AND PHOTOSENSITIVITY

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/487,483 filed April 20, 2017, and U.S. Provisional Patent Application No. 62/593,516 filed December 1, 2017. The entire contents of each of the above-referenced disclosures are specifically incorporated herein by reference without disclaimer.

FIELD OF THE DISCLOSURE

[0002] The instant disclosure relates to electronic devices. Portions of this disclosure relate to thin film materials for energy storage.

BACKGROUND

[0003] Photodetectors are devices that can detect light and convert light to an electronic signal. Some photodetectors can discriminate colors or wavelengths of light that are detected. One application for a photodetector is as an image sensor. Although some photodetectors detect visible light, some photodetectors may detect other wavelengths of light such as infrared light. Photodetectors require power to detect light and generate an electrical signal. That is, a photodetector must be provided a power supply current such that the photodetector can interact with the power supply current and ambient light to produce an electrical signal proportional to the ambient light. The power supply current is produced from energy storage devices, such as batteries or fuel cells. The requirement to integrate an energy storage device with a photodetector in an electronic device places limits on the operation and size of the electronic device. Energy storage, in the form of a battery, can occupy much of the volume within an electronic device and thus place constraints on device size. An amount of energy stored in the device places constraints on device runtime, or how often the device needs to be recharged. Furthermore, higher sensitivity photodetectors may require higher amounts of power supply current, limiting the possible resolution of a photodetector based on available power. The limitations and problems described above are only some issues that accompany the use of photodetectors and are presented as examples of the need for improved electrical components, such as photodetectors. SUMMARY

[0004] A photodetector may be integrated with a microsupercapacitor to form an electronic device, such that the photodetector may be powered by the microsupercapacitor. A thin film material may be shared between the photodetector and the microsupercapacitor when the two are integrated to reduce size and cost of constructing the electronic device. The thin film layer may include a two-dimensional nanomaterial with electrochemical activity that is also photosensitive. The photosensitivity allows the thin film layer to operate as part of a photodetector. The electrochemical activity allows the thin film layer to operate as an electrode of a microsupercapacitor. Although the photodetector is described as integrated with a microsupercapacitor, the photodetector may be independently operated in some modes, such as a stand-alone photodetector, without the presence of the microsupercapacitor changing its operation. For example, the photodetector may be operated from an external power source in some modes. Embodiments described herein address certain shortcomings but not necessarily each and every one described here or known in the art. Furthermore, embodiments described herein may present other benefits than, and be used in other applications than, those of the shortcomings described above. [0005] A microsupercapacitor as referred to with some examples of the disclosed electronic devices refers to an integrated electrochemical capacitor built on a supporting substrate. A microsupercapacitor may be constructed by, for example, depositing and patterning layers of materials on the substrate, including a solid or gel electrolyte.

[0006] The photodetector-supercapacitor devices may be constructed on a substrate, either rigid or flexible, by forming 2D nanosheets of transition metal chalcogenides (TMCs) (e.g., M0S2 and WS2) on transition metal oxides (TMOs) (e.g., M0O3 and WO3). The 2D TMCs may be grown in a controllable manner through an in-situ ion exchange process to obtain a desired thickness for the 2D TMCs. Prior to the ion exchange process a topotactic transformation may be performed to obtain a suitable base for the 2D TMCs from a TMO. For example, a TMO of M0O3 may be transformed to M0O2. Then, an ion exchange process may be performed to form 2D TMCs of M0S2 on the M0O2 surface.

[0007] In some aspects, an apparatus comprising an embodiment of the disclosure may be an electronic device, such as a light-wave communication device, and may comprise an electronic component, wherein the microsupercapacitor is configured to power the electronic component. In some aspects, the thin film layer may comprise at least one of layered inorganic materials, transition metal dichalcogenides (such as sulfide, selenide, telluride), phosphides, or carbon-based materials (such as graphene). In some aspects, the thin film layer may comprise a hybrid of two or more layered inorganic materials or transition metal dichalcogenides (such as sulfide, selenide, or telluride). In some aspects, the thin film layer may comprise materials with photosensitivity in near infra-red wavelengths, infra-red wavelengths, or ultraviolet wavelengths. In some aspects, the thin film layer is in contact with an electrolyte of the microsupercapacitor. In some aspects, the thin film layer may be manufactured on a flexible substrate according to one of coating, and vacuum processing, solution-based processing, and printing.

