WO2006022637A1

WO2006022637A1 - Rectifying charge storage device with phototransducer

Info

Publication number: WO2006022637A1
Application number: PCT/US2004/023968
Authority: WO
Inventors: Michael L. Beigel
Original assignee: Precision Dynamics Corporation
Priority date: 2004-07-22
Filing date: 2004-07-22
Publication date: 2006-03-02
Also published as: TW200607073A

Abstract

A rectifying charge storage device (10), consisting of a rectifier (18) and capacitor (14) which share common elements, includes a phototransducer such as a photoconductive or photovoltaic component for producing an electrical signal in response to incident light, or a photoemissive component for producing a light signal (154) in response to an electrical signal (152).

Description

RECTIFYING CHARGE STORAGE DEVICE WITH PHOTOTRANSDUCER

BACKGROUND OF THE INVENTION

This invention relates generally to improvements in and to a rectifying charge storage device of the type having a rectifier and capacitor which share common elements, as described in U.S. Patent 6,414,543 and

U.S. Publication US 2002/0140500 A1. More particularly, this invention relates to an improved rectifying charge storage device having an integrated phototransducer for converting an incident light signal to an electrical signal, or for converting an electrical signal to an emitted light signal. The invention may be used in a variety of phototransduction applications including, but not limited to a photovoltaic power supply or a photoconductive sensor responsive to incident light, or a photoemissive circuit for generating a light signal responsive to an electrical signal.

U.S. Patent 6,414,543 and U.S. Publication US 2002/0140500 A1 , which are incorporated by reference herein, disclose embodiments for a rectifying charge storage element and related electronic circuits suitable for fabrication on various substrates, including flexible substrates, by various means including printing or other deposition techniques using organic conductors, semiconductors and insulators and other electronic materials suitable for deposition and use in electronic circuits. This rectifying charge storage element is disclosed for use as a power supply that extracts DC power (voltage and current) sufficient to power an electronic device from an AC input signal. The AC input signal may be derived from an inductive, capacitive, or L-C resonant circuit coupled to an external AC electromagnetic field or electrostatic AC field. The electronic circuit thus powered may comprise a radio frequency identification (RFID) circuit.

In this regard, most electronic circuits require a source of DC voltage with sufficient current output to power the circuit elements. Many of these circuits derive DC power by rectifying and filtering an AC power signal. Often, the AC signal is provided to the circuitry by electromagnetic coupling. For example, a passive RFID tag system must be capable of receiving power from an RFID reader to the RFID tag via an inductive (H-field) or electric field (E-field) coupling, and transmitting data from the tag to the reader also via inductive or electric field coupling. The activation field frequency for typical RFID devices may range from less than about 100 kHz up to more than about 30 MHz if inductive or capacitive coupling is utilized, and up to the microwave region if electric field RF antenna coupling is used. In current industry practice, operating power to a passive RFID tag or other electronic circuit is derived by utilizing a rectifier device and a charge-storage device, typically a rectifier diode or combination of diodes connected to a charge storage capacitor or combination of capacitors. In the past, these elements have been implemented as separate components within a discrete circuit or silicon integrated circuit. See, for example, U.S. Patent 4,333,072.

Recent advancements in circuitry manufacturing processes, applicable to RFID tag and similar electronic circuit systems, have enabled the production of electronic circuits on flexible substrates using thin film materials such as organic and polymer semiconductors and other substances that can be applied by techniques such as ink jet printing. A primary objective is to produce electronic devices that have operating characteristics similar to discrete or integrated silicon circuit technology sufficient to operate certain types of circuits while approaching the economy of printing processes. See, for example, U.S. Patents 5,973,598 and 6,087,196. The rectifying charge storage device disclosed in the above- referenced U.S. Patent6,414, 543 and U.S. Publication US 2002/0140500 A1 incorporates a rectifier component such as a rectifying diode in combination with a charge storage component such as a capacitor, wherein these components share one or more common elements resulting in a composite device that is particularly suited for economical manufacture as by printing processes or the like. In addition, the composite device is especially suited for support on a flexible substrate which may comprise an integral portion of the device. Moreover, the supporting substrate may also comprise an electrically operative portion of the device. This rectifying charge storage device has many alternative uses in electronic circuitry.

SUMMARY OF THE INVENTION

In accordance with the invention, an improved composite rectifying charge storage device is provided of the type shown and described in U.S. Patent 6,414,543 and U.S. Publication US 2002/0140500 A1 , wherein the composite device incorporates a phototransducer for converting between light and electrical signals. In one form, the phototransducer comprises a light responsive component such as a photoconductive or photovoltaic component for producing an electrical signal in response to incident light. In another form, the phototransducer comprises a photoemissive component for producing a light signal in response to an electrical signal.

In one preferred form of the invention, the composite rectifying charge storage device includes a rectifier such as a diode and a capacitor having a common conductor. The capacitor comprises spaced-apart conductive surfaces or areas defined by this common conductor and a second conductor with a dielectric material therebetween. In one form, the common conductor may comprise the cathode or anode connection to the rectifying diode. The device may be formed as by ink jet printing or the like onto a substrate which may comprise a flexible substrate. The substrate may be provided as a separate component having the rectifying charge storage device formed or mounted thereon. Alternately, the substrate can be formed integrally with the rectifying and charge storage device, for example, by integrating the substrate with the dielectric material.

