Method for preparing perovskite structure

Abstract

The invention relates to a method for producing a perovskite structure on a substrate surface, where the perovskite has the general structure of ABX3, where A is at least partially an organic compound, and where the method uses a source of organic compounds free of halide ions. Improved photovoltaic properties of the resulting perovskite are obtained, and the method allows large-scale production.

Description

Technical Field

[0001] The present invention relates to a method and a device for preparing a perovskite structure on a substrate, the perovskite structure having the general structure ABX3, wherein A is at least partially an organic compound, wherein the method and the device use two different sources of organic compounds. The method and the device can be used to prepare solar cells. Background Art

[0002] Perovskite semiconductor thin films are most commonly fabricated using solution-based methods. Solar cells made from such perovskite materials have achieved high efficiencies, but solution-based methods present some particular difficulties that make them less suitable for industrial use. One difficulty is the difficulty of scaling up to large-area, high-throughput processes required for large-scale production, and other difficulties are related to the use of solvents. The solvent must be removed, while residues may remain, potentially causing electrically active defects, either from impurities or from the formation of internal surfaces related to porosity. One thin film deposition method that has been proven in the large-scale production of semiconductor thin films is vacuum evaporation. Vacuum evaporation is truly additive in nature and can obtain films of very high purity. On the other hand, vacuum evaporation of multi-component thin films requires very precise control of the vapor fluxes of the different components.

[0003] The composition of the most commonly used perovskite material for solar cells can be written as ABX3. A, B, and X will occupy specific lattice positions in the perovskite crystal structure. A is usually an organic molecule such as methylammonium (MA) or formamidine. (FA) or a mixture of the two, or a mixture of an organic molecule and Cs. Other elements are possible, but Cs is the one most commonly used. In all perovskites that have produced high efficiency (>20%) solar cells to date, B is Pb. X is I or a mixture of I and Br, and may also be Cl. Therefore, many high-performance perovskites have the general formula (MA,FA,Cs)Pb(I,Br)3.

[0004] When such films are prepared by evaporation, a typical evaporation source set would be a The one with iodide (FAI), the one with PbI2 (lead iodide) and the one with CsBr (cesium bromide). Optionally, there may also be a source with methylammonium iodide (MAI).

[0005] However, there remains a need for more efficient and better controlled methods to enable scale-up of the manufacturing process to large-scale production. Summary of the invention

[0006] The present invention aims to overcome the disadvantages of the prior art by providing a method and apparatus for preparing perovskite films, which are advantageous for both controlled structure formation and large-scale production.

[0007] In a first aspect, the invention relates to a method according to claim 1 .

[0008] In a second aspect, the invention relates to a device for preparing a perovskite structure (10) on a substrate surface (11), wherein the perovskite has a general structure of ABX3, wherein component A is an organic molecule or a mixture of organic molecules, or wherein A is cesium, potassium and / or rubidium or a mixture of organic molecules with cesium, potassium and / or rubidium, component B is lead and / or tin, and component X is a halide ion,

[0009] and wherein the apparatus comprises a vacuum chamber (12), the vacuum chamber (12) comprising a substrate inlet (14) and a substrate outlet (16);

[0010] wherein the vacuum chamber comprises at least one deposition zone (18) in which at least a first evaporation source (20) and a second evaporation source (22) of a component are arranged, wherein the first evaporation source (20) comprises component AX and the second evaporation source (22) comprises component BX;

[0011] A third source is provided, wherein the third source is a third evaporation source (24) containing component A as a salt, which is provided in the deposition zone (18) or in an evaporation reactor (26) which is connected to the deposition zone vapor of the vacuum chamber, or wherein the third source is an external source (28) containing a gas containing component A, which is connected to the deposition zone vapor, and wherein the salt contains the organic molecule or a mixture of organic molecules as a cation and wherein the anion is not a halide ion, and wherein the gas contained in the external source (28) contains formamidine, formamidine Methylammonium or methylamine; and

[0012] wherein the vacuum chamber (12) and the optional evaporation reactor (26) comprise heating means (29) configured to each heat an evaporation source under reduced pressure to evaporate a component and generate a flow of the component, and wherein the vacuum chamber is configured to bring the flow into contact with the substrate surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Process pressure for different deposition times, with or without FAAc (formamidine acetate) supply during the co-evaporation process (triangle or circle data points, respectively).

[0014] Figure 2 .Perovskite solar cell device (A = 0.126cm 2) is determined by IV measurements performed under standard test conditions using a class AAA solar simulator.