[0008] The foregoing has outlined rather broadly certain features and technical advantages of embodiments of the present invention in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter that form the subject of the claims of the invention. It should be appreciated by those having ordinary skill in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same or similar purposes. It should also be realized by those having ordinary skill in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. Additional features will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended to limit the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS [0009] For a more complete understanding of the disclosed system and methods, reference is now made to the following descriptions taken in conjunction with the accompanying drawings.

[0010] FIG. 1 is a block diagram illustrating an integrated microsupercapacitor and photodetector according to some embodiments of the disclosure. [0011] FIG. 2 is a flow chart illustrating an example method of operating an integrated microsupercapacitor and photodetector by powering the photodetector with the microsupercapacitor according to some embodiments of the disclosure.

[0012] FIG. 3 is a top-down view of a two-dimensional representation of a self-powered photodetector with two materials in an in-plane interdigital arrangement according to some embodiments of the disclosure.

[0013] FIG. 4 is a top-down view of a two-dimensional representation of a self-powered photodetector with a composite material in an in-plane interdigital arrangement according to some embodiments of the disclosure.

[0014] FIG. 5 is a graph on a linear scale illustrating an example current-voltage (I-V) relationship for a photodetector integrated with a microsupercapacitor according to some embodiments of the disclosure. [0015] FIG. 6 is a graph on a semi-log scale illustrating an example current-voltage (I-V) relationship for a photodetector integrated with a microsupercapacitor according to some embodiments of the disclosure.

[0016] FIG. 7 is a graph illustrating an example photocurrent generated by a photodetector integrated with a microsupercapacitor according to some embodiments of the disclosure. [0017] FIG. 8 is an example process for formation of two-dimensional transition metal chalcogenide on a transition metal oxide according to some embodiments of the disclosure.

[0018] FIGs. 9A-9C are illustrations of an example process for forming a photodetector- supercapacitor device according to some embodiments of the disclosure.

[0019] FIG. 10A shows capacitance-voltage (C-V) curves recorded at different scan rates within the potential range of 0-0.7V according to some embodiments of the disclosure.

[0020] FIG. 10B shows galvanostatic charge-discharge curves for symmetric supercapacitors at different constant current densities according to some embodiments of the disclosure.

[0021] FIG. IOC shows areal capacitance calculated at different current densities according to some embodiments of a capacitor device.

[0022] FIG. 11 shows a photodetector signal measured from a 2D TMC of M0S2 on M0O2 thin films according to some embodiments of the disclosure.

[0023] FIG. 12 is a graph showing an x-ray diffraction result illustrating one embodiment of hexagonal SnSe ₂ nanosheets generated by hydrothermal synthesis. [0024] FIG. 13 is a graph showing current-voltage (I-V) characteristics for a SnSe ₂ photodetector according to some embodiments of the invention.

[0025] FIG. 14 is a graph showing current-voltage (I-V) characteristics for a SnSe ₂ photodetector according to some embodiments of the invention.

[0026] FIGS. 15A-C are illustrations showing the generation of a voltage from impinging light on a nanosheet according to some embodiments of the invention. DETAILED DESCRIPTION

[0027] FIG. 1 is a block diagram illustrating an integrated microsupercapacitor and photodetector according to some embodiments of the disclosure. An apparatus 100 includes a microsupercapacitor formed from a first electrode 102 and a second electrode 104 separated by an electrolyte 106. The first electrode 102 may include a material with photosensitivity and electroactivity, such that the apparatus 100 operates as a photodetector and a microsupercapacitor. The material may be a two-dimensional material, such as a nanosheets, which may be combined with other materials that provide support or additional functionality. For example, the first electrode 102 may include a 2-D nanomaterial to have photosensitivity that causes a reaction in the first electrode 102 in response to impinging light 112 as shown in reaction 122. The first electrode 102 may also have electroactivity at an interface 124 between the first electrode 12 and the electrolyte 106 allowing operation as a microsupercapacitor. Example materials for a thin film layer in the first electrode 102 exhibiting photosensitivity and electroactivity include layered inorganic materials, transition metal dichalcogenides (such as sulfide, selenide, telluride), phosphides, or carbon-based materials (such as graphene). Specific example materials include NbSe ₂ and SnSe ₂ . The structure of apparatus 100 with two or more electrodes may be configured as a fuel cell. In some embodiments, no reference electrode may be needed for operation of the apparatus 100 or the microsupercapacitor. In some embodiments, a patterned gold layer may be deposited on the first electrode 102, and the patterned gold layer may be configured to measure current generated at the photodetector by coupling to appropriate electronic circuitry. Photosensitivity of the first electrode 102 to different wavelengths of light may be determined based on types of materials used in the electrode. The first electrode 102 may have broadband photosensitivity such that all impinging light causes generation of electrical current, although different efficiencies for current generation may exist at different wavelengths. The first electrode 102 material may alternatively be selected to have photosensitivity to specific wavelengths, such as visible light or near infrared (NIR) light. In some embodiments, the first electrode 102 may be divided into two or more structures of different materials to obtain sensitivity to two or more specific wavelengths of light. In some embodiments, a portion of the first electrode 102 material may be a composite material of two or more materials to obtain sensitivity to multiple wavelengths of light.

