Electronic device equipped with a solar cell, and method for manufacturing the solar cell.

Abstract

The present invention relates to a solar cell (10) comprising a substrate (100) made of a transparent material intended to be exposed to optical radiation, a first electrode (110) formed on the substrate (100), and a unit solar cell (130) arranged between said first electrode (110) and a second electrode (120), the first electrode (110, 120) being made of an electrically conductive transparent material, the unit solar cell (130) being adapted to absorb optical radiation and generate an electric current at the terminals of said first electrode (110, 120) and said second electrode (120) and said unit solar cell (130) being perforated to allow optical radiation to pass through said solar cell (10).

Description

Technical Field

[0001] The present invention relates to the field of solar cells for supplying electrical energy to electronic devices.

[0002] More particularly, the present invention relates to an electronic device provided with a solar cell intended to supply electrical energy, for example, to motor means or display means of a watch movement.

Background Art

[0003] In certain applications such as the watch field, aesthetics is an important requirement. This has led to the development of so-called "translucent" solar cells intended to be hidden from view.

[0004] This type of solar cell consists of unit solar cells arranged between a first electrode made of a transparent material and disposed on a transparent substrate, and a second electrode made of an opaque metallic material, as described in French Patent Invention No. 2681189.

[0005] The solar cell has trenches and perforations that extend through the second electrode and the unit solar cells and allow a part of the incident light to pass through the solar cell. These trenches and perforations are dimensioned and arranged to provide transparency to the solar cell for the user to see with the naked eye.

[0006] Of course, the greater the surface area of the solar cell covered by the holes and / or trenches, the higher the transparency of the solar cell and the lower its electrical efficiency. Conversely, the smaller the surface area, the lower the transparency of the solar cell and the higher its electrical efficiency.

[0007] Therefore, the need to make the solar cell aesthetically pleasing sacrifices the electrical efficiency of the cell, so it is necessary to find a compromise between the level of transparency of the cell and its electrical efficiency.

[0008] Therefore, it is necessary to improve the electrical efficiency of translucent solar cells without compromising transparency and / or aesthetics. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] French Patent No. 2681189 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The present invention solves the aforementioned drawbacks by providing an electronic device equipped with a solar cell designed to supply electrical energy at a level sufficient to supply power, i.e., with high efficiency, while also meeting the aesthetic requirements of the electronic device to which the solar cell is attached, such as a timekeeping device. [Means for solving the problem]

[0011] For this purpose, the present invention relates to an electronic device comprising a solar cell comprising a substrate made of a transparent material intended to be exposed to light radiation, a first electrode formed on the substrate, and a unit solar cell disposed between the first electrode and a second electrode.

[0012] The first and second electrodes are made of a conductive and transparent material.

[0013] The solar unit is adapted to absorb light radiation, i.e., light radiation transmitted through the substrate, and generate a voltage at the terminals of the first and second electrodes. The second electrode and the solar unit are perforated by cavities within the solar cell so that light radiation can pass through the solar cell.

[0014] The electronic device further comprises a reflective element configured to reflect at least a portion of the light radiation, and positioned such that a unit solar cell is exposed to the reflective portion of the light radiation.

[0015] Therefore, because the second electrode of the unit solar cell is transparent, it can absorb not only light radiation transmitted through the substrate but also reflected light radiation.

[0016] Therefore, thanks to the present invention, the unit solar cell can absorb more light rays than those used in the prior art, and its efficiency is greatly improved.

[0017] In certain embodiments, the present invention may further include one or more of the following features, which should be considered individually or in any technically possible combination.

[0018] In certain embodiments, the first electrode is perforated by the cavity of the solar cell.

[0019] In certain embodiments, the unit solar cell is made of amorphous silicon and consists of three stacked layers that form a PIN diode.

[0020] In certain embodiments, the substrate is made of glass, sapphire, or polymer.

[0021] In certain embodiments, the first and second electrodes are made of a transparent conductive oxide such as zinc oxide or indium tin oxide.

