GB2613221A - Displays of integrated solar chargeable functionalities with retained architecture and visibility - Google Patents

Abstract

A device comprising a solar cell 300 and a display 100 comprising a light-emitting layer, a transistor array, and a reflective sheet 200, wherein the reflective sheet reflects visible light 520 and transmits near-infrared light 600, and the solar cell is arranged behind the display. The reflective sheet may comprise dielectric mirrors, distributed Bragg reflectors, reflectors having alternating layers or reflectors gradients of different refractive indices. The solar cell may comprise of one of: amorphous silicon (a-Si), crystalline silicon (c-Si), monocrystalline silicon (mono-Si), polycrystalline silicon (multi-Si); copper indium gallium selenide (CI(G)S); organic (OPV); or quantum dot. The display, reflective sheet, or solar cell may be directly deposited thereon in order to create a monolithic display / solar-cell unit. The display may be an LCD or LED type.

Description

Displays of integrated solar chargeable functionalities with retained architecture and visibility

FIELD OF THE INVENTION

[0001] The present invention relates to the integration of solar cells into the displays of electronic devices as smartphones and portable electronics.

BACKGROUND OF THE INVENTION

[0002] The operation time of mobile electronic devices is limited by the power source energy capacity and the device's power consumption. In recent decades, a leviathan increase in electronic device performances was accompanied by a moderate increase in battery capacity. Limited weight and volume hinder the capacity growth of similar type batteries. The addition of solar cells on the exterior surface of the devices can add to the mobility of the devices by renewable charging with solar energy. Nonetheless, major disadvantages render this solution not desirable in most cases. This is due to the weight addition, volume consumption, surface area allocation, change of device architecture, and glass breakage issues.

[0003] Solar charging of smartphones, tablets, digital cameras, satellite navigation devices, and many more display-containing devices carries unique, indispensable advantages. The full charging of small-capacity batteries with relatively large solar panels is feasible. Charging relatively high-capacity batteries by small-sized solar cells may function as a complementary charging feature for the average user. Nevertheless, many of the benefits are preserved, even for relatively small screen devices, especially at times when extra charging is required without an electrical grid or charger.

SUMMARY OF THE INVENTION

[0004] In order to overcome many of the drawbacks mentioned above while achieving efficient solar charging, the current invention discloses a new technology to integrate photovoltaics into the displays of electronic devices. The illumination of the solar apparatus through the display will resolve many of the disadvantages of external solar panels, as ones that are positioned on the back of the device. Besides the unnecessary allocation of the device's surface area and lack of external glass breakage risk, this invention will allow minimal addition of components to the device. It will also minimize the weight addition, volume consumption, manufacturing costs, and retention of the design and appearance [0005] The challenge of integrating solar cells into displays lies in the photovoltaic panels' design, usually aimed to absorb most visible light. By contrast, displays are naturally designed to emit bright and colorful light. Many displays of mobile electronic devices contain light sources -typically LED lights and a reflective sheet. The reflective sheet is any reflective surface or reflective plate as an aluminium layer. This mechanism increases the display's efficiency by reflecting the fraction of light emitted towards the back of the device. Consequently, more light is now directed to the desired front surface of the display without additional power input.

[0006] Recently, displays that allow the light to go through their backside, and hold transparency characteristics, were devised for applications as store advertisements. These displays are also referred to as see-through displays and lack such inner light reflectance qualities. It follows from their primary objective to transmit light through, and therefore are usually less bright. Alternatively, to reach the same brightness as a non-transparent display, the power sources must generate much more light. A part of this light is pointed in the wrong direction -backward, and accordingly, this mode consumes significantly more power and may even double the display's power consumption.

[0007] Searching for a viable display with photovoltaic capabilities, see-through displays were utilized (as in patent No. CN212029377U). The straightforward installation of solar panels behind such a transparent display should, indeed, allow most of the solar panel operation This combination, however, as a solar chargeable solution for a non-transparent display is not a promising one. The reason for that is the fact that in most mobile electronic devices, the power consumption of the display, out of the total power consumption, is considerable. This display power intake is also comparable to the maximal power output from a similar-sized solar cell. Therefore, this combination will consume more power by the display during regular usage, and not elongate the utmost usage time of the device in most cases. It should be noted, additionally, that the absorption of light emitted from the display itself, by solar cells may only reach an energy conversion of about 20%. Together with the energy losses from the power to light conversion of the display, the total energy recycling process should be small. Some more prior art publications as in patents No. US2009/219273, CN2020762701J, US20090103161A1, and JP2014115526A position solar panels behind transparent displays. A semitransparent reflective sheet of a certain percentage of visible light does not overcome the fundamental hurdle. It is comparable to a screen with one part of the above solution and the other with a non-transparent aluminum reflective sheet. Furthermore, patent No. US8194197B2 utilizes numerous pixel-sized solar panels in front of each pixel electronics.

[00081 To construct a combination of an efficient and economically viable display with photovoltaic functionality of the same properties, the following features are desired: keeping the display technology and visibility substantially unmodified; maintaining an efficient power consumption for the display module; enabling the integration of efficient and proven photovoltaic technologies; adding minimal volume and weight of the composed solar display as well as maintaining the shape of the display; and preferably, not diverging significantly from its internal structure and general manufacturing procedures.

[0009] It is an object of the current invention to integrate solar cells into the display of mobile electronic devices. For this reason, it is important to consider the electromagnetic light absorbed by the human eyes. Human color vision is trichromatic. Cone cells in the retina contain opsin proteins with photopigments as 11-eis-hydroretinal. Absorbed visible light triggers signals from those cells to the brain's visual cortex, which translates, in turn, the signals into an image. The cones are classified according to their peak absorbance as short (S), medium (NI), and long (L) types. The peak absorbance of the L cones is in the range between 564 nm to 580 nm -in the yellow-orange region. This absorbance decreases sharply towards higher wavelengths, with little absorbance above 700 nm. Displays are generally designed to emit light according to human vision, with three spectral crests. The longest wavelength of which is in proximity to the L cone absorbance. This crest is located in many displays just below 600 nm. Organic light-emitting diode (OLED) displays may exceed this wavelength slightly to around 620 nm. Steeply declining with the wavelength, the red light of these displays emitted at 700 nm is negligible. In this declining region, both the light intensity and the human brightness sensitivity falls. Together, a synergetic effect is formed. It renders the emitted light rapidly less perceptive with the wavelength increase at that region.