[0028] Operation of an integrated device shown in FIG. 1 allows for the sharing of a thin film layer operating as first electrode 102 between a microsupercapacitor and a photodetector. FIG. 2 is a flow chart illustrating an example method of operating an integrated microsupercapacitor and photodetector by powering the photodetector with the microsupercapacitor according to some embodiments of the disclosure. A method 200 includes powering a photodetector from a microsupercapacitor at block 202. Then, at block 204, light is received at a two-dimensional nanomaterial thin film layer on a substrate functioning as a photodetector. For example, the first electrode 102 may include the two-dimensional nanomaterial thin film layer. A nanomaterial thin film layer may be a thin film of approximately 1-1000 nanometers. The received light may be converted at block 206 to electrical charge in a photodetector made of the two-dimensional nanomaterial thin film layer. That electrical charge may be stored measured by appropriate electronic circuitry coupled to the photodetector.

[0029] One configuration for the thin film layer operating as an electrode of a microsupercapacitor is as an in-planar interdigital device. FIG. 3 is a top-down view of a two- dimensional representation of a self-powered photodetector with two materials in an in-plane interdigital arrangement according to some embodiments of the disclosure. Although self- powered embodiments are described, the devices can also be powered from alternative or supplemental power sources coupled to the photodetector. Furthermore, the microsupercapacitor may be used to power other electronic components other than the photodetector. An apparatus 300 may include first electrode structures 302 A, 302B of a first material and second electrode structures 304 A, 304B of a second material. The structures 302A-B and 304A-B may be used as, for example, the first electrode 102 in the apparatus 100 such that a microsupercapacitor is formed by the electrode structures 302A-B and 304A-B, electrolyte 206, and another electrode (not shown in FIG. 3). The first electrode structures 302A-B include multiple digits, or branches, that alternate with digits of another electrode structure to form an interdigital structure.

[0030] The electrode structures 302A-B may include contact pads at ends of the digital structures to provide electrical contact to the digital structures to measure current through or resistance of the electrode structures. The resistance or current measurements may provide information regarding light detected by the photodetector through the electrode structures. The electrode structures 302A-B and 304A-B may be operated as independent photodetectors in an array of photodetectors to allow detection of different wavelengths via different channels on one setup. For example, the electrode structures 302A and 304A may be sampled through separate sense circuitry or through different channels coupled to shared sense circuitry. Each channel may provide information regarding different wavelengths of light. In some embodiments, there are no reference electrodes in the apparatus 300. In some embodiments, photodetector performance can be measured at zero bias voltage. The electrode structures may alternatively be coupled together in series or parallel to operate together. The first material of the electrode structures 302A-B and the second material of the electrode structures 304A-B may be different materials, and the materials may be selected to obtain photosensitivity to particular wavelengths of light. For example, NbSe ₂ electrodes may be used for NIR photodetection and SnSe ₂ electrodes may be used for visible light photodetection. In some embodiments, one or more of the electrode structures 302A-B and 304A-B may be a composite material of two materials having different photosensitivities. For example, NbSe ₂ and SnSe ₂ composite electrodes may provide broadband photodetection from visible to NIR wavelengths. A wavelength- selective (e.g., single wavelength) photodetector with symmetric microsupercapacitor can be fabricated with a single two-dimensional material. A broadband photodetector with asymmetric microsupercapacitor can be fabricated with two or more different two-dimensional materials. A broadband photodetector may measure light from ultraviolet (UV) to near infrared (NIR) wavelengths with a symmetric microsupercapacitor structure by using two or more different 2D material composites. In some embodiments, the photodetector performance may be measured at zero bias voltage.