[0022] In certain embodiments, the second electrode and the unit solar cell are perforated by a cavity. Advantageously, the cavity may have a hexagonal cross-section.

[0023] Alternatively, the cross-section of the cavity may have any kind of regular or irregular shape, having a simple or complex geometric shape, in order to form a paving on the first electrode.

[0024] In certain embodiments, the solar cell comprises a first electrode and a second electrode, and a protective coating made of a transparent material covering the unit solar cell. For example, the protective coating is made of parylene, polyimide, nitride, or oxide.

[0025] In certain embodiments, the unit solar cell has a through hole for guiding the first electrode to the second electrode so as to enable connection between two terminals.

[0026] The present invention further relates to a timepiece formed by the aforementioned electronic device, comprising a case with a middle, a crystal, and a back cover that define an internal volume in which a timepiece movement supplied with electrical energy by a solar cell is housed, and optionally a dial, wherein a reflective element is formed by the dial or the timepiece movement.

[0027] The timepiece further comprises the above-described solar cell configured to supply electrical energy to the timepiece movement, and the dial is interposed between the solar cell and the timepiece movement.

[0028] More specifically, the solar cell is interposed between the crystal and the timepiece movement, or, when the dial is included in the timepiece, between the crystal and the dial.

[0029] In a particular embodiment of the present invention, the solar cell is fixed to the crystal such that the substrate is pressed against the crystal inside the case with the second electrode facing the internal volume.

[0030] In a particular embodiment of the present invention, the crystal is formed by the substrate with the solar cell arranged such that the second electrode faces the internal volume. <00,00107> In a particular embodiment of the present invention, the solar cell is fixed to the dial such that the substrate is pressed against the dial with the second electrode facing the crystal.

[0032] In a particular embodiment of the present invention, the dial is formed by a substrate with a solar cell positioned such that the second electrode faces the crystal.

[0033] Another aspect of the present invention relates, for example, to a method for manufacturing a solar cell according to the above, comprising the following sequence of steps, namely: - Depositing a first electrode in the form of a transparent conductive layer onto a transparent substrate, - Depositing a unit solar cell adapted to absorb light radiation and generate an electric current onto a first electrode, - Patterning the unit solar cell on a predetermined area, - Depositing a second electrode in the form of a transparent conductive layer on the unit solar cell and a predetermined area, - The method comprises patterning the second electrode and the unit solar cell on a predetermined area so as to electrically insulate the first electrode and the second electrode.

[0034] The patterning step of the solar cell allows for the creation of cavities within the solar cell.

[0035] In a particular embodiment of the present invention, the first electrode is perforated during the step of patterning the second electrode and the unit solar cell.

[0036] In a particular embodiment of the present invention, the first electrode and the second electrode, as well as the unit solar cell, are enclosed in a transparent material that forms a protective coating.

[0037] In a particular embodiment of the present invention, the first electrode and the second electrode are deposited by physical vapor deposition or chemical vapor deposition.

[0038] In a particular embodiment of the present invention, the unit solar cell is deposited by plasma chemical vapor deposition.

[0039] In a particular embodiment of the present invention, the step of patterning the second electrode and the unit solar cell is performed in a single operation.

[0040] In a particular embodiment of the present invention, the step of patterning the second electrode and the unit solar cell is performed by a dry etching method.

[0041] In a particular embodiment of the present invention, the step of patterning the second electrode and the unit solar cell is performed by reactive ion etching, wet etching, or a combination of dry etching and wet etching.

[0042] Other features and advantages of the present invention will become apparent from the following detailed description, which is given as an example and is not limited to the accompanying drawings. [Brief explanation of the drawing]

[0043] [Figure 1] Figure 1 is a schematic cross-sectional view of a solar cell according to the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view of the solar cell of Figure 1 at different steps of the manufacturing method according to the present invention. [Figure 3] Figure 3 is a schematic cross-sectional view of the solar cell of Figure 1 at different steps of the manufacturing method according to the present invention. [Figure 4] Figure 4 is a schematic cross-sectional view of the solar cell of Figure 1 at different steps of the manufacturing method according to the present invention. [Figure 5] Figure 5 is a schematic cross-sectional view of the solar cell of Figure 1 at different steps of the manufacturing method according to the present invention. [Modes for carrying out the invention]

[0044] The description of the present invention is given in relation to its application to electronic devices formed by timekeeping devices, such as wristwatches. However, it goes without saying that the present invention is not limited to this application and can be advantageously used with any other electronic devices.