In one preferred form, the phototransducer comprises a photovoltaic diode responsive to incident radiant energy such as light for generating a charge which can be stored by the capacitor of the composite device. In an alternative preferred form, the phototransducer comprises a photoconductive diode responsive to incident radiant energy such as light for providing a light responsive or variable conductivity to generate an electrical output signal from the composite device, wherein this electrical output signal can be monitored as a representation of an incident light signal.

In a further preferred form of the invention, the phototransducer comprises a photoemissive component such as a light emitting diode (LED) for generating a light output signal in response to an electrical signal coupled to the composite rectifying charge storage device. In this embodiment, the light output signal can be monitored as a representation of the electrical signal, which in turn may represent a monitored parameter such as pressure, temperature, humidity, vibration, sound, magnetic field, or the presence of a target chemical agent, and others.

In a still further preferred form of the invention, the rectifying charge storage device includes a first phototransducer comprising a photoemissive component for generating a light output signal, and a second phototransducer comprising a photoreceptive component responsive to incident radiant energy to generate an electrical output signal. The photoemissive component may comprise a light emitting diode, and the photoreceptive component may comprise a light sensing capacitor.

Alternately, the photoemissive component may comprise a light emitting capacitor, and the photoreceptive component may comprise a light sensing diode. In either configuration, the combined photoemissive/photosensing device may be used in optical scanning and identification systems and the like.

Otherfeatures and advantages of the present invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the invention. In such drawings:

FIGURE 1 is a somewhat schematic perspective view illustrating a composite rectifying charge storage device incorporating a phototransducer in accordance with the present invention;

FIGURE 2 is a circuit diagram illustrating the composite device of FIG. 1 in one form;

FIGURE 3 is a circuit diagram illustrating the composite device of FIG. 1 in an alternative form; FIGURE 4 is a schematic sectional view showing one preferred form of the invention wherein the phototransducer component comprises a photoreceptive component such as a photovoltaic diode;

FIGURE 5 is a circuit diagram illustrating an inductive antenna connected in series with the composite device wherein the phototransducer component comprises a photoemissive component;

FIGURE 6 is a circuit diagram similar to FIG. 5, but showing the composite device connected in parallel with an inductive antenna;

FIGURE 7 is a circuit diagram illustrating a full wave rectifier with inductive antenna; FIGURE 8 is a waveform diagram illustrating operation of the circuit shown in FIG. 7;

FIGURE 9 is a circuit diagram illustrating a bistable edge driven composite device;

FIGURE 10 is a waveform diagram illustrating operation of the circuit of FIG. 9;

FIGURE 11 is a schematic sectional view showing one preferred form of the bistable edge driven composite device of FIG. 9;

FIGURE 12 is a circuit diagram showing a stacked photovoltaic power supply including a plurality of composite devices connected in series relation; FIGURE 13 is a circuit diagram showing a composite device incorporating a photoemissive component for illuminating a surface, and a photoreceptive component for monitoring light reflective from said illuminated surface; FIGURE 14 is a schematic sectional view showing the composite device of FIG. 1 mounted on a flexible substrate;

FIGURE 15 is a somewhat schematic plan view of the device of FIG. 14;

FIGURE 16 is a schematic sectional view similar to FIG. 14, and depicting an alternative preferred form of the invention incorporating a flexible substrate;

FIGURE 17 is a somewhat schematic plan view of the device of FIG. 16;

FIGURE 18 is a schematic sectional view similar to FIG. 14, and illustrating a further alternative preferred form of the invention;

FIGURE 19 is another schematic sectional view similar to FIG. 14, and showing still another alternative preferred form of the invention; and

FIGURE 20 is a schematic plan view depicting yet another alternative preferred form of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in the exemplary drawings, an improved composite rectifying charge storage device referred to generally in FIGURE 1 by the reference numeral 10 incorporates a phototransducer for converting radiant energy such as an incident light signal to an electrical signal, or for converting an electrical signal to an emitted light signal. The invention may be used in a variety of phototransduction applications including, but not limited to a photovoltaic power supply having a photoconductive or photoreceptive sensor responsive to incident light, or a photoemissive circuit for generating a light signal responsive to an electrical signal. The invention may also incorporate both a photoemissive component and a photoreceptive component in a common device.

The improved rectifying charge storage device of the present invention corresponds generally with and represents an improvement upon the power supply device shown and described in parent U.S. Patent 6,414,543 and in copending U.S. Publication US 2002/0140500 A1 , both of which are incorporated by reference herein. In this regard, as viewed in FIG. 1 with respect to one preferred form of the invention, the illustrative rectifying charge storage device 10 generally includes a diode rectifier 12 and a capacitor 14. The diode 12 includes a conductor 16 and a semiconductor 18. A common conductor 20 between the diode 12 and capacitor 14 is superimposed on a dielectric component 22 of the capacitor 14 which, in turn, is mounted on a conductor 24. The conductor 16 is shown electrically connected to one terminal

30 of a suitable AC source 32, and is electrically connected to one surface of the semiconductor 18 at a surface interface 34. The opposite surface of the semiconductor 18 is shown electrically connected to the common conductor 20 at a surface interface 36. The common conductor 20 is connected to the dielectric component 22 at a surface interface 38, and the conductor 24 is connected to the dielectric component 22 at a surface interface 42. The conductor 24 is connected to a second terminal 46 of the AC source 32 and also serves as the ground output terminal 48.

