EP2984211A1

EP2984211A1 - Method and device for electrodeposition in cylindrical geometry

Info

Publication number: EP2984211A1
Application number: EP14719044.1A
Authority: EP
Inventors: Grégory SAVIDAND; Nicolas LOONES; Daniel Lincot; Elisabeth Chassaing
Original assignee: Electricite de France SA; Centre National de la Recherche Scientifique CNRS
Current assignee: Electricite de France SA; Centre National de la Recherche Scientifique CNRS
Priority date: 2013-04-10
Filing date: 2014-03-25
Publication date: 2016-02-17
Also published as: US20160083861A1; FR3004466A1; WO2014167201A1; TW201441425A; JP2016519720A; TWI507567B; US10167565B2; CN105324518B; SG11201508392QA; CN105324518A; FR3004466B1

Abstract

A method and device for electrodeposition in cylindrical geometry. The invention relates to a method for electrochemically depositing a thin layer on a flexible substrate, comprising the following steps: -providing, in an electrolysis bath, a first closed cylinder in a second hollow cylinder, -applying the flexible substrate to one of the surfaces chosen from the outer surface of the first cylinder and the inner surface of the second cylinder, the flexible substrate forming a first electrode, -providing, in the electrolysis bath, a second electrode, and -applying a potential difference between the first electrode and the second electrode in order to electrodeposit the thin layer on the flexible substrate.

Description

Method and device for electro-deposition in cylindrical geometry

TECHNICAL AREA

The invention relates to the field of electro-deposition technologies of conductive and semiconductor compounds on flexible substrates of metals.

TECHNOLOGICAL BACKGROUND

The manufacture of photovoltaic panels, in particular so-called "flat-plate" panels involving thin layers, involves processes for depositing compounds of columns 11, 12, 13, 14 and 16 of the periodic table, for example those based on Cu, Zn, Sn, In, Ga, Al, Se, S as well as compounds based on selenides, tellurides or sulphides. These deposits are traditionally made by two types of technologies: so-called "batch" processes, associated with rigid substrates, or those called "roll to roll", integrating flexible substrates unrolled over an entire production line.

The "roll to roll" process has the advantage, from an industrial point of view, of reducing the mass of the panels and of increasing the production rate compared to "batch" processes, thus reducing manufacturing costs. Nevertheless, the transition from "batch" processes to "roll to roll" processes requires performance validation steps.

Indeed, "roll-to-roll" technologies are currently not as well-known as "batch" technologies, which deprives devices involving flexible substrates of precise, economical and reliable manufacturing processes.

Document US 6406610 proposes an electrolytic bath in which a flexible substrate is quenched by moving past an anode. The document DE 19751021 also proposes an electrolysis device using a roll-to-roll process, operating by moving a flexible substrate in a bath containing an anode.

The techniques proposed in these documents, however, use vessels whose geometry does not optimize the homogenization of the solution present in the electrolysis bath. In addition, these tanks could benefit from an optimization aimed at reducing the quantity of solution necessary for electro-depositing. More advantageous geometries are known in batch processes. In particular, a cylindrical geometry, such as that described in document US Pat. No. 5,628,884, makes it possible to take advantage of the hydrodynamic control by putting a cylindrical rigid substrate in rotation about its axis in an electrochemical bath contained in a vessel that is itself cylindrical.

There is therefore a need to optimize the electro-deposition technologies used to manipulate flexible substrates, so as to benefit both from certain advantages offered by known technologies and used in "batch" processes while benefiting from gains in production cost and speed of roll-to-roll technologies. SUMMARY OF THE INVENTION

To achieve this, the present invention provides a method of depositing a thin layer on a flexible substrate, by electrochemistry, comprising the following steps:

to provide, in an electrolysis bath, a first closed cylinder in a second hollow cylinder,

applying the flexible substrate to one of the surfaces of the outer surface of the first cylinder and the inner surface of the second cylinder, the flexible substrate forming a first electrode,

- providing, in the electrolysis bath, at least a second electrode, and

- Applying a potential difference between the first electrode and the second electrode for electro-depositing the thin layer on the flexible substrate.