[0045] It should also be noted that the term "transparent" in this book can also refer to the ability of a material to allow all or part of light rays, especially light visible to the naked eye, to pass through.

[0046] A solar cell 10 according to a preferred embodiment of the present invention is adapted to convert light radiation into an electric current for supply via a power supply circuit to a motor or display means of a timer. The power supply circuit and motor or display means of a timer are well known to those skilled in the art and are not relevant to the present invention. Therefore, they are not described in detail below and are not illustrated.

[0047] The timepiece comprises a case including a middle section, a crystal, and a case back. The case defines an internal volume for housing a clock movement, which comprises a power supply circuit, the aforementioned motor or display means, and optionally a dial. The components and configurations of these timepieces are well known to those skilled in the art.

[0048] In a preferred exemplary embodiment of the present invention, the solar cell 10 is positioned between the crystal and the dial.

[0049] As shown in Figure 1, the solar cell 10 comprises a substrate 100 made of a transparent material intended to be exposed to light radiation through a first surface 101. In alternative embodiments, the light radiation is either incident radiation or transmitted radiation. In Figure 1, incident radiation or transmitted radiation is symbolized by a thick arrow 20.

[0050] The substrate 100 is made from polymers such as glass, sapphire, or polyethylene naphthalate, also known as the acronym "PEN," or polyethylene terephthalate, also known as the acronym "PET." Other possibilities include polymers such as polycarbonate, also known as the acronym "PC," or polymethyl methacrylate acrylic, also known as the acronym "PMMA."

[0051] The substrate 100 can be fixed in place, for example, by adhesive bonding, or by mechanical or physical means such as ionic bonding or pulsed current bonding at its periphery, so that its first surface 101 is positioned relative to the crystal. Therefore, the light radiation received by the first surface 101 of the substrate 100 is radiation that passes through the crystal.

[0052] Alternatively, the substrate 100 can constitute the crystal of the timer. Therefore, the light radiation received by the first surface 101 of the substrate 100 is incident radiation.

[0053] In this particular case, the substrate 100 may be treated with an anti-reflective coating on its first surface 101 in order to maximize the amount of light radiation received through the substrate.

[0054] The solar cell 10 further comprises a first electrode 110 formed on all or part of the surface of the second surface 102 of the substrate 100. This first electrode 110 is directly exposed to light radiation transmitted through the substrate 100, which results from radiation passing through the substrate 100.

[0055] As shown in Figure 1, the unit solar cell 130 is positioned between the first electrode 110 and the second electrode 120.

[0056] In this alternative embodiment of the present invention, the second electrode 120 is intended to face the internal volume of the case.

[0057] The first electrode 110 and the second electrode 120 are connected to each other via a unit solar cell 130 and are made of a transparent conductive material such as a transparent conductive oxide, also known as the acronym "TCO". Such a transparent conductive oxide can be zinc oxide or indium tin oxide.

[0058] The unit solar cell 130 is adapted to absorb light radiation and generate an electric current at terminals 111 and 112 of the first electrode 110 and the second electrode 120.

[0059] As shown in Figure 1, the unit solar cell 130 has a through hole 131 on the same surface of the substrate 100, which in this case is the second surface 102, that allows the first electrode 110 to be guided to the second electrode 120, enabling a simple connection between the two terminals 111, 112.

[0060] Terminals 111 and 112 are covered with a layer of conductive material, such as silver paste or other metallic material, to improve their conductivity. This layer of conductive material is deposited by any printing or material deposition technique known to those skilled in the art, such as physical vapor deposition.