Rectification takes place between the conductor 16, the semiconductor 18, and the common conductor 20 through the interfaces 34 and 36. Charge storage takes place between the common conductor 20, the dielectric component 22, and the conductor 24. The surface area of the rectifying component and 16, 34, 18, 36, and 20 interfaces may if desired be minimized to reduce internal parasitic capacitor characteristics inherent in rectification. The surface area of the capacitive component interface provided by the common conductor 20 may if desired be maximized to increase DC charge storage capacity. In a power supply application, the common conductor 20 provides the DC power at a junction 26 and the circuit being powered by the device 10 may be energized thereby inductively, magnetically, or directly. The diode components may be fabricated from various materials, including inorganic semiconductor nanocrystals such as CdSe, InP, and others. Furthermore, conjugated polymers may be used, such as poly(phenylene-vinylene) (PPV), its derivatives and co-polymers (such as MEH-PPV (poly(2-methoxy, 5-(2'-ethyl-hexoxy)-p-phenylene vinylene))); polyfluorene (PF), its derivatives and co-polymers; polyparaphenylene (PPP), its derivatives and co-polymers; polythiophene (PT), its derivatives and co-polymers; and others.

The rectifying function of the diode 12 is implemented through the conductor 16 which serves as the anode and the common conductor 20 which serves as the cathode. The rectifying character of an organic or a polymeric diode usually requires different conductors with different work functions for the anode and for the cathode. Organic and polymeric semiconductors are usually regarded as semiconductors with low doping concentration (usually in the range of ~10¹³ cm^'3), hence the theory of p-n junction commonly used inorganic semiconductor diodes is not applicable here. For inorganic diodes, metal electrodes for the anode and cathode can be the same material with ohmic contacts to the p-type and n-type semiconductor, respectively. The rectifying behavior is from the p-n junction.

For organic semiconductors, the relative position of the work functions (or the energy level) of the metal electrodes to the energy levels of the conduction band and valence band of the organic semiconductor determines the rectifying behavior. The choice of anode hence is preferentially to be high work function metals such as gold, nickel, and their alloys. Alternatively, some metal oxides, including but not limited to indium tin-oxide, indium oxide, are also candidates for the anode material. For the cathode, the choice is preferentially low work function metals, including but not limited to calcium, lithium, magnesium, and others. Recently, the metal alloys consisting of a small amount of low work function metals, such as aluminum:lithium 3% alloy and 97% AhLiF bilayer electrode, have become alternatives for the choice of cathode material.

The materials for the capacitor dielectric 22 should be insulating materials, preferentially with a high dielectric constant to enhance its capacity. The structure of the capacitor 14 should provide a larger area compared to the diode. The dielectric 22 may be an organic or polymeric or inorganic insulator with reasonable dielectric constant. It should be large enough to hold enough charge, and it should also be small enough such that the device 10 has a fast response time. Currently, polymer materials such as polystyrene, polyethylene, and polycarbonate are ideal candidates. The dielectric 22 should be flexible where the other components of the device 10 are flexible. An organic semiconductor can also be used as the dielectric material provided that the conductors defining the capacitor 14 have the same work function.

Alternative organic semiconductors, referred to a high performance organic semiconductor devices, are shown and described in copending U.S. Serial No. 10/218,141 , filed August 12, 2002, and incorporated by reference herein. In the case where the conductor 16 is formed from a relatively high work function metal such as a thin layer of aluminum or gold, a layer of indium tin oxide or similar lower work function material is used for the common conductor 20. In this configuration, the conductor 16 comprises the anode connection to the semiconductor or diode component 18, with the common conductor 20 comprising the cathode connection to yield a composite device 10 having an electrical schematic as viewed in FIG. 2. Conversely, when the conductor 16 is formed from indium tin oxide or similar material, the common conductor 20 should be formed from a comparatively high work function metal such as aluminum or gold. In this latter configuration, the common conductor 20 comprises the anode connection for the semiconductor 18, and conductor 16 comprises the cathode connection, resulting in a composite device having an electrical schematic as viewed in FIG. 3. In either of these arrangements (FIGS.2 and 3), in accordance with the present invention, the phototransducer is incorporated directly into the composite device 10. The phototransducer may comprise a light responsive or light receptive component such as a photoconductive or photovoltaic component for producing an electrical signal in response to incident light, or the phototransducer may comprise a photoemissive component for producing a light output signal in response to an electrical signal.

More particularly, as viewed in FIGS. 2 and 3, either or both of the diode and capacitor components may comprise a photoreceptive phototransducer driven by incident radiant light as depicted by the dotted line incident light arrow, to produce a light-responsive electrical signal. This electrical signal is thus representative of the incident light signal, and may comprise an indication of the presence or absence of light or variable intensity thereof, for use, e.g. , as a solar cell or photosensor. Alternately, the electrical output signal may comprise a representation of a modulated information-containing incident light signal. Or, in one alternative arrangement, either or both of the diode and capacitor components may incorporate a photoemissive phototransducer for producing a light output signal in response to an electrical signal, as depicted by the solid line photoemissive arrows. Further, if desired, the diode and capacitor components may both incorporate a phototransducer, such as a configuration wherein one component comprises a photoemissive component responsive to an electrical signal to produce a light signal output, and the other component comprises a photoreceptive component responsive to incident light to produce an electrical signal output. Such combined photoemissive/photoreceptive embodiment may be used, for example, in optical scanning and identification systems.