There are two possible configurations for positioning the substrate. The latter can be placed on the outer surface of the closed cylinder or on the inner surface of the hollow cylinder. Advantageously, the substrate forms a cathode. The second electrode is advantageously an anode and may be on a third cylinder introduced into the electrolysis bath, or on the other of the cylindrical surfaces present in the electrolysis bath or be a substantially flat electrode immersed in the bath of electrolysis. 'electrolysis.

This method has the advantage of allowing a saving in volume of electrolytic solution used. Indeed, in cylindrical geometry the electrolytic solution is contained between the outer surface of the closed cylinder and the inner surface of the cylinder hollow forming a tank. The cylindrical geometry reactor does not involve stirring system to homogenize the solution. The distance separating the cathode from the tank is therefore small and makes it possible to save electrolytic solution. Moreover, this geometry is particularly suitable for flexible substrates because they follow a large, curved surface on cylinders less bulky than the electrolysis cells parallelepiped geometry.

The cylindrical geometry for electro-deposition on flexible substrate also makes it possible to control more precisely the deposition parameters of chemical elements on the substrate. In particular, the electro-deposition rate or the composition of the deposit can be controlled at least with the aid of several distinct parameters such as, the concentration of electroactive species in the solution, and the electric current flowing between the two electrodes, the applied potential and rotational speed.

The application of a potential difference between the first electrode and the second electrode can be achieved by applying a current between the two electrodes, or by applying a voltage between these electrodes.

The first electrode is a cathode, while the second electrode is an anode. It may be possible to provide an additional reference electrode.

Additional steps can be implemented to improve the electro-deposition process.

Thus, it is possible to rotate the first cylinder about its axis during electro-deposition.

This rotation makes it possible to dispense with stirring systems in order to homogenize the electrolytic solution. In addition, the control of the speed of rotation makes it possible to choose different operating modes: laminar flow deposition, turbulent flow, with or without vortices. These possibilities contribute to an improved control of the quality of the electro-deposit. In particular, it is advantageous to choose a laminar flow regime in order to benefit from a homogeneous solution and to allow a deposit of chemical element resulting in a layer having few surface asperities. Advantageously, the second electrode is rotated. Rotating the second electrode can be used to homogenize the solution or to place it in a precise hydrodynamic regime, by mixing within the electrolytic solution. Another advantage, in the case where the second electrode is not on the surface of one of the two cylinders, is not to continuously keep the same area of the substrate facing the second electrode. The second electrode therefore rotates advantageously around the closed cylinder but can also rotate around itself, especially when the geometry of the second electrode allows it, thanks to this rotation, to stir the electrolytic solution, for example when the second electrode is on one of the two cylinders. In a particular embodiment, in which the second electrode and the cathode are on cylinders of different substantially parallel axes, the second electrode and the cathode can rotate around each other, in addition to turning around their respective axes in the electrolysis bath.

Advantageously, the method may provide a first cylinder, closed, of the same axis as the second hollow cylinder. This arrangement of the first closed cylinder in the tank formed by the second hollow cylinder makes it possible to promote a hydrodynamics in a laminar regime when one of the cylinders or the two cylinders revolve around their respective common axes.

In some embodiments, it is not necessary to add a second electrode in the vessel. Indeed, it can be expected that the other of the surfaces of the outer surface of the first cylinder and the inner surface of the second cylinder is the second electrode.

This configuration is particularly advantageous in that it allows to benefit from a constant distance between the second electrode and the cathode in the electrolysis bath, at least for the conductive parts facing one another. In this way, the circulation of the cations between the second electrode and the cathode is more homogeneously in the electrolysis bath. In this embodiment, the second electrode is advantageously an anode counter-electrode.

Some deposits can be made by progressive dissolution of a second electrode soluble in the electrolysis bath. For example, it can be a second copper electrode in copper sulphate solution. When a current is applied between the second electrode and the cathode, the deposition of a cation on the substrate causes the release from the second soluble electrode of a copper atom that converts to a cation. In this way, electro-deposition can continue until complete consumption of the second electrode.

The second electrode can therefore preferably be chosen to be of the same nature as the ions in solution because it makes it possible to regenerate the solution permanently, which still allows greater flexibility in the context of an industrial application.