[0031] FIG. 4 is an example of a device in which all electrode structures are a composite material. FIG. 4 is a top-down view of a two-dimensional representation of a self-powered photodetector with a composite material in an in-plane interdigital arrangement according to some embodiments of the disclosure. A device 400 includes electrode structures 402A, 402B forming an interdigital structure over, or otherwise located and in contact with, electrolyte 406 to form an electrode of a microsupercapacitor. One example composite material for the structures 402A-B is a composite of NbSe ₂ and SnSe ₂ , which may have broadband light absorption.

[0032] The structures of FIG. 3 and FIG. 4 may be manufactured by a variety of processes. Two-dimensional nanosheets of NbSe ₂ and SnSe ₂ or other materials may be prepared by liquid phase exfoliation and incorporated into an electronic device with an integrated microsupercapacitor and photodetector. Thin NbSe ₂ and SnSe ₂ films can be fabricated on rigid or flexible substrates with spin coating, layer-by-layer coating, dip coating, spray coating, inkjet printing and vacuum filtration methods, vacuum processing, and/or solution-based processing. The in-planar interdigital structure of thin NbSe ₂ and SnSe ₂ films can be prepared by lithography and laser scribing methods. The nanosheets may also be prepared by hydrothermal synthesis. For example, SnSe ₂ may be prepared using hydrothermal synthesis from SnCL ₄ and NaBH ₄ at a temperature of 180 degrees Celsius for 24 hours. Different temperatures or times may be used to obtain difference characteristics. Longer times may generate thicker sheets. Processing at 180 degrees Celsius may generate hexagonal SnSe ₂ nanosheets, and processing at 220 degrees Celsius may generate oxidized Se rods formed with SnSe ₂ . FIG. 12 is a graph showing an x-ray diffraction result illustrating one embodiment of hexagonal SnSe ₂ nanosheets generated by hydrothermal synthesis. Electrical measurements of SnSe ₂ manufactured by hydrothermal synthesis are shown in FIG. 13 and FIG. 14. The electrical measurements show that the SnSe ₂ nanosheets are useful as a photodetector operating as shown in FIGS. 15A-C.

[0033] In the example electrodes of FIG. 1, FIG. 3, and FIG. 4, electron-hole pairs can be generated when two-dimensional materials in thin films of the electrodes are illuminated by light with energy equal to or larger than the material's energy gap. These photoexcited electron-hole pairs may separate during the charging and discharging processes of the two- dimensional material electrodes. In this manner, many different two-dimensional materials and configurations may be used as wavelength- selective photodetectors as well as a microsupercapacitor electrode. Example materials for the two-dimensional material include graphene (e.g., Graphene, graphitic carbon Nitride), transition metal chalcogenides (e.g., NbSe ₂ , NbS ₂ , SnSe ₂ , SnS ₂ , MoS ₂ , MoSe ₂ , WS ₂ , WSe ₂ , TiS ₂ , NiSe ₂ , ZrTe ₂ ), transition metal oxides (e.g., MoCb, WO3, SnO, Ti0 ₂ , Mn0 ₂ , Ru0 ₂ , V ₂ Os), Group III layered semiconductors (e.g., GaSe, GaS, InSe, Bi ₂ S ₃ ), and others such as MXenes, Black Phosphorous.

[0034] Example characteristics of a photodetector device with two-dimensional MoS ₂ nanosheets as the two-dimensional thin film layer are shown in FIG. 5, FIG. 6, and FIG. 7 illustrating the capability of an example integrated photodetector and microsupercapacitor device. FIG. 5 is a graph with lines 502 and 504 on a linear scale illustrating an example current-voltage (I-V) relationship for a photodetector in the dark and light, respectively, according to some embodiments of the disclosure. FIG. 6 is a graph with lines 602 and 604 on a semi-log scale illustrating an example current-voltage (I-V) relationship for a photodetector in the dark and light, respectively, according to some embodiments of the disclosure. FIG. 7 is a graph with line 702 illustrating an example photocurrent generated by a photodetector integrated with a microsupercapacitor according to some embodiments of the disclosure. The photocurrent of line 702 is shown to linearly increase with increasing light intensity due to photo-excited carriers in the exfoliated M0S2 nanosheets.