100101 It is a core object of the current invention to disclose mobile electronic devices with photovoltaic display properties that primarily utilize light with a higher wavelength than about the peak of the human eye L cones absorbance. In order to allow this light to penetrate through the display, it includes a reflective sheet that is substantially transparent to these wavelengths. Nonetheless, according to the current invention, the reflective sheet will preserve its power-conserving functionality by reflecting most light in the eye-sensitive wavelengths. This invention, therefore, primarily differs from the specified prior art by allowing both efficient, screen-integrated solar power supply and efficient display operation.

100111 Rarely pure materials exhibit comparable attributes for the desired reflective sheet. Such reflective properties can be reached, though, by dielectric mirrors or distributed Bragg reflectors. Dielectric mirrors, also known as Bragg mirrors, can be designed to reflect light efficiently in a certain range of wavelengths and transmit light on another. Alternating deposition of high and low refractive-index dielectric material layers, like TiO2 and MgF2, can form such mirrors. Formulas for the design of reflectance and transmittance regions are well established (as developed initially by P. Baumeister"/ Opt Soc. Am. 48, 955-958, 1958, and computer models as S. Larouche and L. Martinu, Applied optics 47, 219-230, 2008). These take into account parameters as the thickness of each of the alternating layers, their dielectric properties, and the number of the layers.

[0012] A cold mirror is a dielectric mirror that reflects most visible light while efficiently transmitting higher wavelength beams. For instance, certain cold mirrors made of TiO,/MgF, or Ti02/Si02 can meet the reflective sheet criteria of the current invention. Typically, dielectric mirrors are fabricated by intermittent thin layers deposition on top of a rigid substrate like glass. In some cases, as specified below, such dielectric mirrors may be deposited directly on other display layers as a substrate instead of a glass. Moreover, functional layers of a solar cell may be directly deposited on top of the mirror, according to this invention. In these cases, the relative permittivity of the adjacent layers should be included in the mirror design calculation for accurate projection. Also, one or more buffer layers, as ones of low refractive index, next to the mirror may be added to achieve the desired reflectance pattern. The angle of incidence should also be considered in all cases. Dielectric mirrors reflectance threshold typically shifts towards lower wavelengths with incident angle increase. Devising a safety margin of high reflectance towards higher wavelengths will maintain all colors pronounced from wider viewing angles.

[0013] The current invention's scope includes, yet is not limited to, the following mobile electronic devices that include a photovoltaic display: smartphones; tablets; laptop computers; electronic watches; digital cameras; e-readers; cellular phones; smartwatches; and satellite navigation devices. Moreover, solar displays, according to the current invention, can be a part of stationary positioned displays. These include information and commercial display signs, electronic traffic signs, dynamic message signs, and more. Indoor devices are also included; these may be charged mainly by artificial lightings, such an infra-red lasers. Some of the display technologies which can be utilized for the display function are of the following types: OLED, including QD-OLED; active-matrix °LED (AMOLED); quantum nanorod emitting diode, polymer light-emitting diode (PLED); electroluminescent quantum dots displays (EL-QLED); micro-LED; QLED (photo-emissive quantum dot display); all Liquid crystal display (LCD) technologies, including Edge-lit LCDs and backlit LCDs. They may also be formed in inverted configurations. According to the current invention, the displays can include the feature of a touch screen, such as a resistive touch screen, or a multi-touch, like a capacitive touch screen. Flexible displays and flexible mobile electronic devices are also included in the scope of this invention For example, these could be displays of foldable smartphones and flexible wearable devices [0014] According to the current invention, the reflective sheet of the display should act similarly to a cold mirror. Most display technologies require reflective surfaces on the back of the display in order to redirect light to the front. Edge-lit LCDs for instance are liquid crystal displays that include a light guide plate (LGP) and light sources as LEDs on their edges. The light goes through the LGP, which is made of a transparent substance as PMMA. Its purpose is to redirect the light from the edge light sources to the surface of the display in about a homogeneous manner. Some of the light, emitted to the opposite side of the display surface, is reflected back to the LGP by a reflective surface, also called a reflective sheet. Backlit LCDs, on the other hand, use light sources on the back of the LCD. A more significant part of the light may then be illuminated to the back of the display in this manner. That light is commonly reflected back to the display by a reflective sheet positioned behind the light-emitting substance.

[0015] Increasingly popular among mobile devices, OLED displays, including AMOLED ones, produce light from LEDs on each pixel. These displays include a transparent cathode layer, an active organic layer, a thin film transistors array, and an anode. That anode on the back of each pixel is usually made from a thin layer of low work-function metal as calcium or barium and a thicker aluminium layer. The latter acts as a conductive, rigid substrate which reflects light emitted from the organic layer to the front of the display. One purpose of this aluminium layer, as mentioned, is to prevent a waste of light emitted to the back of the display instead of its front. Clearly, this light does not have to be perpendicular to the surface but includes any projection which deviates from the display surface backward. OLED-related technologies contain different electroluminescent materials instead of the organic layer and have a reflective sheet as well. PLED, also known as P-OLED, utilizes electroluminescent conductive polymers as polyfluorene. In EL-QLED, light is emitted directly from a quantum dots layer by radiative recombination of electrons and holes. Furthermore, micro-LED displays include microscopic LEDs in order to form each pixel. Recently developed, QDOLED displays produce low-wavelength light in a similar manner to OLED. This light passes through photoluminescent quantum dots to create a vibrant, colorful picture. Quantum nanorod emitting diode is a closely related technology to QDOLED. In this technology, quantum nanorods replace the organic emitting layer with an electroluminescent nanorod film. Emitted low wavelength radiation then passes through photoluminescent quantum dots layers to produce the desired hue.