In order to remotely move the closed cylinder carrying the substrate, the method can provide a movable carrying arm connected to the first cylinder, when the flexible substrate is applied to the outer surface of the first cylinder, closed. This support arm may be intended to be rotated about an axis outside the electrolysis bath and a translation parallel to the axis of the first cylinder. It can also be intended to undergo a radial displacement. Using the carrier arm mentioned above, a displacement of the first cylinder from the electrolysis bath of the second cylinder to at least one tank in a third cylinder is possible. In this way, the process can involve several distinct successive deposition steps, which is particularly suitable for industrial processes. By moving the support arm from one tank to another, the process can be enriched with steps other than electro-deposition steps. In particular, the method may include moving the first cylinder to an annealing chamber. The annealing steps are particularly useful for the manufacture of photosensitive devices such as photo voltaic cells. In parallel with the electro-deposition process described above, the invention also relates to the cylindrical geometry reactor implemented during the process.

Thus, the invention also relates to a deposition device, by electrochemistry, of at least one thin layer on a flexible substrate, comprising:

a first closed cylinder arranged inside a second hollow cylinder, a flexible substrate forming a first electrode on one of the outer surface of the first cylinder and the inner surface of the second cylinder,

a second electrode.

This device proposes to use a cylindrical geometry reactor in association with a flexible substrate. This combination makes it possible to benefit from a smaller volume of electrolytic solution for depositing than in a parallelepipedal geometry, and also to deposit in a more homogeneous solution, thanks to the more interesting mixing possibilities of a solution contained between a closed cylinder and a hollow cylinder.

This device also makes it possible to choose two positions for the substrate. The latter can indeed be placed on the outer surface of the closed cylinder or on the inner surface of the hollow cylinder forming the tank containing the electrolysis bath.

Several configurations are envisaged for this device.

It is more particularly possible to have as a second electrode the other of the surfaces of the outer surface of the first cylinder and the inner surface of the second cylinder.

This configuration makes it possible to benefit from a first electrode arranged facing the second electrode, with a constant distance between these two electrodes. This configuration is particularly advantageous in the case where the two electrodes cover the entire surface of the first and second cylinders on which they are respectively placed.

The displacement of the cylinder carrying the substrate can be done remotely in a controlled manner, in particular by means of a support arm connected to the first cylinder. Means for connecting the first cylinder to the support arm can therefore be provided on the first cylinder. When the substrate is not carried by the first closed cylinder, the carrier arm can be used to stir the electrolytic solution by performing a controlled rotation of the cylinder about its axis and possibly by translating the cylinder in the electrolysis bath. Electro-deposition employing the device mentioned above can advantageously involve several steps. Therefore, the invention also relates to an installation comprising a device as described above.

According to one embodiment, such an installation furthermore comprises:

a movable carrying arm, connected to the first closed cylinder, and

at least one annealing chamber.

These elements are particularly suitable for electro-deposition for producing photosensitive cells. Indeed, using the support arm, the substrate advantageously mounted on the closed cylinder, can be moved from one tank to another. Furthermore, it is advantageous to provide a flange forming a lid integral with the support arm to seal the successive tanks of the installation.

The annealing chamber makes it possible to carry out reductive annealing and vapor phase deposition under high temperature, for example greater than 400 ° C.

Advantageously, the support arm may comprise a flange for closing the second cylinder. This flange can form an upper cover closing the various tanks of the installation, such as the electrolysis tanks and the annealing chamber. In this way, it is possible:

- To inject a neutral gas into the tanks, to avoid any oxidation phenomenon,

to avoid the splashing of electrolytic solution towards the outside of the tanks or

isolating the annealing chamber from the rest of the installation in order to avoid exposing the tanks to the high temperatures at which the substrate is exposed in the enclosure. DESCRIPTION OF FIGURES

The method which is the subject of the invention will be better understood on reading the description and on the observation of the following drawings in which: FIG. 1 illustrates an example of an electro-deposition device in cylindrical geometry that may be derived from the process object of the invention; Figure 2 illustrates the four main steps of the electro-deposit method object of the invention; Figure 3a is a schematic perspective representation of a cylindrical electro-deposition installation according to one embodiment; FIG. 3b is a representation in plan view of a cylindrical electro-deposition installation according to the embodiment of FIG. 3a; Figure 4 is a graph showing the volume in liters of electrolyte solution used in parallelepiped and cylindrical electrolysis baths for three different substrate sizes; FIG. 5 illustrates the sixteen steps of a method of manufacturing a photovoltaic panel on a flexible substrate according to a completely wet embodiment.