[0061] More specifically, the unit solar cell 130 consists of multiple, for example, three stacked thin layers (not shown) made of amorphous silicon.

[0062] These three thin layers form a PIN diode, and one of these layers forms an intrinsic region sandwiched between the p-region and the n-region. The design of such a PIN diode is known to those skilled in the art and will not be described in further detail in the remainder of this book.

[0063] As shown in Figure 1, the second electrode 120 and the unit solar cell 130 are perforated so that transmitted radiation can pass through the solar cell 10.

[0064] More specifically, the solar cell 10 includes cavities 140 that pass through the second electrode 120 and the unit solar cell 130. These cavities 140 are blind in the sense that they do not extend into the substrate 100. Thus, each cavity 140 forms a coaxial through-hole in the second electrode 120 and the solar cell 130, as shown in Figure 1.

[0065] Therefore, transmitted radiation can pass through the solar cell 10 while the substrate 100 and the first electrode 110 are transparent, and a portion of this transmitted radiation can be reflected by the reflective element 150 of the electronic device.

[0066] In a preferred application of the present invention, such an element is comprised of a timekeeping dial or a clock movement.

[0067] In an alternative embodiment, the first electrode 110 can be further perforated to maximize the transparency of the solar cell 10. Thus, the cavity 140 passes through the first electrode 110, the second electrode 120, and the unit solar cell 130. Thus, each cavity 140 forms a coaxial through-hole to the first electrode 110, the second electrode 120, and the solar cell 130.

[0068] The dial or watch movement is adapted to reflect a portion of the light radiation that passes through the cavity 140 of the solar cell 10, i.e., the radiation that passes through the substrate and the first electrode 110. For example, the dial or watch movement is adapted to reflect more than 50% of the received light radiation.

[0069] The reflected portion of light emission is referred to as "reflected radiation" in the remainder of this book and is symbolized by a thin arrow 30 in Figure 1.

[0070] Advantageously, the solar cell unit 130 can absorb some of the radiation transmitted through the substrate and some of the radiation reflected by the dial or watch movement.

[0071] Since the second electrode 120 is made of a transparent material, the light-absorbing surface area of ​​the solar unit 130 is increased, and therefore the efficiency of the solar unit 130 is increased.

[0072] Advantageously, the cavity 140 can have a hexagonal cross-section. This shape has the advantage of minimizing electrical losses.

[0073] Alternatively, the cross-section of the cavity 140 may have any kind of regular or irregular shape with simple or multiple geometric shapes in order to form paving on the first electrode 110. For example, the cavity 140 may be filamentous, such as a groove, or polygonal, such as a triangle or square, or a shape such as letters or a logo.

[0074] The solar cell 10 may include a protective coating (not shown) made of a transparent material that encloses the first electrode 110 and the second electrode 120, as well as the unit solar cell 130. This protective coating protects the solar cell 10 from external attacks and contamination.

[0075] Such protective coatings can be made from parylene, polyimide, nitride, or oxide.

[0076] In another alternative embodiment of the present invention, the substrate 100 can be fixed, for example, by adhesive or mechanical fastening means at its periphery, such that the first surface 101 is positioned relative to the dial or watch movement.

[0077] Alternatively, the substrate 100 can form a dial. Therefore, the second electrode 120 is intended to face the crystal.

[0078] Therefore, the solar cell unit 130 can absorb some of the radiation that passes through the crystal and some of the radiation that is reflected by the watch movement.

[0079] The present invention further relates to a method for manufacturing a solar cell, for example, one that conforms to the solar cell 10 described above.

[0080] This manufacturing method consists of the following sequential steps, illustrated chronologically in Figures 2 through 5 and Figure 1, respectively: - A first electrode 110 in the form of a transparent conductive layer is deposited on a transparent substrate 100, - A unit solar cell 130 adapted to absorb light radiation and generate an electric current is deposited on the first electrode 110, - Patterning the unit solar cell 130 on a predetermined area to form through holes 131, - A second electrode 120 in the form of a transparent conductive layer is deposited on the unit solar cell 130 and a predetermined area so as to fill the through-hole 131. - The method includes patterning the second electrode 120 and the unit solar cell 130 on a predetermined area in order to electrically insulate the first electrode 110 and the second electrode 120.