100161 The current invention scope includes displays and mobile electronic devices, with display technologies including all the ones mentioned above. These should hold additional high-wavelength transmittance attribute of the display's reflective sheet. This kind of reflective sheet, which can be referred to as a cold mirror, should reflect most of the visible light of low wavelengths. On the contrary, high wavelength visible light, as high wavelength red and near infra-red light, should be mostly transmitted. Such cold mirror can be a dielectric minor. Finally, one or more solar cells will face the back of the cold mirror to absorb the transmitted light, according to the current invention. These solar cells will generate electric energy from high wavelength photons, for the charging the batteries of the devices during illumination. Considering the following technologies: OLED (including AMOLED and QD-OLED and other OLED related technologies); PLED; EL-QLED; quantum nanorod emitting diode; and micro-LED, typically the back electrode acts also as a reflective sheet. And since dielectric mirrors are not conductive, in order to achieve conductivity, another considerably transparent and conductive layer is required. This can be, yet is not limited to, made of one or a combination of the following materials: conductive metal oxides as indium tin oxide (ITO), fluorine tin oxide (FTO), BaSn03, and doped zinc oxide as aluminium doped ZnO (AZO); conductive carbon allotropes as graphene and carbon nanotubes; conductive polymers as poly(3,4-ethylenedioxythiophene) (PEDOT) and a blend of PEDOT with poly(styrene sulfonate) (PEDOT:PSS), polyaniline, polypyrrole, polythiophene. Also, a conductive ultra-thin metal conductive film can serve as a semitransparent or transparent conductive film (TCF) electrode. This may be a nanometer-scale, semitransparent low work-function metal, as calcium and barium. Such ultra-thin metal layer or only a doping or clusters of the metal may be applied over a substantially transparent electrode for electrode surface optimization. Alternatively, to facilitate electron injection, additional materials as 4,7-dipheny1-1,10-phenanthroline (Bphen) in addition to Cs2CO3 can be employed over the transparent cathode as ITO.

100171 Included as a transparent layer in the current disclosure, ITO is an abundant material among displays and possesses minimal absorbance throughout the visible spectrum. ITO is typically fabricated by a highly energetic sputtering process. Sputtering over other, relatively sensitive layers of the display to fabricate an ITO electrode might be damaging for those layers. Therefore a buffer layer can be employed in between. It can be made, for example, of metal oxides as W03, Re03, Mo03, or NiO. The same principle is true for other sputtered films and sputtering of ITO on top of other solar cell layers. A transparent thin-film transistors array (TTFT), instead of a regular TFT array, is an optional feature for the display. It will allow the area covered by transistors to be transparent. To achieve transparency, conductive and semiconductor metal oxides as ITO, AZO, and zinc tin oxide (ZTO) are widely used for the gate, channel, drain, and source materials.

100181 The power extraction of such solar displays depends on a few factors. At first, the input energy flux depends on the transmitted wavelengths through the dielectric mirror and other display layers. Two energy bands characterize standard one-junction solar cells. The band gap between the lowest unoccupied molecular orbital and the highest occupied molecular orbital defines the minimal photon energy absorbance of the cell. Also, photons with higher energy than the band gap, can excite electrons to the conduction band, with the excess of their energy dissipating as heat. The solar cells will be able to absorb light in a range between their maximal wavelength absorption and the minimal wavelength transparency of the cold mirror.

100191 Interestingly, a solar cell with maximal absorbance of 1100 nm, positioned behind a 650 nm threshold cold mirror, can be excited by most of the solar flux. Indeed, integration of the solar power flux over the range of 650 nm and 1100 nm, according to A1\41.56 solar spectrum standard, results in ca. 526 W/m2. Integration from a higher wavelength of 700 nm to 1100 nm brings about as much as 386 W/m2. Finally, the solar cell(s) converts a part the solar energy flux into electric power. Usually, the main limiting factor of photovoltaic efficiency is the energetic difference of the various photons over the solar spectrum.

Depending on the frequency, photon energy is inversely proportional to the wavelength. Energy in excess of the band gap of the solar cell dissipates to heat and limits the possible efficiency of the cell. For instance, silicon-based solar cells are characterized by a 1.1 eV band gap, equivalent to 1127 nm light. A 400 nm photon, on the other hand has an energy of ca. 3.1 eV. Higher wavelength photons are closer to the silicon band gap in energy. Therefore, contributing a higher percentage of their energy to electric energy and less to heat dissipation. A 650 nm photon energy is about 1.91 eV, and 1.77 eV is equivalent to a 700 nm photon. Consequently, by the current invention, a relatively narrow range of wavelengths, in proximity to the band gap will allow substantially higher average efficiency. Conventional silicon-based solar cells are known to reach about 90% of external quantum efficiency in the range of 650 nm to 1000 nm. That efficiency falls to roughly 20% in 1100 nm in nearly a linear fashion. Considering a silicon-based solar cell behind a dielectric mirror that transmits light with 90% efficiency over 650 nm, with a power conversion efficiency of 50% in the 650 nm -1100 nm range. A production of ca. 237 Wim= under frill sun conditions will then be reached. These results are equivalent to 1.18 W charging for a 50 cm' display smartphone or ca. 10.6W for a 450 cm2 display tablet.

[0020] Novel technologies of yet higher efficiency solar cells might be considered not economical for large-scale employment for electricity production purposes. These technologies may be of exceedingly economic use, though, in the displays of portable devices. Noteworthy, the band gap of the solar cells by this invention can range from visible to infra-red photon energy. In the case of a relatively high minimal transmittable wavelength of the display, the preferable band gap may be extended farther towards the infra-red range. UV light is usually filtered before reaching photovoltaics to avoid component degradation. Yet, if allowed through the display, the reflective sheet may also be tuned to allow at least partially the transmittance of UV light and contribute to the operation of the solar cell(s). Combination with additional UV absorbing panels on the front, or solar cells to the sides, of the display (as in patent app. US20210104908A1 and US20210103171A1) is an optional feature as well. According to the current invention, all photovoltaic mechanisms may be set to operate during device operation.

[0021] Additionally, the displays and electronic devices included in the scope of the current invention can be exposed to any artificial light. For example, this can be light containing red or near infra-red radiation by LED light or a laser beam. An optional feature of the current invention is one or more additional reflectors to the device or the modification of a small part of the reflective sheet of the display. These will retrieve an external electromagnetic signal to localize the device and help direct an artificial light beam on the display of the device. This or another tracing method can allow wireless charging with a relatively large cross-sectional area beam to hit any part of the screen. The beam's relatively small power-to-area is an embodiment that is important for safety reasons, such as fire safety and eye protection.