DETAILED DESCRIPTION

As illustrated in FIG. 1, the invention involves a cylindrical electro-deposition device comprising a substantially cylindrical tank 2 into which a closed cylinder 1 is inserted. As illustrated in FIG. closed 1 comprises, on a portion of its outer surface, a flexible substrate 3. This substrate is connected to a power supply 9 to form a first electrode 8, advantageously forming a cathode. The tank 2 is, as shown in FIG. 1, also connected to the feed 9 to form a second electrode 7, advantageously a counter-electrode or anode 7. A reference electrode 4 serving as an independent potential probe can also be provided in the electrolysis bath between the closed cylinder 1 and the tank 2.

In a first step, the electrolysis bath, delimited by the tank 2, is filled with an electrolytic solution whose concentration C is chosen as a function of particular deposition parameters. The electro-deposition begins with the application of an electric current I or a voltage between the substrate and the reference electrode or a voltage applied between the substrate and the anode generated by the power supply 9 between the anode 7 and the cathode 8. The closed cylinder 1 is then rotated at a pulsation ω, thanks to a motor 5 actuating an arm 6. The pulsation ω will subsequently be designated as the speed of rotation of the closed cylinder 1 about its axis in the vessel 2.

The electro-deposition method of the invention comprises four main steps illustrated in FIG. 2. A first step, SI, consists in placing the flexible substrate 3 on a cylinder. Two scenarios can arise.

In a first embodiment, it is advantageous to place the substrate 3 on the outer surface of the closed cylinder 1. This substrate can be held in place by means of toothed disks 10, or any other means of fixing a flexible substrate on a cylindrical surface, such as, for example, the application of an adhesive, the holding by depressurization under the substrate 3 or the maintenance by a mechanical jaw made of an inert material in chemical solution. The curved surface of the closed cylinder 1 may also be the substrate 3 itself, provided that the latter is watertight and does not allow the electro-lyric solution to penetrate into the closed cylinder 1. When the substrate 3 does not intrinsically part of the closed cylinder 1, the closed cylinder 1 may have an electrically insulating outer surface, in order to avoid electro-deposition on areas outside the substrate 3. In the opposite case, an electrically insulating material may be applied in the zones in question. outside the substrate 3 exposing an electrically conductive surface of the closed cylinder 1.

An alternative embodiment consists in placing the flexible substrate 3 on the inner surface of the tank 2. In this embodiment, the closed cylinder 1 can be electrically conductive and form a second electrode, which can be a counter electrode or anode 7. The closed cylinder 1 may also be at least partially covered with a conductive material to form a second electrode, against an electrode or anode 7. The vessel 2 may advantageously be electrically insulating, or, in the opposite case, the electrically conductive zones. exposed can be covered with an electrically insulating material.

A third alternative may consist of placing the substrate 3 on the outer surface of the closed cylinder 1, and placing in the substantially cylindrical vessel 2 a second substantially cylindrical electrode 7. This second electrode 7 may be a closed cylinder covered at least partially by a conductive element connected to 9. supply 9. These two cylinders can be rotated about their respective axes and move in the tank 2, so as to stir the electrolytic solution during the electroplating process.

Following this first step SI of installation of the flexible substrate 3 on a cylinder, it is appropriate, in step S2, to position the closed cylinder 1 in the hollow cylinder 2. This placement can advantageously be carried out in such a way that the closed cylinder 1 and the tank 2 have substantially the same axis. By placing the closed cylinder 1 in the tank 2 so that these two cylinders have the same axis, it is possible to benefit from a particular hydrodynamics to homogenize the electrolytic solution. The electrolysis bath is advantageously prepared in the next step S3. This preparation comprises the pouring of a liquid solution of electrolyte into the volume located between the closed cylinder 1 and the tank 2. It also comprises the application of electrical contacts connecting the substrate 3 to a power supply 9, and the counter- 7, which may be the tank 2, to the same power supply 9. It is also advantageous to have a reference electrode 4 in the space between the anode 7 and the cathode 8, serving as independent potential probe. The flexible substrate 3, covered with a metal layer, for example molybdenum, can be electrically contacted by means of a copper ribbon. In order to avoid the deposition of elements on this ribbon, its exposed surface may be covered with an electrically insulating material. It is also possible to reverse steps S2 and S3.