[0015] Figure 3 . Schematic diagram of a device according to the invention. Dashed lines indicate communication. DETAILED DESCRIPTION

[0016] Implementation plan for each item

[0017] A non-limiting list of embodiments is disclosed below.

[0018] In one embodiment of any aspect of the invention, the components AX and BX of the first and second evaporation sources, respectively, are solid when heated, preferably in the form of a powder.

[0019] In one embodiment of any aspect of the present invention, the component AX of the first evaporation source is selected from formamidine Iodide, Formamidine Bromide, Formamidine chloride, methylammonium iodide, methylammonium bromide or methylammonium chloride or a combination of two or more thereof.

[0020] In one embodiment of any aspect of the present invention, the component BX of the second evaporation source is selected from lead iodide (PbI2), lead bromide (PbBr2) or lead chloride (PbCl2) or a combination of two or more thereof, or is selected from tin iodide (SnI2 or SnI4), tin bromide (SnBr2 or SnBr4) or tin chloride (SnCl2 or SnCl4) or a combination of two or more thereof.

[0021] In one embodiment of any aspect of the invention, a third evaporation source is provided and comprises component A as a salt, wherein the anion is selected from acetate, formate, tetrafluoroborate, hexafluorophosphate and thiocyanate, and wherein the salt is preferably selected from formamidine acetate or methylammonium acetate or a combination thereof, and wherein the salt is preferably in the form of a powder.

[0022] In one embodiment of any aspect of the invention, an external source containing a gas comprising component A is provided, and wherein the gas is purified before entering the deposition zone.

[0023] In one embodiment of any aspect of the invention, the invention comprises providing a fourth evaporation source, wherein the fourth evaporation source comprises a component AX, wherein A is cesium, potassium and / or rubidium, wherein AX is preferably selected from cesium acetate, cesium formate, cesium iodide (CsI) and cesium bromide (CsBr), and evaporating the component of the fourth evaporation source under reduced pressure by heating the fourth evaporation source to produce a flow of the component and contacting the flow of the evaporated component with the surface of the substrate in the deposition zone and allowing the component to form a perovskite structure on the surface.

[0024] In one embodiment, component A is selected from formamidine, formamidine Methylammonium and / or methylamine.

[0025] In one embodiment of any aspect of the invention, the reduced pressure in the deposition zone is less than 1 x 10 -4 mbar.

[0026] In one embodiment of any aspect of the invention, the substrate has a multi-layer structure including preferred layers such as a transparent conductive oxide (TCO) and a hole or electron transport layer.

[0027] In one embodiment of any aspect of the invention, the third evaporation source is arranged in an evaporation reactor in vapor connection with the deposition zone; and wherein the method preferably comprises the step of purifying the flow of the evaporated component from the third evaporation source before entering the deposition zone.

[0028] In one embodiment of any aspect of the invention, the flow of the components is monitored using at least one suitable detector arranged in the deposition zone, preferably by using one or more quartz crystal rate detectors or mass spectrometry.

[0029] In one embodiment of any aspect of the invention, at least components of the first, second and preferably also the third evaporation source are co-evaporated.

[0030] In one embodiment of any aspect of the invention, the temperature of the substrate is lower than the temperature of the components in the flow.

[0031] In one embodiment of any aspect of the invention, the vacuum chamber or apparatus is configured so that one or more substrates can automatically enter and leave the vacuum chamber via a substrate inlet (14) and a substrate outlet (16), respectively. This can be achieved by a conveyor belt on which the substrates are placed and which continuously moves through the chamber.

[0032] Suitably, the inlet and outlet of the vacuum chamber are arranged to seal the chamber to maintain the internal vacuum thereof, which may be achieved using suitable vacuum locks and / or valves.

[0033] In one embodiment of the second aspect of the present invention, the device is configured to achieve online continuous production of perovskite structures on the substrate surface by enabling the substrate to enter the vacuum chamber via the substrate entrance and transfer from the entrance via the deposition area to the substrate exit to leave the vacuum chamber. This can be achieved by a vacuum lock. When the lock is opened, the substrate is moved into the lock, after which the valve leading to the atmosphere is closed, the lock is evacuated to a vacuum state, and then the valve leading to the process vacuum chamber is opened and the substrate is transported to the process chamber. When the process chamber is closed, the substrate is accelerated to a certain translation speed, at which the actual deposition process is performed. The acceleration is controlled to allow the substrate to catch up with the previous substrate, thereby forming a series of substrates that travel through the actual deposition area of ​​the online process equipment without interrupting the deposition process, so as to achieve high productivity. After deposition, the substrates are locked outside the process vacuum chamber one by one by a reverse locking sequence.