[0022] The flux of high wavelength solar radiation passing across the display up to the photovoltaics is a key factor of the electric output. Most display constituents can be fabricated to be virtually transparent. Some layers as the front substrate and front conductive layers are regularly clear, and some are specifically fabricated for this purpose, as in see-through displays. Nevertheless, color filters and polarizers, which are abundant in LCD displays, still absorb a part of the light. A linear polarizer should ideally absorb half of passing unpolarized light. Aligning the polarization between either crossed or parallel pairs of polarizers by a liquid crystal layer should allow passing light to go through the second polarizer unintermpted. The first polarizer, however, will reduce unpolarized incident light by about a half. Color filter-containing displays can have significant absorption of high wavelengths as well. These shall hinder the light-to-current efficiency of a successive photovoltaic apparatus. Infra-red transparent materials for the color filter films should rise this efficiency back. Evidently, LCD see-through panels can still allow the optical properties for partial transparency. Fortunately, LED see-through displays lack much of the mentioned optical hurdles. These displays utilize see-through cathodes to reach remarkable transparency. As a result, display technologies such as OLED inorganic LEDs, PLED, quantum nanorod emitting diodes, and related technologies are all preferable for implementing the current invention.

[0023] Several solar cell technologies can be applied in the construction of solar chargeable electronic devices and photovoltaic displays according to the current invention. These include, but are not limited to, the following solar cell types: silicon-based solar cells, including amorphous silicon solar cells (a-Si), crystalline silicon solar cells (c-Si), monocrystalline solar cells (mono-Si), and polycrystalline solar cells (multi-Si); copper indium gallium selenide solar cells (CI(G)S -meaning to include CIGS and CIS); organic solar cells (organic photovoltaics, OPV); and quantum dot solar cells. Silicon solar cells are notable for high stability, efficiency, and band gap in the infra-red region, which is a preferable feature for the current invention. They allow more light to be utilized in the range between the reflector and the thresholds of the solar cells, up to ca,] 100 nm. OPV, for example, allows convenient application as thin films on top of the reflector -using it as a rigid substrate. The absence of an additional macroscopic glass scaffold allows weight changes and volume consumption of the added solar panels to be negligible.

[0024] A further means of charging mechanism may be applied to adjust the voltage output of the solar cell(s) to the charging voltage of the batteries. This charging mechanism can be a part of the electric grid charging system of the device or directly communicate the solar cell(s) to the batteries. The charging mechanism may contain power optimizers for the solar cells and DC to DC converter as a Dickson multiplier. It can increase the low voltage output of a solar cell to the charging voltage. Additionally, the produced electricity may be partly utilized directly by the device without charging the batteries first. Not restricted to one type of solar cell, the scope of the current invention includes a combination of types in the same device and includes the usage of tandem, Two-junction, and other multijunction photovoltaics.

[0025] According to this invention, a reflective sheet such as a dielectric minor with the specified attributes replaces the traditional display's reflective sheet as an aluminium reflective sheet. One or more solar cells cover at least a part of the area beyond the reflective sheet, facing about the back of the display. The solar cell(s) can be manufactured separately and installed about parallelly to the display, with or without any layer as adhesive, resin, or buffer in between. Alternatively, solar cell(s) can be directly fabricated on top of the reflective sheet surface. Also, the reflective sheet itself can be fabricated directly over the back surface of the display or manufactured separately, with or without the solar cell(s). If manufactured independently, the reflective sheet can then be installed adjacent to the other display films with or without any additional connecting layer. For example, a dielectric mirror can be fabricated directly on top of a LOP. Later, a separately built c-Si solar cell is installed adjacently to the mirror. Alternatively, an OPV solar cell can be directly fabricated on top of this dielectric mirror. Moreover, the fabrication of all of these components directly on top of each other is a preferable embodiment. This structure will allow the reflective sheet and solar cell(s) to be fabricated correspondingly as thin layers on top of the display. Nevertheless, each one of the three components, namely: all display components without the reflective sheet; reflective sheet with the high wavelength transmittance attribute; and solar cell(s) -can be manufactured separately, or with one of its neighbors as a pair, and installed next to the other layers.

[0026] The fabrication of thin layers of the dielectric mirror and the solar cell(s) can be performed by several methods. These include but are not limited to: chemical deposition methods as CVD (chemical vapor deposition), ALD (atomic layer deposition), physical deposition methods as molecular beam epitaxy, pulsed laser deposition, and evaporation methods; and also sputtering techniques. Important virtues can rise from the direct fabrication of thin films of the mirror or solar cell(s) on top of the rigid substrate of the display. Independent solar cells and mirrors usually include a glass substrate. This millimeters-thick glass substrate is the largest solar cell or mirror component in terms of volume and weight. It provides a rigid and transparent substrate to support the thin layers mechanically. Fabrication of OPV solar cell, for example, on top of a rigid dielectric mirror, renders additional rigid glass substrate for the solar cell unnecessary.

[0027] An optional feature of the current invention is a compensation mechanism to a possible partial red or other color brightness decrease. Display color changes should be imperceptible in most cases for the reasons described earlier. Yet, choosing a reflective sheet permeable to relatively low wavelength radiation may result in a slightly noticeable change. A calibration mechanism may be applied to fully or partially compensate for any color changes which may result from the modified reflectance spectrum of the new reflective sheet. This can be, for example, in the form of display software adjustment, calibrated to brighten mostly the red emission when the display should express colors of high wavelengths. It may also be in the form of a hardware change that allows higher red light source operation. Such adjustment can be significant mainly to the expression of colors near the threshold of reflectance by the reflective sheet.

[0028] In addition to the main uses and features of the current invention, two corollaries rise in the form of heat dissipation and green energy production. Photovoltaic cells are capable of partially transforming red and near infra-red light to electrical power. As a consequence, this light energy to not convert into heat. It is desirable, especially when the screen is exposed to sunlight. Green energy production is desirable as well. Extensive production of green and renewable energy among mobile and other electronic devices at a global scale is expected to reduce carbon emissions and have a small moderating effect on climate change.