According to an advantageous embodiment, the tank 2 is not the second electrode 7, and this second electrode 7 is an electrode that is soluble in the electrolytic solution and consists of the material that it is intended to deposit on the substrate 3.

The actual electro-deposition begins once an electric current I is applied by the supply 9 between the two electrodes 7 and 8, for example between the anode 7 and the cathode 8. This current is delivered to the step S4. With this current, the cations, for example at least one element of the columns 11, 12, 13, 14 or 16, present in the electrolytic solution, migrate from the second electrode, for example the anode 7 to the substrate 3 forming cathode 8. When the counter electrode 7 is soluble, the application of a current progressively dissolves the anode 7 in the electrolysis bath. For example, the anode 7 may be copper, soaking in an electrolytic solution of sulfate or copper nitrate. During the electrolytic deposition, the deposition of copper on the substrate 3 by reducing ions in the solution is accompanied by the dissolution of the same amount of copper from the anode 7. Advantageously, the method comprises an additional step of rotation of the closed cylinder 1 with respect to the hollow cylinder 2. This rotation makes it possible to generate a particular hydrodynamics in the electrolytic solution, such as to homogenize the solution, thereby ensuring a more uniform deposition of the chemical elements on the substrate 3. Furthermore, it is conceivable to rotate the vessel 2 about its axis rather than a rotation of the closed cylinder 1 about its axis. The homogenization effect obtained is equivalent.

The electro-deposition on flexible substrate 3 is thus controlled by three parameters: the cation concentration C in the electrolytic solution, the intensity I of the electric current delivered by the supply 9 or the deposition potential V between the substrate and the reference electrode 4, and the rotational speed ω of the closed cylinder 1 about its axis in the tank 2.

Thanks to a fine dosage of these three parameters, it is possible to guarantee a controlled electrochemical deposition in composition and thickness. Advantageously, the electrochemical deposition is carried out in more than one step to form a complex device, for example a photosensitive panel on flexible substrate 3. The devices involved in the manufacture of such a panel according to the method of the invention are shown in Figures 3a and 3b. The manufacture of such a panel advantageously comprises several successive electro-deposits in the liquid phase. At first, a deposit of copper, indium and gallium can be made. The layer obtained can then advantageously undergo a gas phase reduction annealing in an annealing chamber 201. To do this, it can be provided to move the closed cylinder 1 comprising the flexible substrate 3 with the aid of a carrying arm 60. , intended to undergo a translation along the axis of the cylinder, and a rotation about an axis substantially parallel to that of the closed cylinder 1 and located outside the vessel 2. In this way, it It is possible to install several electrolysis baths in cylindrical tanks 2, 220, 230, advantageously arranged in a circle around the carrying arm 60. The closed cylinder 1 carrying the flexible substrate 3 can then be moved from a bath to the bath. other by translation and rotation of the carrier arm 60. Moreover, the carrier arm 60 can advantageously also move by radial translation, thus allowing with the two modes of displacements mentioned above, to move in the three directions of space .

The reducing annealing step, for example under a hydrogen atmosphere, may be carried out in an annealing chamber 201 in which the flexible substrate 3 undergoes heat treatment by hot gas propulsion, such as that described in patents FR 2975223 and FR Advantageously, the support arm 60 then comprises a flange forming a cover 11 installed above the closed cylinder 1 and able to close the tanks of the electrolysis baths 2, 220, 230, as well as the reducing enclosure 201 Closing the reducing chamber 201 is particularly advantageous because of the presence of hydrogen that can react with the contact with the oxygen present in the air. By closing the tanks 2, 220, 230, it is possible to make a primary vacuum or to inject a neutral gas into the tanks to avoid oxidation of the walls of the electrodes and cylinders not dipping in the electrolytic solution in addition to those dipping in the electrolyte solution.