[0035] In some embodiments, the combined photodetector and capacitor may be formed by in-situ growth of two-dimensional transition metal chalcogenide (TMCs) from transition metal oxides (TMOs). This in-situ growth may be performed by creating a transition metal dioxide from a topotactic transformation of a transition metal trioxide. Although a topotactic transformation is described, other processes may be used to prepare a base material for growth of the TMCs. The TMCs may then be grown on the top of the transition metal dioxide with controllable thickness as a function of time using, for example, in-situ ion exchange process. The transition metal chalcogenide/oxides can function as both photosensitive element and electroactive element that generates electric current in response to light or electrochemical events. An example of such a process is illustrated in FIG. 8.

[0036] FIG. 8 is an example process for formation of two-dimensional transition metal chalcogenide on a transition metal oxide according to some embodiments of the disclosure. An initial material may be, for example, transition metal oxide (TMO) 802, such as M0O3. A topotactic transformation forms transition metal dioxide 804, such as M0O2, from the TMO 802. In some embodiments, a M0O2 base is prepared from a topotactic transformation of M0O3 by sprinkling 1 gram of M0O3 powders on an AI2O3 boat placed in a quartz chamber, introducing argon gas (e.g., at 40 seem) into the chamber until heated to 600 °C, and then injecting hydrogen gas (e.g., at 10 seem) into the chamber and held at 600 °C for 3 hours, after which the powder is allowed to cool naturally in atmospheric argon flow.

[0037] Then, a growth process forms 2D TMC 806 on the transition metal dioxide 804, such as to obtain a M0S2/M0O2 material stack. The growth process may be an ion exchange process that increases the thickness of 2D TMC 806 over time, such that varying thicknesses of 2D TMC 806A-D may be obtained based on the processing time. In some embodiments, 2D TMCs of M0S2 on M0O2 are prepared using an in-situ ion-exchange process. An example of such a process includes dispersinglOO milligrams of M0O2 powders into 40 mL 1M NaHS aqueous solution. Then, the solution is stirred at room temperature for 12 hours. Next, the samples are collected and annealed at 300 °C in Argon for 2 hours to obtain crystalline 2D M0S2 TMCs on the M0O2 base structure. [0038] The process of FIG. 8 allows the large-scale growth of 2D TMC nanosheets on TMOs. Although specific examples of M0S2/M0O2 material stacks are provided, other embodiments may involve other TMO/TMC materials. Example TMOs include M0O3, WO3, SnO, T1O2, Mn0 ₂ , RuCh, V2O5, or other electroactive transition metal oxides. Example TMCs include M0S2, MoSe ₂ , MoTe ₂ , WS2, WSe ₂ , WTe ₂ , SnSe ₂ , SnS ₂ , T1S2, NiSe ₂ , ZrTe ₂ .

[0039] The material stack may be patterned to form a photodetector-supercapacitor device. For example, the M0S2/M0O2 material stack formed from topotactic transformation and ion exchange processes may be patterned into an interdigital structure such as a structure like that shown in FIG. 4. FIGs. 9A-9C are illustrations of an example process for forming a photodetector-supercapacitor device according to some embodiments of the disclosure. Interdigital structures 902 and 904 may be patterned from the material stack as shown in FIG. 9A. The structures 902 and 904 may take other shapes than that illustrated. The structures 902 and 904 are configured to form electrodes of a capacitor, which is completed when electrolyte is deposited between the structures 902 and 904. Next, metal features 906 may be formed on the material stack. The metal features 906 may be used as electrodes for photodetection. Next, an electrolyte 908 may be deposited between the interdigital structures 902 and 904 to provide capacitance for the device. [0040] Under illumination, photo-excited electrons from the semiconducting two- dimensional nanosheets of transition metal chalcogenides produce a self-charging current. The transition metal oxides electrically coupled to the 2D TMCs store the photo-generated electrical signals in capacitive structure. The capacitive structure may then be used to power other devices and function as an electrical energy delivery output source for various applications. In some embodiments, the current produced from the two-dimensional nanosheets may be used as a bias signal for an attached photodetector. The current may be used as a bias signal independent of a charging of the capacitive structure. Thus, for example, the capacitive structure may be pre-charged via a direct charge from another power source, such as a piezoelectric, triboelectric, or thermoelectric material. [0041] The supercapacitor performance of various kinds of such TMOs and the photoactive performance of TMCs combine in these embodiments to form a transition metal chalcogenide/oxides-based supercapacitor as a photodetector with in-planar interdigital structure for the large-scale fabrication of arrays of the self-powered photodetector- supercapacitor systems. In some embodiments, a supercapacitor-photodetector structure may be configured to convert power from multiple wavelengths of light. For example, M0S2 on M0O2 thin film electrodes can be used for visible light photodetection and MoSe2 on M0O2 electrodes can be used for near infrared (NIR) photodetection. In some embodiments, a supercapacitor-photodetector structure may be configured to operate in broadband light. A broadband photodetector with supercapacitor can be fabricated with the selective area growth of two or more different TMCs on TMO hybrids. For example, growth of M0S2 and MoSe ₂ on M0O2 electrodes provide broadband photodetection from for visible to NIR wavelengths.