In one illustrative preferred form as shown somewhat schematically in FIG. 1 , the conductor 16 comprises an optically transparent or transmissive conductive material such as a transparent layer of indium tin oxide or the like, or a layer of a selected metal such as aluminum or gold which is thin enough to achieve transparency. The semiconductor 18 comprises a photoreceptive or photoconductive component adapted to conduct an electrical signal in response to incident radiant energy such as light. One exemplary photoconductive component comprises a polyimide film device of the type shown and described in U.S. Patent 5,158,619, which is incorporated by reference herein. Alternative photoconductive components may also be used.

In one alternative preferred form, the phototransducer may comprises a photovoltaic diode component for producing a voltage when exposed to radiant energy such as incident light. In this arrangement, with continued reference to FIG. 1 , the conductor 16 is again formed from a layer of a conductive and optically transparent or transmissive material such as indium tin oxide or the like, and overlies the semiconductor 18 which comprises a photovoltaic unit such as shown and described in U.S. Patent 4,164,431 , which is also incorporated by reference herein. More particularly, FIG.4 illustrates this arrangement in more detail, wherein the semiconductor 18 comprises a multilayer organic composition to include an upper layer 18a comprising an organic electron acceptor compound overlying a lower layer 18b comprising an organic electron donor compound. As shown and described in U.S. Patent 4, 164,431 , at lease one of these materials is capable of absorbing light, and the two materials cooperatively define a rectifying junction. As shown, the conductor 16 is formed as a thin layer overlying the acceptor compound 18a, and the donor compound 18b is formed on the common conductor 20. A transparent protective cover substrate 19 such as glass or a flexible transparent layer of plastic or the like may be provided to extend over the conductor 16 and other components.

In this embodiment of the invention, the multilayer semiconductor 18 is responsive to incident radiant energy to produce a corresponding electrical signal which may be used for power conversion or for processing and transducing an optical information signal. In the case of power conversion, the charge developed across the semiconductor 18 can be stored in the capacitor component. An electrical schematic of this composite device is also represented by the schematic shown in FIG. 2, although a reversal of the anode/cathode connections as previously described results in the electrical schematic of FIG. 3. In a photovoltaic device, the surface area of the photoreceptive component may be optimized as by providing an extended surface area where maximum energy output is desired, or a relative small surface area where faster device response time is desired.

In a further alternative preferred form of the invention, and referring again to FIG. 1 , the phototransducer may comprise a photoemissive component such as a light emitting diode (LED) for producing a radiant energy output signal when the composite device 10 is coupled to an appropriate input signal, such as by connecting the device to the AC source 32, or to an inductive or magnetic field source or the like as by means of a suitable antenna. In this embodiment, the conductor 16 comprises an optically transparent or transmissive thin film conductive material such as indium tin oxide, or other suitable thin and optically transmissive metallic conductor, and the semiconductor 18 comprises a light emitting diode component such as an MEH-PPV polymer semiconductor or the like. In this arrangement, in response to the AC component of a drive signal, the semiconductor 18 emits a light output signal representative of the input signal. An electrical schematic of this composite device is also shown in FIG.

2, with a reversal of the anode/cathode connections as previously described resulting in the electrical schematic of FIG. 3. In one alternative form, the photoemissive diode component may comprise a dual function diode adapted for emitting light when biased in one direction, and adapted for use as a photoreceptive component responsive to incident light when biased in an opposite direction. Such dual function diode components are shown and described in U.S. Patent 5,504,323, which is incorporated by reference herein.

In another alternative preferred form of the invention, the phototransducer component of the composite device may be provided in the form of a photoreceptive or photoemissive capacitor 14. More particularly, a photoemissive capacitor 14 may incorporate an electroluminescent material between the conductors 20 and 24 (FIG. 1), within or forming the dielectric component, wherein such electroluminescent material is photoconductive in response to incident radiant energy such as light. As a result, the capacitance is varied in response to incident light, to correspondingly alter an electrical output from the rectifying charge storage device. Alternately, a photoreceptive capacitor 14 may be provided for converting incident optical energy to electrical energy, wherein the photoreceptive capacitor may be constructed according to Japan Published Appln. JP2002152991 A2, which is also incorporated by reference herein.

The composite rectifying charge storage device 10, incorporating the phototransducer may be utilized in a wide variety of electrical circuits to provide signal conversion between radiant and electrical energy. In this regard, FIG. 5 is a circuit diagram illustrating the composite device 10 connected in series with an antenna 150 for receiving an input (AC) signal in the form of an electromagnetic signal or field 152. FIG. 6 is a circuit diagram showing the composite device 10 connected in parallel with the antenna 150. In these circuit arrangements, the phototransducer may comprise at least one photoemissive component responsive to the input signal to produce or emit an appropriate light output signal 154. This photoemissive component may be designed for emitting light in the presence of a sufficiently strong electromagnetic field, and/or for producing a light modulated information signal proportional and thereby representative of a modulated electromagnetic field. The photoemissive component may comprise the semiconductor component 18, or the capacitor component 14, or both.