The reducing annealing step may advantageously be followed by a selenization or sulphurization step carried out in the same vapor phase chamber 201 and at temperatures above 400 ° C.

Subsequently, the device obtained, comprising for example a Cu absorber layer (In, Ga) Se2, undergoes two other deposits in the liquid phase. These deposits may be: a first chemical deposit of cadmium sulphide (CdS), forming a buffer layer, and a second electrolytic deposition of zinc oxide (ZnO), forming a conductive transparent layer corresponding to the upper electrical contact the photosensitive panel, the initial metal layer of the flexible substrate 3, for example molybdenum, forming the rear contact.

In addition to the electro-deposition method, the invention also relates to the electro-deposition device with a cylindrical geometry for a flexible substrate 3. The electro-deposition device with cylindrical geometry makes it possible to achieve substantial savings in the volume of electrolytic solution compared with electro-deposition devices with parallelepipedic geometry. Indeed, the electrolytic solution is included in the volume delimited by the closed cylinder 1 on the one hand and the tank 2 on the other hand. It therefore appears that the cylindrical geometry makes it possible to reduce the quantities of electrolytic liquid used by increasing the size of the closed cylinder 1. The gain in the volume of solution is moreover even greater than the size of the substrate 3, and therefore the outer surface of the closed cylinder 1 is large. FIG. 4 is a graph comparing different electrolysis baths, some with parallelepipedic geometry, the others with a cylindrical geometry, used with 3 different substrate sizes 3: 10 × 10 cm ² , 15 × 15 cm ² and 30 × 60 cm ² . This graph highlights the advantage of using a cylindrical geometry electrochemical device for large surfaces of substrate 3. In fact, to achieve electro-deposition on a substrate 3 whose surface has an area of 30x60 cm ² , the device with cylindrical geometry requires about 55 liters against 200 liters for the bath with parallelepiped geometry. In this example, the cylindrical geometry makes it possible to save about a factor of four over the volume of electrolytic solution used.

The electro-depositing device object of the present invention, for example as shown in Figure 1, advantageously comprises a hollow cylindrical substrate holder, closed at both ends by two toothed disks 10. The electrical contacts connecting the power supply 9 to the cathode substrate 3 8 are conveyed by a hollow shaft 6 advantageously arranged above the closed cylinder 1. The electrical contact of the cathode can thus follow the rotational movement of the substrate 3 without being twisted. It is preferably a rotating electrical contact. Advantageously, the hollow shaft 6 may contain, on the upper part of the closed cylinder 1, a flange forming a cover 11 intended to close the upper end of the tank 2. This makes it possible to avoid evaporation of the solution electrolytic during the phases of electro-deposit, or even to avoid possible splashing that might otherwise occur. Moreover, as described above, the presence of a flange 11 forming a lid makes it possible to seal the tank 2 and to inject a neutral gas therein to limit the insertion into the electrolytic oxygen solution present in the tank. external atmosphere between lid and the solution level. This thus makes it possible to avoid both the oxidation of the immersed parts and the non-immersed parts.

The tanks 2, 220, 230 may comprise openings for injecting continuously, or at selected intervals, an electrolytic solution. In particular, it is possible to provide an inlet opening for introducing an electrolytic solution or a rinsing liquid, and a second opening serving as an outlet for evacuating the electrolytic solution or the rinsing liquid. These openings allow to reuse the same tank to achieve the deposition of different chemical elements, which may require electrolytic solutions of different compositions. The flexible substrate 3 comprises, on its outer surface, a conductive metal which may for example be molybdenum, titanium, aluminum, copper or any other material commonly used to serve as a conductive metal in an electrolysis bath. The electrolytic deposition may advantageously comprise several stages of deposition of different chemical elements. Typically, in the manufacture of photosensitive panels, it is intended to manufacture a stack of thin layers of different materials, for example a stack of layers comprising: copper, indium, gallium, selenium, cadmium sulphide and zinc oxide.

