.

42. The electronic device of claim 7, wherein the sapphire layer is affixed to a glass layer.

43. The electronic device of claim 7, wherein the sapphire layer is affixed to a polymeric material layer.

44. The electronic device of claim 1, wherein the electronic device further comprises at least one display element having a display surface and wherein the cover plate is affixed to the display surface.

45. The electronic device of claim 1, wherein the electronic device further comprises at least one display element having a display surface and wherein the cover plate is a protective layer removably positioned on top of the display surface.

46. The electronic device, of claim 1, wherein the electronic device is an electronic media player, a mobile telephone, a personal data assistant, a pager, a tablet, a laptop computer, or an electronic notebook

47. The electronic device of claim 1, wherein the sapphire layer comprises single crystal sapphire prepared in a crystal growth furnace.

48. The electronic device of claim 47, where the crystal growth furnace is a heat exchanger method furnace.

49. The electronic device of claim 1, wherein the sapphire layer is prepared by a method comprising the steps of:

i) providing a layer of sapphire having an initial thickness;

ii) reducing the layer of sapphire from the initial thickness to a thickness of from about 25 microns to about 500 microns; and

iii) optionally polishing the layer of sapphire.

50. The electronic device of claim 49, wherein the layer of sapphire is reduced by mechanical grinding.

51. The electronic device of claim 1, wherein the sapphire layer has a thickness of from about 10 microns to about 100 microns and is prepared by a method comprising the steps of: i) providing a sapphire donor body having a top surface;

ii) implanting through the top surface of the sapphire donor body with an ion dosage to form a cleave plane beneath the top surface; and

iii) exfoliating the sapphire layer from the sapphire donor body along the cleave plane.

The electronic device of claim 51, wherein the ion dosage comprises hydrogen ions.

The electronic device of claim 51, wherein the ion dosage comprises helium ions.

54. The electronic device of claim 51, wherein the top surface of the sapphire donor body comprises graphene.

55. The electronic device of claim 1, wherein the sapphire layer comprises graphene grown by chemical vapor deposition on a surface of the sapphire layer.

56. The electronic device of claim 1, wherein the sapphire layer comprises a graphene layer attached to a surface of the sapphire layer.

57. A cover plate of an electronic device, the cover plate having at least one transparent display region, wherein the cover plate comprises graphene.

58. The electronic device of claim 57, wherein the cover plate has at least one surface comprising graphene.

59. The electronic device of claim 57, wherein the surface is an exterior-facing surface.

60. The electronic device of claim 57, wherein the surface is an interior-facing surface.

61. The electronic device of claim 57, wherein the cover plate has one or more edge surfaces comprising graphene.

62. The electronic device of claim 57, wherein the cover plate comprises one or more layers, and wherein at least one layer comprises graphene.

63. The electronic device of claim 62, wherein at least one layer is a sapphire layer.

64. The cover plate of claim 63, wherein the cover plate comprises more than one sapphire layer each having a thickness of from about 10 microns to about 500 microns.

65. The cover plate of claim 63, wherein the sapphire layer is free-standing.