FIG. 7 is another circuit diagram wherein a modified composite rectifying charge storage device 210 is provided in a full wave rectifier configuration. As shown, a pair of diode or semiconductor components 18 are connected with an inductive antenna 150 in a center tap arrangement, and are associated with a common capacitor component 14. Related FIG.

8 is a voltage waveform chart wherein the waveform X represents the input signal, and wherein voltages A and B respectively represent threshold voltages for switching the respective diode components to an energized or "on" state when the waveform X exceeds these thresholds. The diode components 18 may be light emitting as illustrated, to generate light each time the waveform X exceeds the associated threshold.

FIG. 9 illustrates a circuit incorporated into a modified composite device 310 to provide a bidirectional edge driven rectifying charge storage device. In this configuration, a pair of diode or semiconductor components 18 are coupled with opposite polarity between an input conductor 16 and a common conductor 20 comprising one plate of a common capacitor 14 which may if desired comprise a bipolar capacitor. An input signal from a suitable drive source such as a bipolar square waveform Y is coupled to the input conductor 16. One of the diode components 18 is switched to an energized on "on" state with each positive-going edge of the waveform Y, as indicated by waveform C in FIG. 10, and the other diode component is energized or switched to an "on" state with each negative-going edge of the waveform Y, as indicated by waveform D in FIG. 10. With light emitting diode components 18 as shown, the two opposite-polarity diode components 18 emit alternating light pulses as represented by the waveforms C and D. In one form, the diode components 18 may comprises LED's for emitting light of different color. An output voltage may also be provided by a conductor (not shown) coupled to the common conductor 20 (FIG. 9). This composite device 310 may be used, by way of example, as an analog signal storage device, or as a memory device. FIG. 11 is a schematic sectional view depicting the composite device 310 of FIG. 9 in accordance with a preferred construction. As shown, the capacitor component 14 is defined by the common conductor 20 and a second or ground conductor 24 spaced apart by an intervening layer of suitable dielectric material 22. A semiconductor layer 18 is formed on the common conductor 20. The forward-biased diode component of the composite device 310 is defined by the semiconductor layer 18 in association with an anode conductor 16a, whereas the reverse-biased diode component is defined by the semiconductor 18 in association with a cathode conductor 16b, wherein the anode and cathode conductors 16a, 16b may be both connected to the input signal on the conductor 16 (FIG. 9). The work functions of the various conductive elements are selected to provide the desired functional operation, i.e., the anode conductor 16a is formed from a material having a work function higher than the common conductor 20, which in turn has a work function higher than the cathode conductor 16b (Ae., WF 16a > WF 20 > WF 16b). In this arrangement, the work function of the common conductor 20 and the second or ground conductor 24 may be the same. However, persons skilled in the art will recognize and appreciate that a number of different work function configurations may be used, provided that the difference in work functions allows opposite polarization of the diode contacts 16a and 16b with respect to the common conductor 20. FIG. 12 depicts a circuit diagram for a stacked photovoltaic power supply 410 or the like. In this variation, a plurality of composite rectifying and charge storage devices 10 are electrically connected in stacked or series relation to form a photoresponsive system which may be used as a light- driven power supply, or as a light signal transducer. Each composite device comprises, as previously shown and described, a photovoltaic semiconductor or diode component 18 sharing a common conductor 20 with an associated capacitor 14. The opposite side of each diode component 18 is electrically coupled to the opposite or second conductor 24 of the associated capacitor 14. In addition, the common conductor 20 of the first composite device 10 is electrically coupled to the second conductor 24 of the next or adjacent device 10 in the stacked series, and the common conductor 20 of the second composite device 10 in the stacked series is similarly connected to the second conductor 24 of the next or adjacent device 10, and so on. The DC output of the composite device 410 is between a terminal 26 coupled to the common conductor 20 of the final composite device 10 in the stack, and a terminal 48 coupled to the second conductor 24 of the first composite device 10 in the stacked series. Although four composite devices 10 are illustrated in stacked array in FIG. 12, it will be recognized and understood that the stacked array may incorporate two or more such devices. The charge storage capacity, and the resultant output voltage produced by the stacked power supply, comprises a summation of the voltages stored by the multiple composite rectifying and charge storage devices.

This composite device 410 may be used either as a power supply or as a light signal transducer. Depending upon the type of charge storage element (capacitor, electrolytic capacitor, supercapacitor, storage battery, etc.), the quantity and duration of the charge storage and available output voltage will be adaptable to different uses in signal sensing, signal processing, power storage, or power generation. In addition, the device 410 may be responsive to incident continuous or pulsed light, or responsive to different angles of directions of incident light. FIG. 13 shows a further alternative preferred embodiment of the invention, wherein the composite device incorporates a photoemissive component for generating a light signal which can be detected by a photoreceptive component which is also incorporated into the composite device. More particularly, as shown, a modified composite device 510 includes a capacitor 14 defined by the common conductor 20 and the second conductor 24 with an intervening dielectric material 522 having photoreceptive characteristics as shown and described by way of example in the above-cited Japan Published Appln. JP2002152991 A2. The diode component 12 of the composite device 510 is defined by a semiconductor material 18 interposed between the common conductor 20 and an overlying conductor 16. The semiconductor 18 is formed, in the illustrative embodiment as viewed in FIG. 13, from a suitable photoemissive material. The diode conductor 16 and the second conductor 24 of the capacitor 14 are both formed from a suitable light transmissive material, as previously described herein. An insulative dielectric material 22 is interposed between the semiconductor material 18 of the diode component 12, and the photoreceptive dielectric material of the capacitor component 14, and suitable transparent protective covers layers (not shown) of glass or plastic or the like may be provided to overlie and protect the conductors 16 and 24, if desired or required. In an optimum circuit configuration, differential work functions for the diode conductor 16 and the common conductor 20 may be used for appropriate polarization of the diode component.