The manufacture of a stack of layers involves more than one step of electro-deposition. Moreover, the deposition of different materials may involve several tanks defining electrolysis baths and annealing enclosures adapted to each material to be deposited. Therefore, the invention also relates to an electro-deposition installation on flexible substrate 3, such as, for example, that shown in Figures 3a and 3b.

As shown in Figure 3a, the closed cylinder 1 is secured to a support arm 60 having an axis of rotation located outside the vessel 2 and substantially parallel to the axis of the first 1 and second 2 cylinders. The attachment of the support arm 60 to the closed cylinder 1 can be done by means of different connecting means, such as, for example, screwing, welding or clipping. As specified above, the carrier arm 60 advantageously has, above the closed cylinder 1, a flange 11 forming a cover for closing the upper ends of the electrolysis vessels 2, 201, 220, 230. The arrangement of the tanks 2, 220, 230 and annealing chamber 201 is advantageously circular, so as to facilitate the movement of the support arm 60 and to reduce the space occupied by the installation.

The carrying arm 60 can rotate about an axis outside the tanks 2, 220, 230, translate along its axis of rotation, and also move radially relative to its axis of rotation. It is therefore possible, with such a carrier arm displacement system 60, to route the substrate 3 at any point of the installation.

The installation as shown in Figures 3a and 3b offers the advantage of considerably reducing the size of an installation for the manufacture of photosensitive devices. For example, to make a panel on a substrate 30x60, 30x120 or 60x120 cm ² , the tank 2 can typically have a radius of 34 cm. Assuming that two electrolysis tanks are installed on the same travel diameter of the carrying arm 60, the size of the two reactors would be almost 70 cm. To give room to the arm 60 and to the operators of the installation, it may be advantageous to take this dimension four times, or about three meters. Such a dimension for the installation makes it possible to envisage the presence of rinsing reactors between the electro-deposition of Cu, In, Ga and the reducing annealing, but also between the deposit of CdS and F electro-deposition of ZnO.

It is also conceivable to configure an electro-deposition device or an installation in horizontal rather than vertical position. Advantageously, it is then possible to stack the tanks one on the other, and to move the carrier arm 60 along a vertical axis to move the substrate 3 from one tank to another. Such a configuration has the advantage of optimizing the floor space by an arrangement in height. Example of realization

Figure 5 illustrates in sixteen steps a particular embodiment of the invention.

In a first step S500, the flexible substrate comprising a coating of 50 μιη of molybdenum thickness is placed on a closed cylinder 1 with a radius of 10 cm and a height of 150 cm. In step S501, a soluble copper anode is introduced into an electrically insulating tank 2 of radius 34 cm and height 150 cm. A reference electrode 4 is also provided in the tank 2.

In step S502, the closed cylinder 1 is introduced into the cylindrical vessel 2, so that the two cylinders have substantially the same axis. Electrical contacts are made to connect a power supply 9 to the flexible substrate 3 on the one hand, to form a cathode 8, and the counter electrode 7 on the other hand to form an anode.

In step S503, an electrolytic solution with a concentration of 0.25 mol / L of sulfuric acid H ₂ SO ₄ and containing 1 mol / l of CuSO ₄ is poured into the tank 2. In step S504, a potential of -1 V relative to the reference potential or a current I of 450 mA is applied between the anode 7 and the cathode 8.

In the next step S505, the closed cylinder 1 is rotated about its axis at a speed of 10 revolutions per minute for 15 minutes.

At the end of this step, the copper present in the solution covers the flexible substrate 3 and a copper layer is thus formed.

Because of the concentration evolution of the copper ion solution, the copper anode 7 is then caused to dissolve and thus obtain a bath in a finely regulated concentration.

It then follows a step S506 rinsing the tank 2. After this rinsing step, a new anode 7 indium is introduced into the electrolysis bath filled with sulfuric acid and indium sulfate at the same time. step S507.

It is then proceeded to an electro-deposit of In as described above, during a step S508.

In a similar manner to that described above, it is proceeded to a rinsing of the tank 2 in step S509, followed by the introduction of a gallium soluble anode 7 in step S510, and an electro deposition of gallium at step S511. Subsequently, the closed cylinder 1 is moved with the aid of the carrying arm 60 to the reducing annealing enclosure 201. In step S512, a reduction annealing is carried out under a high temperature hydrogen atmosphere.