[0029] The following specific examples will shed further light on the invention and its implementation methods. These examples are not intended to limit the scope of the invention by any means. More functional display and solar cell layers and components could be utilized in production than the basic ones mentioned here as an example.

[0030] The first example is a smartphone with solar charging capabilities. This smartphone is comprising an OLED display which covers almost entirely all of its front side. Said display contains a cold mirror which is a dielectric mirror, instead of the commonly used aluminium reflective sheet. Fabricated on the backside of the mirror is an OPV solar cell. More specifically, an OLED display comprising a capacitive multi-touch screen rigid scaffold. This substrate is covered with a TTFT array and typical OLED functional layers These include ITO anodes which are electrically connected to the TTFT for each sub-pixel; a hole injection layer (NIL); a hole transport layer (HTL); an organic emissive layer; a blocking layer (BL); an electron transport layer (ETL): a buffer layer (W03, 60 nm), and an ITO cathode -fabricated by a sputtering process over the buffer layer. On top of this cathode, a buffer layer is deposited, followed by an alternating array of Ti02/MgF2 layers, directly deposited to form a dielectric mirror. This mirror is a cold mirror with a threshold of about 680 nm. Additional ITO layer is directly deposited on top of said dielectric mirror to form an anode to an OPV. It is followed by the deposition of an HTL layer, a donor layer (made of P3HT), an acceptor layer (made of ICBA), and an ETL layer. Aluminium is then vaporized on top of the buffer layer to form the cathode to the solar cell. Said OPV electrodes are wired to a Dickson multiplier as a charging mechanism, which can charge the batteries of said smartphone. Exposing this smartphone to the sunlight will allow high wavelength radiation to go through the display's OLED and dielectric mirror parts. Absorption in the OPV would then generate electricity for the smartphone.

100311 The second example is of a non-monolithic smartphone with solar capabilities.

This smartphone includes a PLED display with a touch screen and the functional components of TTFT array, ITO anode, HIL, HTL, polymeric emissive layer, BL, ETL, and a buffer layer. On top, an AZO conductive transparent layer serves as the cathode for the display. Over this cathode, ten pairs of Ti02/Si02 layers are directly deposited. This pattern acts as a dielectric cold mirror with a threshold around 700 nm. Separately made, a monomystalline silicon photovoltaic panel is installed immediately behind said dielectric mirror. This high-efficiency panel is electrically connected to a charging mechanism of the batteries of the device. The high efficiency of the mono-Si solar panel is harnessed for energy extraction from natural or artificial light over 700 nm and below the ca.1100 nm panel threshold. This solar cell could be replaced by a plurality of smaller ones. For example, if this smartphone was a foldable one, two or more mono-Si solar panels could be installed instead of one. Foldable solar panels of different technologies which allow flexibility as OPV are another option. In the case of a rigid device, the silicon solar cell here is embedded inside the mobile device and, moreover, can be fixed to the display. Therefore, the substrate of the silicon solar cell can be kept to a minimum of thickness, weight, and volume. Four small retroreflectors are embedded in the glass of said solar cell, next to its corners. These are covered with an infra-red only reflecting dielectric mirror. Together they allow the display localization by an infra-red signal for the illumination by artificial light.

[0032" The third example is of a solar e-reader. This device contains an edge-lit LED display. It includes the typical functional layers of the display as a touch screen, color filter for the different pixels, liquid crystal, and TTFTs with the proper electrodes and polarizers. A light guide plate (LGP), a diffuser sheet, and a prism sheet are also used to redirect the light from the LEDs positioned to its sides. Instead of the typical aluminium reflective sheet mirror adjacent to the LOP, in this example, a dielectric cold mirror on top of a silicon solar cell was fabricated separately from the display and positioned behind the LOP. This dielectric cold mirror was directly deposited over the front glass of a polycrystalline silicon solar panel. In this example, the e-reader device interconnects the adjacent display functional layers and the dielectric mirror attached to the solar cell. Both parts could have been connected directly, e.g., by a resin. The dielectric mirror attached to the silicon solar panel can easily be installed behind different display technologies, such as quantum nanorod emitting diode display. These displays should be transparent or semitransparent to at least the high wavelength red part of the visible spectrum and near infra-red wavelengths.

[0033] A fourth example is a photovoltaic display. This display is a QD-OLED. It includes a touch screen glass substrate, covered with green and red photo-emissive quantum dots for the green and red sub-pixels. A TTFT array is interconnected to an ITO anode, an OLED double stack, and an ITO cathode. It produces blue light, which undergoes photoluminescence in the green and red sub-pixels. Subsequently, a buffer layer and a Ti02/Mg-F2 Bragg mirror are directly deposited over the display's cathode. This is a cold mirror with a reflectance threshold of about 670 nm. Alternatively, similar dielectric mirrors may be fabricated from, and are not limited to, layers of the following materials: oxides of metals as titanium, zirconium, tantalum, hafnium, and aluminum; silicon oxide; silicon oxynitride; magnesium fluoride; and zinc sulfide. An infrared absorbing OPV solar cell is then constructed on top of the cold mirror. This integrated display allows photovoltaic activity when exposed to natural or artificial high-wavelength light.

[0034] Several fundamental embodiments of the current invention become apparent from these examples. Among them is the feasibility of employing one or just a few reflective sheets over the entire display. The same applies to the solar cell or solar cells. These are chief advantages over solutions that offer pixel or sub-pixel-sized reflectors or solar cells. Extensive use of the high wavelength red and infra-red regions, color consistency from different viewing angles, and high visible reflectance of the reflective sheet are central as well. Additionally, a reflective sheet as a dielectric cold mirror does not require additional components and electronics to operate consistently and effectively. These and further embodiments, features, and operation mechanisms of the current invention will be clearer to a person skilled in the art as a consequence of the following drawings and claims.

BRIEF DESCRIPTION OF THE FIGURES

[0035] Several key elements of the current invention are provided in the following drawings by way of example. These and the accompanying descriptions portray mechanisms of operation and construction methods. They are not intended to describe boundaries for the scope of the invention. The drawings and layer thicknesses are not drawn to scale for clarity.