This combined photoemissive/photoreceptive embodiment of FIG. 13 may be used in optical scanning and/or identification systems, such as fingerprint identification systems or the like, by positioning an optically reflective surface 500 in close proximity with the photoemissive diode component 12 which has been suitable coupled with an electrical input signal for producing a light output signal indicated by arrow 501 to illuminate the surface 500. This light output signal is reflected off the surface 500, as indicated by arrow 502 to incidence upon the photoreceptive capacitor component 14 which responds thereto to produce an appropriate electrical output signal representative of characteristics of the illuminated surface 500. An external stimulus 524, for example, pressure applied by a portion of a finger surface, or light absorption of the surface, may also affect the reflectivity of the reflective surface 500, or the distance or spacing between the reflective surface and the device 510. Alternately, persons skilled in the art will recognize and appreciate that a photoemissive capacitor component as previously described herein may be employed for illuminating the surface 500, and a photoreceptive diode component as previously described herein may be used for monitoring the reflected light signal 502.

Alternately, a plurality of composite devices including at least one photoemissive component and at least one photoreceptive component may be incorporated into a matrix array or separately for illuminating the surface 500, and for monitoring light reflected from said surface 500. In the fabrication of the device 10 for use in any or all of the alternative embodiments shown and described herein, traditional polymer and organic device fabrication processes may be utilized. Polymer and organic thin films can be processed by spin-coating, ink-jet printing, roll-to-roll coating, and other coating methods. Organic thin films can also be deposited by thermal sublimation, chemical vapor deposition, and analogous methods.

Metal electrodes can be deposited on a substrate by thermal deposition under high vacuum or by the ink-jet printing process. Where conventional materials are utilized, the components of the device 10 can be assembled by the use of materials and processes well known to those skilled in the art. FIGS. 14-20 show illustrative alternative embodiments of the invention conforming to the embodiments shown and described in parent U.S. Patent 6,414,543 and in copending U.S. Publication US 2002/0140500 A1. It will be recognized and understood that the phototransducer component as described above with respect to the embodiments of FIGS. 1 - 13 may be employed in each or any of the embodiments depicted in FIGS.

14-20, for use in providing photoresponsive or photoemissive function. More particularly, the device 10 is shown in FIG. 14 is mounted on a flexible substrate 50 with all of the other components of the device 10 being the same reference numerals as the device 10 of FIG. 1. FIG. 15 is a top plan view of the device 10 of FIG. 14 and shows the device 10 superimposed on the top surface of the flexible substrate 50. The flexible substrate 50 may be manufactured from any suitable type of material. Where a flexible substrate, such as the substrate 50, is provided, it is desirable that all of the components of the device 10 be correspondingly flexible so that the device 10 may be mounted, through the flexible substrate 50, in environments where such flexibility is indicated. Typical substrates are sheets or strips of polyethylene, polyvinylchloride, or the like.

An alternative embodiment 60 of the device 10 is shown in FIG. 16 in cross section and includes elements identical with or similar to the corresponding elements of FIGS. 1 and 14-15, said elements being provided with the same reference numerals. The major difference between the device

60 of FIG. 16 and the device 10 lies in the provision of a dielectric 62 which is incorporated in a flexible substrate 64. Once again, the flexible substrate can be manufactured from strip or sheet plastic material such as polyvinylchloride, polystyrene, polyethylene, and the like. The device of FIG. 16 is shown in plan in FIG. 17. Although the flexible substrate 62 is shown as protruding beyond the limits of the remaining elements of the device 60, it is not intended that the invention be limited to that particular configuration since it is contemplated that the electronic portions of the devices may be extremely miniaturized. A further alternative embodiment 70 of the composite device 10 is shown in FIG. 18 and functions in the same manner as the devices of FIGS. 1 and 14-17. However, the various elements of the embodiment 70 are disposed in planar rather than a superimposed relationship which is characteristic of the previously discussed embodiments. The planar relationship of the various components minimizes the parasitic capacitance of the diode and also provides for various advantages in device fabrication. The device 70 incorporates a conductive layer 71 having a low work function and terminating to create a gap 72. The conductive layer 71 forms the anode terminal 73 of the rectifying diode 74. A common conductive layer 76 having a high work function and larger surface area than the first conductive layer 71 is provided at the gap 72 and constitutes the cathode of the diode 74 as well as the top layer 78 of the capacitor 80. A dielectric substrate 90 is provided below the conductors 71 and 76 and an organic molecular semiconductor 110 is provided across the gap and permits the performance of the rectifier function of the device 70. A conductive layer 112 underlies the dielectric substrate 90 and the completion of the capacitor 70 is accomplished. An AC circuit 120 is connected at one side to the conductive layer 71 and at the opposite side to the layer 112 which acts as the ground of the circuit. The DC output is located at 114 on the layer 76.