This step is followed by a selenization step S513, under high temperature, in the same chamber 201 as in the previous step.

Then, the closed cylinder 1 is moved to a tank 220 where there is a chemical deposition of CdS in step S514.

Finally, the closed cylinder 1 is moved to an electrolysis tank 230 in which the photosensitive panel is made by electro-depositing a layer of ZnO.

The invention is not limited to the embodiments described above, and may include equivalent embodiments.

For example, it is possible to use substantially cylindrical vessels of non-circular section. It is also possible to vary the electro-deposition parameters during the process, by modifying the intensity I, the potential V, the rotation speed ω and the cation concentration C dynamically.

The arrangement of the various elements of the device and the installation may differ from that presented above, in particular with a view to increasing the ergonomics of the installation. It is also possible to move the substrate 3 by means of a carrier arm 60 movable by translation along the three directions of the space.

It is also conceivable to provide a simultaneous rotation of the tank 2, 220, 230 and the closed cylinder 1, in opposite directions or in the same direction. When the counter-electrode is not the closed cylinder 1 or the tank 2, 220, 230, it is possible to put this counter-electrode 7 in rotation in the electrolysis bath, around the substrate 3 and around its axis .

The filling rate of the tanks can vary from one deposit to another. It is thus possible to fill the tanks only partially with electrolytic solution, or to fill them completely.

Claims

A method of depositing a thin layer on a flexible substrate (3), by electrochemistry, comprising the following steps:

in a bath of electrolysis, providing a closed first cylinder (1) in a hollow second cylinder (2);

- applying the flexible substrate (3) on one of the outer surface of the first cylinder (1) and the inner surface of the second cylinder

(2), said flexible substrate (3) forming a first electrode (8),

- providing, in said electrolysis bath, at least one second electrode (7, 4), and

- applying a potential difference between the first electrode (8) and the second electrode for electro-depositing the thin layer on the flexible substrate

(3).

Method according to claim 1, comprising rotating the first cylinder (1) about its axis during electro-deposition.

Method according to one of the preceding claims, providing for the rotation of the second electrode (7, 4).

Method according to one of the preceding claims, providing a first cylinder (1), closed, of the same axis as the second cylinder (2), hollow.

Method according to one of the preceding claims, wherein the other one of the outer surface of the first cylinder (1) and the inner surface of the second cylinder (2) is the second electrode (7).

Method according to one of claims 1 to 4, providing a second electrode (7) soluble.

7. Method according to one of the preceding claims, wherein the flexible substrate (3) is applied to the outer surface of the first cylinder (1), and there is provided a movable carrier arm (6, 60) connected to the first cylinder. 8. Process according to claim 7, comprising the displacement of the first cylinder

(1) from the electrolysis bath of the second cylinder (2) to at least one tank (201, 220, 230) in a third cylinder.

9. Method according to one of claims 7 or 8, comprising moving the first cylinder (1) to an annealing chamber (201).

Apparatus for deposition, by electrochemistry, of at least one thin layer on a flexible substrate (3), comprising:

- a first cylinder (1), closed, arranged inside a second cylinder (2), hollow,

a flexible substrate (3) forming a first electrode (8) on one of the outer surface of the first cylinder (1) and the inner surface of the second cylinder (2),

a second electrode (7, 4).

11. Device according to claim 10, wherein the other of the surfaces of the outer surface of the first cylinder (1) and the inner surface of the second cylinder (2) is the second electrode (7). 12. Device according to claim 10, wherein the second electrode (7) is soluble.

13. Device according to one of claims 10 to 12, wherein the first cylinder (1) comprises connecting means to a support arm (6, 60).

14. Installation for depositing, by electrochemistry, a stack of thin layers on a flexible substrate (3) comprising a device according to one of claims 10 to 13.

The plant of claim 14, further comprising

a movable carrier arm (60) connected to the first closed cylinder (1) and at least one annealing enclosure (201).

16. Installation according to one of claims 14 and 15, wherein the carrier arm (60) comprises a flange (11) for closing the second cylinder (2).