[0036] Figure 1 illustrates the main components of a mobile electronic device having a display with solar charging capabilities; [0037] Figure 2 portrays the main functional layers of a monolithic smartphone OLED-OPV display; [0038] Figure 3 exemplifies the construction of a none-monolithic PLED-cold mirror operation together with a monocrystalline solar cell; [0039] Figure 4 describes a dielectric mirror, employed over a multi-Si solar cell which is installed adjacent to an edge-lit LED display of an e-reader, [0040] Figure 5 depicts a monolithic QD-OLED, dielectric mirror, and infra-red absorbing OPV solar cell [0041] Figure 6 displays the modulated reflectance, transmittance, and absorbance of the dielectric mirror of the third specific example detailed in Figure 4, and [0042] Figure 7 demonstrates the graphs of the modulated reflectance of the cold mirror of the third specific example detailed in Figure 4, in angles of incidence of 15, 30, and 45 degrees.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0043] Figure 1 illustrates the main components and operation principle of a general display with solar capabilities according to the current invention in a spread-out fashion. Display 100 includes all parts and functional layers necessary for its operation. It is substantially transparent and lacks a regular reflective sheet as the conventionally applied aluminium back electrode. Instead, a reflective sheet 200, as a cold dielectric mirror, substantially reflects the display emitted light and still allows considerable transmittance in the high wavelength visible and the infra-red regions. To absorb this light and convert it into electric energy, solar cell 300 is positioned behind both display 100 and reflective sheet 200. These components are interconnected to a mobile electronic device 400. Light originated from the display itself may be directed towards the front of the display as the trajectory of ray 500. It may also be emitted towards the backside of the display. Such light beam 510 contains principally visible light under the reflectance threshold of reflective sheet 200. Therefore, it will be reflected back, towards the front of the display as light beam 520. On the other hand, external light above the reflectance wavelength threshold should mainly go across display 100 and reflective sheet 200 to be absorbed in solar cell 300. This solar cell or a plurality of solar cells covers most of the backside of the reflective sheet and converts sunlight or appropriate artificial light into electricity.

[0044] Figure 2 specifies the main functional materials and layers equivalent to the smartphone's display, described in the first specific example above. This display integrates two organic photonic devices. Display part 100 at the front functions as a substantially transparent OLED display. It includes a capacitive multi-touch screen 110, which also acts as a rigid scaffold for the complementary thin layers. Marked as part 120 is a simplified representation of a TTFT array that includes a transparent ITO anode for each of the plurality of transparent thin-film transistors of the myriad sub-pixels of the display. H1L 130 and HTL 140 layers are subsequently applied to facilitate hole injection and transport. The emissive organic layer 150 is an array of organic electro-emissive materials, adjusting an electro-emissive layer for each sub-pixel. Blocking layer 160 is next, followed by ETL 170, buffer layer 180 of 60 nm of W03, and ITO cathode 190. This buffer layer protects the display from the destructive sputtering process of the subsequent ITO layer. Additional buffer layer 199 insulates, in this case, the functional layers of the display from the subsequent reflective sheet 200. This buffer may be beneficial in some cases to allow the fabrication of a dielectric cold mirror with the desired properties directly on top of the display. The reflective sheet does not require the addition of a thick, rigid scaffold other than the display itself It is a dielectric cold mirror fabricated by CVD of alternating TiOVIVIgF, layers. Solar cell 300 concludes this monolithic device. It contains only thin layers which are applied directly over the reflective sheet. This solar cell is an OPV solar cell that contains an ITO anode 301, HTL 302, P3HT donor layer 303, ICBA acceptor layer 304, and ETL 305. As a cathode, aluminium electrode 306 is vaporized on the ETL to conclude the backside of the device. During its operation, light is emitted from the EL layer 150 at the general front touch screen direction 500 or instead deviates towards the backside 510. In the latter case, such a backward leaning ray is redirected by reflective sheet 200 to lean towards the front. This reflected ray is marked in this figure as arrow 520. High wavelength external light 600, as the appropriate segment of sunlight, or a laser beam of a suitable wavelength, can reach the organic parts of the OPV solar cell to generate electricity for the device.

[0045] Figure 3 corresponds to the display of the smartphone described in the second specific example. In resemblance to the previous example, the PLED includes a capacitive multi-touch screen 110, acting also as a scaffold. Additionally, TTFT/ITO array 120, Hit 130, and HTL 140 layers are employed. The PLED emits light from an electroluminescent polymeric layer 155. Following are blocking layer 160, ETL 170, and buffer layer 180. In the current example, an AZO layer 195 is fabricated over this WO, buffer. Another low refractive index buffer layer 199 differentiates the display from the cold mirror in this example. Ten pairs of alternating Ti02/Si02 thin layers are then directly deposited over the AZO cathode, acting as dielectric cold mirror 200, which has a reflectance threshold in this case of about 700 nm. This mirror is built only by the mentioned thin layers and adhered to the display because of its direct deposition processes. Separately manufactured monocrystalline silicon solar cell 300 is then installed behind the display-cold mirror component. The gap 20 in between, may be filled with a transparent material, kept empty, or be held to a minimum by the physical installation of the display directly over the display-cold mirror. In this case, an air gap of about 0.2 mm is maintained. External inbound light in the range of approximately 700 nm to the threshold of the silicon solar cell, of near 1100 nm, will be able to operate the solar cell with high average external quantum efficiency, 100461 Figure 4 corresponds to the main layers of the display of the e-reader mentioned in the third specific example. This is of a semitransparent edge-lit LED display 100, coupled with a cold mirror and a crystalline silicon solar cell. Said display 100 is separately manufactured, and the solar cell-cold mirror apparatus is installed adjacently instead of an aluminium reflector. Glass substrate 321 is covered by a transparent conductive layer 322. Next are layered the polycrystalline silicon solar cell functional layers 323 and a metal contact 324, which seals the solar cell construction. On the other side of glass substrate 321, layers 220 through 201 are then correspondingly applied by physical vapor deposition. The first dielectric mirror layer, counted from the front side of the display, is a silicon dioxide layer 201, which is 222 nm thick. The second one is a titanium dioxide layer 202 of 60 nm. The following Si02/TiO2 alternating layers thicknesses are 128 nm, 58 nm, 97 nm, 72 nm, 98 nm, 53 nm, 98.4 nm, 74 nm, 85 nm, 40 nm, 67 nm, 43 nm, 82.3 nm, 48 nm, 83 nm, 42 nm, 47 nm, and 41 nm correspondingly. The modulated photonic characteristics of this ten-pair dielectric cold mirror are detailed in Figures 6 and 7. This solar cell is installed with the dielectric mirror facing the display. The resulting gap 30 is minimized by adjacent installation. Said solar panel covers a substantial part of the backside of the screen to maximize its power output.