[0042] Electrical characteristics of test devices manufactured by an in-situ ion exchange process are shown in FIGs. lOA-C and FIG. 11. FIG. 10A shows capacitance-voltage (C-V) curves recorded at different scan rates within the potential range of 0-0.7V according to some embodiments of the disclosure. The curves 1002, 1004, 1006, 1008, and 1010 are recorded with scan rates of 20, 30, 50, 80, and 100 mV/s, respectively. The C-V curves show a nearly- rectangular shape up to a scan rate of 100 mV/s, which illustrate characteristics for supercapacitors with excellent capacitance behavior and low contact resistance. FIG. 10B shows galvanostatic charge-discharge curves for symmetric supercapacitors at different constant current densities according to some embodiments of the disclosure. Curves 1012, 1014, 1016, 1018, and 1020 are recorded at current densities of 0.2, 0.5, 1.0, 2.0, and 3.0 mAcm ^"2 , respectively. The nearly-symmetric charge-discharge curves indicate a high columbic efficiency for the devices. FIG. IOC shows areal capacitance calculated at different current densities according to some embodiments of a capacitor device. The areal capacitances are calculated based on the charge-discharge curves and areal capacitance of approximately 28mF/cm ² is obtained.

[0043] FIG. 11 shows a photodetector signal measured from a 2D TMC of M0S2 on M0O2 thin films according to some embodiments of the disclosure. Thermal deposition of metal electrodes on the supercapacitor provides arrays of two-terminal, parallel-type photodetector s. After illumination with a visible laser with a wavelength of 532 nm, the photodetecting film became conductive and the photocurrent increases with increasing laser power due to photo- excited carriers in the M0S2. A line 1102 shows a measurement from the photodetector in a dark environment, and a line 1104 shows a measurement from the photodetector under illumination from a 100 mW/cm ² incident laser beam with a wavelength of 532nm. The voltage difference between light and dark provides sufficient separation for processing by electronic circuitry.

[0044] Examples of an electronic device described herein may be used in the large-scale fabrication of devices that can function simultaneously as a microsupercapacitor and a photodetector. The device may operate in a self-powered mode, wherein the photodetector is powered by the microsupercapacitor system, because the microsupercapacitor electrode materials themselves are both light sensitive and electrochemically active. Thus, the device can generate electric current due to photoexcitation, surface charge absorption, and/or electrochemical reactions. The photoexcited electrons from two-dimensional nanosheets of layered materials can provide self-charging of the microsupercapacitor under illumination of appropriate light. The microsupercapacitor may store the photo-generated electrical signals in its capacitive structure, and later deliver the electrical signals in various applications or to self- power the photodetector. Furthermore, simple solution mixing of two or more different two- dimensional nanosheets offers broadband photodetection from UV to NIR. Solution mixing also provides a low-cost alternative to atomic layer deposition (ALD) techniques. Due to the mechanically flexible nature of certain two-dimensional nanosheets of layered materials, the arrays of the photodetector-microsupercapacitor system may be fabricated on plastic and paper substrates, which are beneficial for wearable and patchable applications. Some applications for the electronic devices described herein include imaging techniques and light-wave communications.

[0045] Although the present disclosure and certain representative advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. For example, the described order, steps, operations, and manufacturing processes are indicative of aspects of methods of the invention. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated method. As another example, the terms positive and negative voltages are only relative terms. As one of ordinary skill in the art will readily appreciate from the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.