The planar structure of the device 70 (FIG. 18) permits the formation of a composite device of opposite polarity by using opposite combinations of high and low work function conductors such as the layers 71 and 76. In particular, by reversing the work functions of the conductive layers 71 and 76, so that the conductive layer 71 has a high work function and the conductive layer 76 has a low work function, the DC output at terminal 114 will be reversed in polarity, namely, V- instead of V+. Such arrangement of the conductive components with higher and lower work function thus effectively reverses the polarity of the diode component in the circuit, as depicted by way of example in FIGS. 2 and 3, and may be employed in any of the herein-described embodiments of the invention. An alternative planar device 220 is shown in FIG. 19 as including the layers 71 and 76 of the device 70 of FIG. 18. However, instead of incorporating the flexible dielectric 110 of the device 70, a common layer 122 is provided which serves as a semiconductor connection to the common layer 76 and as a dielectric between the common layer 76 and the layer 126 of a capacitor 127. Therefore, in this embodiment, there are two elements of the device 220 serving a common function, namely, the semiconductor/dielectric layer 122 and the common conductive layer 76. The layer 126 is a high work function layer and serves as the ground for the circuit of the device 120. The provision of the coplanar layers 71 and 76 and the common performance of the layer 76 and the layer 122 greatly simplify the fabrication of the device 120 on the flexible substrate. There is an air gap

200 or other insulating layer between the poly-semiconductor 122 and the flexible substrate 128. This air gap 200 is adjacent to the layer 126. I a power supply configuration as shown, the AC input 132 is connected on one side to the anode layer 71 and on the other side to the common conductor layer 76 with the DC output being connected to the layer 76 at 134.

An alternative embodiment 140 of the device is shown in FIG. 20 of the drawings as including an AC input at 142 which is connected to an anode 144. The anode 144 communicates with one side 146 of an interdigitate capacitor unit 150. The interdigitate capacitor layers or fingers 152 of said one side fit between corresponding layers or fingers 154 of the other side 156. The entire assemblage is encapsulated or overlaid by semiconductor/dielectric material 158 to create the rectification and capacitance effects. The device 150 is particularly suited to deposition on a flexible substrate and is susceptible to various well-established methods of deposition conductors such as conductive inks, organic polymers, or the like.

In each of these alternative configurations for the composite rectifying charge storage device, the phototransducer component responds to an incident radiant energy such as light to switch to or vary a photoconductive or photovoltaic state, or alternately responds to an electrical signal to produce a corresponding emitted light signal.

A variety of further modifications and improvements in and to the rectifying charge storage device of the present invention will be apparent to persons skilled in the art.

Claims

What is Claimed is:

1. A rectifying charge storage device, comprising: a rectifier structure fabricated with a common conductor forming a side of the rectifier structure; and a capacitor structure fabricated as a single unitary structure with the rectifier structure such that the capacitor structure incorporates the common conductor of the rectifier structure as a side of the capacitor structure, the capacitor structure to receive the rectified current from the rectifier structure over the common conductor; at least one of said rectifier structure and said capacitor structure incorporating at least one phototransducer for converting between light and electrical signals.

2. The rectifying charge storage device of claim 1 , wherein said phototransducer is incorporated into said rectifier structure.

3. The rectifying charge storage device of claim 1 , wherein said phototransducer is incorporated into said capacitor structure.

4. The rectifying charge storage device of claim 1 , wherein said at least one phototransducer comprises a first phototransducer incorporated into said rectifier structure and a second phototransducer incorporated into said capacitor structure.

5. The rectifying charge storage device of claim 1 , wherein said phototransducer comprises a photoreceptive component for producing an electrical signal in response to an incident light signal.

6. The rectifying charge storage device of claim 5, wherein said rectifier structure includes at least one diode incorporating said photoreceptive component.

7. The rectifying charge storage device of claim 6, wherein said at least one diode comprises a photovoltaic diode.

8. The rectifying charge storage device of claim 6, wherein said at least one diode comprises a photoconductive diode.

9. The rectifying charge storage device of claim 5, wherein said capacitor structure includes a capacitor incorporating said photoreceptive component.

10. The rectifying charge storage device of claim 1 , wherein said phototransducer comprises a photoemissive component for producing a light signal in response to an electrical input signal.

11. The rectifying charge storage device of claim 10, wherein said rectifier structure includes at least one diode incorporating said photoemissive component.

12. The rectifying charge storage device of claim 11 wherein said at least one diode comprises an LED.

13. The rectifying charge storage device of claim 10, wherein said capacitor structure includes a capacitor incorporating said photoemissive component.

14. The rectifying charge storage device of claim 13, wherein said capacitor comprises said common conductor, a second conductor, and a dielectric material disposed therebetween, said dielectric material including an electroluminescent material.

15. The rectifying charge storage device of claim 1 , wherein said at least one phototransducer comprises a photoemissive component and a photoreceptive component.

16. The rectifying charge storage device of claim 15, wherein said photoreceptive component is positioned on or within the device for receiving light produced by said photoemissive component.

17. The rectifying charge storage device of claim 15, wherein said photoemissive component is incorporated into one of said rectifier and capacitor structures, and said photoreceptive component is incorporated into the other of said rectifier and capacitor structures.

18. The rectifying charge storage device of claim 15, wherein said photoemissive and photoreceptive components are both incorporated into said rectifier structure.