100471 Figure 5 depicts the layers of the display of the fourth specific example. It is a monolithic QD-OLED interconnected to a cold mirror and an OPV solar cell. The display includes a capacitive multi-touch screen 110, which operates by the initial production of blue light by an OLED. Different photoluminescent quantum dots absorb this blue light. Subsequently, filters 702 and 703 refine green and red light sub-pixels correspondingly, whereas the blue sub-pixel does not require such a filter but merely a transparent filler 701. The following layer fits the appropriate quantum dots for the green sub-pixel 705 and red sub-pixel 706. Yet, the blue sub-pixel does not require photoluminescence but only spacer 704. ITO anode 707 is the following layer. Next are EIL 708, ETL 709, and blocking layer 710, which facilitate electron flow to the organic blue electro-emissive layer 711. HTL 712 and HIL 713 conclude the upper stack of the OLED part. EIL 714, ETL 715, blocking layer 716, blue-emitting layer 717, HTL 718, and EIL 719 form the lower stack of the OLED. A 60 nm WO; buffer layer 720 protects the OLED stacks, and the following is the TTFT/ITO array 721. The latter fits an ITO cathode for each of the plurality of sub-pixels of the display that can be turned on and off by the TTFT during the display operation. Extra buffer layer 251 separates the QD-OLED part from the reflective sheet part 252. This is a dielectric mirror, also known as a Bragg mirror. Deposition of alternating Ti02/1\4gF2 layers forms this mirror by a CVD process. An OPV solar cell is assembled on top of the dielectric mirror to form the third photovoltaic section. This is an infra-red threshold solar cell commencing with ITO anode 351, sputtered directly over the reflective sheet. Thereafter, a zinc oxide layer 352 is followed by the infra-red absorbing organic dispersed heterojunction layer 353, molybdenum oxide 354 layer, and silver cathode 355.

[00481 Figure 6 exhibits the modulated reflectance, transmittance, and absorbance of the reflective sheet of the third specific example. This Si02/Ti02 dielectric mirror is built from ten pairs of alternating oxides. The various thicknesses of the layers are specified in the description of Figure 4. This modulation takes into account an ITO back medium and incident light in zenith from the front of the screen, entering perpendicularly to layer 201 first. Reflectance graph 800 exhibits high reflective properties in the part of the visible region extending from 400 nm to about 700 nm. That matches the reflectance properties of an aluminium reflective sheet in that range. High transmittance properties of the same dielectric mirror above the reflectance threshold are drawn in graph 801. It allows much of the sunlight or high wavelength artificial light to reach succeeding solar cells. The high transparency of all reflective sheet materials causes the absorbance graph 802 to be minimal and be noticeable only in a small hillock near 400 nm. In addition, the high reflectance across most of the visible spectrum is utilized for a mirror effect.

[00491 Figure 7 demonstrates modulated reflectance graphs of the dielectric mirror exhibited in the third specific example and having its properties elaborated on in Figures 4 and 6. Graph 815 is of the reflectance at an angle of incidence of 15 degrees, and graphs 830 and 845 are at angles of incidence of 30 and 45 degrees, respectively. Prominently, there is a very small deviation between the graphs at 15 degrees and the 0 degrees (at zenith) shown in Figure 6. Larger angles as 30 and 45 degrees demonstrate that the threshold of this reflective sheet may divert to slightly smaller wavelengths. Nevertheless, even at 45 degrees view, the reflective sheet efficiently reflects display-generated light. Importantly, in all of this wide range of angles of incidence, the high visible reflectance below the threshold remains consistent. Therefore color changes in different viewing angles due to this reflective sheet should be minute. Display radiation fraction of a higher wavelength than the mirror threshold is small, even when considering a smaller, 45 degrees angle of incidence threshold. Still less perceptive is this light due to inefficient absorbance in the human eye retina. Some reflectance variations may occur with the angle of incidence at high wavelengths. Changes like this, as the one of graph 845 at around 920 nm, should result in small effects concerning the solar cell power output, yet none for the display's performances.

Claims (20)