[0081] The patterning step allows for the formation of multiple cavities 140 within the solar cell 10.

[0082] The first electrode can be further patterned during this patterning step.

[0083] Advantageously, by carrying out the method according to the present invention, several solar cells can be formed in parallel or in series.

[0084] In a final step not shown, the first electrode 110 and the second electrode 120, as well as the unit solar cell 130, can be sealed with a transparent material that forms a protective coating.

[0085] In particular, this final step can be carried out using a material deposition method that varies depending on the material selected to form the protective coating. For example, the final step can be carried out by chemical vapor deposition if the protective coating material is parylene, by centrifugal coating if the protective coating material is polyimide, or by plasma chemical vapor deposition (CVD or ALD) if the material selected to form the protective coating is an oxide. The protective coating can also be deposited by physical vapor deposition, evaporation, or cathode sputtering, for example, if the protective coating is made from a nitride.

[0086] The step of depositing the first electrode 110 and the second electrode 120 can be carried out by physical vapor deposition or chemical vapor deposition.

[0087] Furthermore, the unit solar cell 130 can be deposited by plasma chemical vapor deposition.

[0088] Advantageously, the steps of patterning the second electrode 120 and the unit solar cell 130 can be performed in a single operation. This arrangement is made possible by a particular design of the solar cell 10 according to the present invention.

[0089] The patterning step can be performed by a dry etching method, such as reactive ion etching, a wet etching method, or a combination of dry etching and wet etching methods.

Claims

1. A timepiece comprising a watch movement supplied with electrical energy by a solar cell (10), a case having a middle, a crystal, and a case back that define the internal volume in which the watch movement is housed, and an electronic device, The electronic device comprises a solar cell (10) comprising a substrate (100) made of a transparent material intended to be exposed to light radiation, a first electrode (110) formed on the substrate (100), and a unit solar cell (130) disposed between the first electrode (110) and a second electrode (120), The solar cell (10) is configured such that the first electrode and the second electrode (110, 120) are made of a transparent conductive material, the unit solar cell (130) absorbs light radiation and generates an electric current at the terminals (111, 112) of the first electrode and the second electrode (110, 120), the second electrode (120) and the unit solar cell (130) are perforated by a cavity (140) of the solar cell (10) so that light radiation can pass through the solar cell (10), the cavity (140) having a hexagonal cross-section, The electronic device further comprises a reflective element (150), the reflective element (150) configured to reflect at least a portion of the light radiation, and the unit solar cell (130) is positioned to be exposed to the reflective portion of the light radiation. The reflective element (150) is formed by the clock movement, The second electrode (120) faces the internal volume, A timekeeping device in which the crystal is formed by the substrate (100).

2. The timer according to claim 1, wherein the first electrode (110) is perforated by the cavity (140).

3. The timer according to claim 1, wherein the unit solar cell (130) is made of amorphous silicon and consists of three stacked layers forming a PIN diode.

4. The timer according to claim 1, wherein the substrate (100) is made of glass, sapphire, or polymer.

5. The timer according to claim 1, wherein the first electrode and the second electrode (110, 120) are made of a transparent conductive oxide.

6. The timer according to claim 5, wherein the first electrode and the second electrode (110, 120) are made of zinc oxide or indium tin oxide.

7. The timer according to claim 1, comprising a coating made of a transparent material covering the first electrode and the second electrode (110, 120), and the unit solar cell (130).

8. The timer according to claim 7, wherein the coating is made of parylene, polyimide, nitride, or oxide.

9. The timer according to claim 1, wherein the unit solar cell (130) has a through hole (131) for guiding the first electrode (110) to the second electrode (120) so as to enable connection between the two terminals (111, 112).

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