19. The rectifying charge storage device of claim 15, wherein said rectifier structure includes a first diode incorporating said photoemissive component, and a second diode incorporating said photoreceptive component.

20. The rectifying charge storage device of claim 10, wherein said electrical input signal comprises an AC signal.

21. The rectifying charge storage device of claim 10, wherein said electrical input signal comprises an inductive signal.

22. The rectifying charge storage device of claim 10, wherein said electrical input signal comprises an electromagnetic signal.

23. The rectifying charge storage device of claim 10, wherein said electrical input signal comprises a signal representative of a monitored environmental parameter.

24. The rectifying charge storage device of claim 5, wherein said incident light signal comprises a modulated light signal.

25. The rectifying charge storage device of claim 1 , wherein said rectifier and capacitor structures are carried on a common substrate.

26. The rectifying charge storage device of claim 25, wherein said common substrate is a flexible substrate.

27. The rectifying charge storage device of claim 25, wherein said capacitor structure incorporates said common substrate.

28. The rectifying charge storage device of claim 27, wherein said capacitor structure comprises said common conductor, a second conductor, and a dielectric material therebetween, said substrate being incorporated into said dielectric material.

29. A rectifying charge storage device, comprising: a rectifier; a common conductor connected to one side of said rectifier; a capacitor incorporating said common conductor; said rectifier, common conductor and capacitor comprising a unitary element; and at least one phototransducer for converting between light and electrical signals.

30. The rectifying charge storage device of claim 29, wherein said phototransducer is incorporated into said rectifier.

31. The rectifying charge storage device of claim 29, wherein said phototransducer is incorporated into said capacitor.

32. The rectifying charge storage device of claim 29, wherein said at least one phototransducer comprises a first phototransducer incorporated into said rectifier and a second phototransducer incorporated into said capacitor.

33. The rectifying charge storage device of claim 29, wherein said phototransducer comprises a photoreceptive component for producing an electrical signal in response to an incident light signal.

34. The rectifying charge storage device of claim 33, wherein said rectifier includes at least one diode incorporating said photoreceptive component.

35. The rectifying charge storage device of claim 34, wherein said at least one diode comprises a photovoltaic diode.

36. The rectifying charge storage device of claim 34, wherein said at least one diode comprises a photoconductive diode.

37. The rectifying charge storage device of claim 33, wherein said capacitor incorporates said photoreceptive component.

38. The rectifying charge storage device of claim 29, wherein said phototransducercomprises a photoemissive componentforproducing a light signal in response to an electrical input signal.

39. The rectifying charge storage device of claim 38, wherein said rectifier includes at least one diode incorporating said photoemissive component.

40. The rectifying charge storage device of claim 39, wherein said at least one diode comprises an LED.

41. The rectifying charge storage device of claim 38, wherein said capacitor incorporates said photoemissive component.

42. The rectifying charge storage device of claim 41 , wherein said capacitor comprises said common conductor, a second conductor, and a dielectric material disposed therebetween, said dielectric material including an electroluminescent material.

43. The rectifying charge storage device of claim 29, wherein said at least one phototransducer comprises a photoemissive component and a photoreceptive component.

44. The rectifying charge storage device of claim 43, wherein said photoreceptive component is positioned on or within the device for receiving light produced by said photoemissive component.

45. The rectifying charge storage device of claim 44, wherein said photoemissive component is incorporated into one of said rectifier and said capacitor, and said photoreceptive component is incorporated into the other of said rectifier and said capacitor.

46. The rectifying charge storage device of claim 44, wherein said photoemissive and photoreceptive components are both incorporated into said rectifier.

47. The rectifying charge storage device of claim 44, wherein said rectifier includes a first diode incorporating said photoemissive component, and a second diode incorporating said photoreceptive component.

48. The rectifying charge storage device of claim 38, wherein said electrical input signal comprises an AC signal.

49. The rectifying charge storage device of claim 38, wherein said electrical input signal comprises an inductive signal.

50. The rectifying charge storage device of claim 38, wherein said electrical input signal comprises an electromagnetic signal.

51. The rectifying charge storage device of claim 38, wherein said electrical input signal comprises a signal representative of a monitored environmental parameter.

52. The rectifying charge storage device of claim 33, wherein said incident light signal comprises a modulated light signal.

53. The rectifying charge storage device of claim 29, wherein said rectifier and said capacitor are carried on a common substrate.

54. The rectifying charge storage device of claim 53, wherein said common substrate is a flexible substrate.

55. The rectifying charge storage device of claim 53, wherein said capacitor incorporates said common substrate.

56. The rectifying charge storage device of claim 55, wherein said capacitor comprises said common conductor, a second conductor, and a dielectric material therebetween, said substrate being incorporated into said dielectric material.

57. An optical scanning and identification system, comprising: a rectifier; a common conductor connected to one side of said rectifier; a capacitor incorporating said common conductor; said rectifier, common conductor and capacitor comprising a unitary element; first phototransducer means including a photoemissive component for producing a light output signal for incidence upon an object to be identified; and second phototransducer means including a photoreceptive component receiving and responding to light reflected from the object to be identified, for producing an electrical output signal.

58. The optical scanning and identification system of claim 57, wherein said rectifier incorporates at least one of said photoemissive and photoreceptive components.

59. The optical scanning and identification system of claim 57, wherein said rectifier incorporates both of said photoemissive and photoreceptive components.