1. CLAIMS[0050] What is claimed is: 1 A mobile electronic device comprising at least: a. a display comprising at least one light -emitting layer, transistor array, and reflective sheet; and b. at least one solar cell; wherein: said reflective sheet has the attribute of average reflectance of at least 60% of the electromagnetic radiation in the range between 400 nm to 650 nm and at least 60% transmittance in the range between 750 nm to 1100 nm; said display allows substantial transmittance of light hi the range between 750 nm to 1100 nm; said solar cell face the back of said display, including its light-emitting layer(s), transistor array, and reflective sheet, is positioned behind these components, and cover at least a part of the display's area; said average reflectance and transmittance are determined by perpendicular measurements to the surface.
2. 2. The mobile electronic device of claim 1, wherein said reflective sheet is included in at least one of the following group: dielectric mirrors; distributed Bragg reflectors; and reflectors having alternating layers or gradients of different refraction indices materials.
3. 3. The mobile electronic device of claim 1, wherein said mobile electronic device belongs to the following group which contains a display: smartphones; tablets; laptop computers; electronic watches; digital cameras; e-readers; cellular phones; smart watches; and satellite navigation devices.
4. 4. The mobile electronic device of claim 3, wherein said solar cell( s) belongs to the following group of types: silicon-based solar cells, including amorphous silicon solar cells (a-Si), crystalline silicon solar cells (c-Si), rnonocrystalline silicon solar cells (mono-Si), and polycrystalline silicon solar cells (multi-Si); copper indium gallium selemide solar cells (CI(G)S); organic solar cells (OPV); and quantum dot solar cells.
5. 5. The mobile electronic device of claim 3, wherein said display belongs to the following group: OLED, including AMOLED. W-OLED and QDOLED technologies; quantum nanorod emitting diode; polymer light-emitting diode (PLED); clectroluminescent quantum dots displays (ELQLED); micro-LED; QLED; and liquid crystal display (LCD) technologies, including edge-lit LCDs and backlit LCDs.
6. 6. The mobile electronic device of claim 3, wherein said reflective sheet is deposited directly over other display layers, as a substrate, to form a monolithic display with said reflective sheet, or the solar cell(s) is deposited directly over the reflective sheet, as a substrate, to form a monolithic reflective sheet with solar cell(s), or both cases, to form a monolithic triple: display-reflective sheet-solar cell(s).
7. 7. The mobile electronic device of claim 3, wherein said mobile electronic device further comprising at least one additional distributed Bragg reflector, dielectric mirror, Fresnel reflector, or retroreflector, wherein: this reflector is configured to retrieve an electromagnetic signal to allow the device localization for an artificial light source focus on the display.
8. 8. A photovoltaic display apparatus comprising at least: a. a display comprising at least one light-emitting layer, transistor array, and reflective sheet which is a dielectric mirror; b. at least one solar cell; wherein: said reflective sheet is able to substantially reflect visible display light which is directed away from the front of the display, towards the front surface of the display; said display, including its reflective sheet, allows a substantial transmittance of external inbound light in the near infra-red range; said solar cell is facing about the back of the display, including its light emitting layer(s), transistor array, and reflective sheet, is positioned behind these components, and can absorb at least a part of external light that passes through said display and its reflective sheet, to produce electric energy.
9. 9. The photovoltaic display apparatus of claim 8, wherein said photovoltaic display apparatus external quantum efficiency, by the operation of said solar cell, in at least a part of the range between 800 nm and 1100 nm is at least twice than the average external quantum efficiency in the range between 400 nm to 650 nm.
10. 10. The photovoltaic display apparatus of claim 8, wherein said display belongs to the following group: OLED (including OLED based technologies as AMOLED W-OLED and QD-OLED); quantum nanorod emitting diode; polymer light-emitting diode (PLED); electrolunnnescent quantum dots displays (EL-QLED); micro-LED; QLED; and Liquid crystal display (LCD), including Edge-lit LCDs and backlit LCDs.
11. 11. The photovoltaic display apparatus of claim 8, wherein said reflective sheet's reflectance average is above 70% in the range of 400 nm to 650 nm and its transmittance average is above 70% in the range of 750 nm to 1100 nm.
12. 12. The photovoltaic display apparatus of claim 8, wherein said photovoltaic display apparatus is further configured to fit at least one of the following group of electronic devices: smartphones; tablets; laptop computers; mobile computers; electronic watches; digital cameras; e-readers; cellular phones; smartwatches; satellite navigation devices; electronic signs; bus stop information electronic display panels; train station electronic sign display panels; televisions; wearable displays; dynamic message signs; handheld game consoles; pocket calculators; digital media players containing a display; and electronic traffic signs.
13. 13. The photovoltaic display apparatus of claim 12, wherein said photovoltaic display apparatus further comprising at least one additional signal reflector which is a reflector from the following group: distributed Bragg reflector; dielectric mirror; Fresnel reflector; and retroreflector; Said signal reflector(s) is interconnected directly or indirectly to said photovoltaic display apparatus; embedded in, or between any parts of said photovoltaic display; or that at least a part of said reflective sheet of said photovoltaic display apparatus is further configured as said signal reflector(s) for external inbound signal wherein: this signal reflector is configured to retrieve an electromagnetic signal to allow the device localization for an artificial light source focus on the display.
14. 14. A solar display comprising at least: a. a display comprising at least one light-emitting layer, transistor array, and reflective sheet; b. at least one solar cell; wherein: said display allows substantial transmittance at a substantial part of the wavelength range between 750 nm and 1100 nm; said reflective sheet is able to reflect a substantial part of the visible light in the range between 400 nm to 650 nm, and is included in at least one of the following group: dielectric minors; distributed Bragg reflectors; and reflectors having alternating layers or gradients of different refraction indices materials; said solar cell is positioned about behind said display, including its light-emitting layer(s), transistor array, and reflective sheet, about facing it, and can generate electricity by inbound light passing through said display.
15. 15. The solar display of claim 14, wherein said display's technology belongs to one of the following group: OLED, including AMOLED, W-OLED and QD-OLED technologies; quantum nanorod emitting diode; polymer light-emitting diode (PLED); electroluminescent quantum dots displays (EL-QLED); and micro-LED.
16. 16 The solar display of claim 14, wherein said solar display is further configured to fit at least one of the following groups of electronic devices: smartphones; tablets; laptop computers; mobile computers; electronic watches; digital cameras; e-readers; cellular phones; smartwatches; satellite navigation devices; electronic signs; bus stop information electronic display panels; train station electronic sign display panels; televisions; wearable displays; dynamic message signs; handheld game consoles; pocket calculators; digital media players containing a display; and electronic traffic signs.
17. 17 The solar display of claim 14, wherein said solar display further comprising one or more solar cells of at least one of the following group: UV converting solar cells positioned in front of the light emitting layers of said display; solar cells positioned about to the side of said display in about a perpendicular fashion.
18. 18 The solar display of claim 14, wherein the electric charging power of the solar display by its solar cell(s), measured over at least a part of the solar display, in the range between 800 nm and 1050 nm of the AM1.5G solar spectrum standard, is at least twice than the electric charging power of the solar display by its solar cell(s), in the range between 400 nm to 650 nm of the AM1.5G solar spectrum standard, measured at about the same place.
19. 19. The solar display of claim 14, wherein: a. said display and said reflective sheet are interconnected by at. least one of the following options: direct fabrication of the reflective sheet over other display components; interconnection by any physical or chemical means; indirect interconnection by a mobile electronic device which is interconnected to these components; and b. said reflective sheet of said display and said solar cell are interconnected by at least one of the following options: direct fabrication of one component over the other; interconnection by any physical or chemical means; indirect interconnection by a mobile electronic device which is interconnected to these components.
20. 20. The solar display of claim 16, wherein said solar display is further configured to efficiently convert laser beam energy into electric energy for one or more laser beams in wavelength(s) higher than 650 nm.