[0034] In one embodiment of the second aspect of the present invention, the third evaporation source (24) is arranged in the evaporation reactor (26), and wherein the apparatus preferably comprises a purification device (30) configured to purify the evaporated components from the third evaporation source before entering the deposition zone.

[0035] In one embodiment of any aspect of the invention, an external source (28) containing a gas comprising component A is arranged in vapor connection with the deposition zone, and wherein the apparatus preferably comprises a purification device (31) configured to purify the gas before entering the deposition zone.

[0036] In one embodiment of the second aspect of the present invention, the device further comprises at least one detector (32) and a control unit (34) operably connected to the at least one detector (32), wherein the at least one detector (32) is configured to detect or measure at least one property of the device and transmit a signal representing the at least one property to the control unit (34), and wherein the control unit (34) is configured to control at least one of a heating device (29), a pressure device (36) or a flow control device for the evaporation reactor (26) or an external source (28).

[0037] In one embodiment of the second aspect of the invention, the apparatus comprises a detector (32), wherein the detector (32) is a quartz crystal rate detector.

[0038] Unless stated otherwise, all embodiments are combinable.

[0039] Detailed Description

[0040] method

[0041] The method according to the present invention aims to prepare a perovskite structure or a perovskite structured film on a substrate surface, wherein the perovskite has a general structure of ABX3. Component A is selected from organic molecules, or mixtures of organic molecules, cesium, potassium and / or rubidium, and mixtures of organic molecules with cesium, potassium and / or rubidium. In one embodiment, A is a mixture of organic molecules and cesium. When component A is an organic molecule, it is preferably formamidine, formamidine methylammonium and / or methylamine. Component B is lead and / or tin, and X is a halide ion, preferably an iodide ion and / or a bromide ion. In one embodiment, the perovskite structure has A 1- x Cs x Pb y I 2-x+y Br x The structure of , wherein x is 0.30 ± 0.05, y is 1.1 ± 0.1, and A is formamidine The thickness of the perovskite film on the substrate is preferably in the range of 0.1-2.0 μm, more preferably 0.2-1.0 μm.

[0042] Perovskite structure or perovskite film is prepared by vapor deposition of components on the substrate surface, and wherein the substrate is arranged in a deposition zone in a vacuum chamber. Provide at least one first evaporation source and at least one second evaporation source, which respectively contain components AX and BX, and the first and second evaporation sources are preferably arranged in a deposition zone. In one embodiment, at least two first evaporation sources are provided, i.e., the main first evaporation source and the secondary first evaporation source. In another embodiment, at least two second evaporation sources are provided, i.e., the main second evaporation source and the secondary second evaporation source. The substrate can be installed or arranged horizontally above the evaporation source or vertically installed or arranged next to the evaporation source. The components of the first and second evaporation sources are preferably solid, and preferably in the form of powder, which is beneficial because it will avoid the use of solvents. An additional source (third source) of component A as an organic molecule or a mixture of organic molecules is also provided, and in one embodiment, the third source is a third evaporation source comprising component A as a salt, wherein the salt comprises an organic molecule or a mixture of organic molecules as a cation, and wherein the anion is not a halide ion. By using a salt of A in which the anion is not a halide ion (such as iodide or bromide), the organic component can be provided without also providing additional halide ions, which may interfere with or hinder the formation of the desired perovskite structure and composition. A non-limiting list of preferred anions is acetate, formate, tetrafluoroborate, hexafluorophosphate and thiocyanate. The third evaporation source is preferably arranged in the deposition zone or in an evaporation reactor connected to the deposition zone vapor. In another embodiment, the third source is an external source from which component A is provided to the deposition zone as a gas, wherein the gas comprises component A, and wherein component A is formamidine, formamidine, Methylammonium and / or methylamine. The advantage of component A using an external gas source is that the organic compound can be provided without also providing additional halide ions, and in addition, the gas can be purified before entering the deposition zone, thereby obtaining better structural control and better photovoltaic properties of the perovskite layer. A fourth evaporation source can also be provided in the deposition zone or in an evaporation reactor, wherein the fourth evaporation source comprises component A as a cation, wherein A is cesium, potassium and / or rubidium, and wherein anions are preferably selected from acetate, formate, iodide and bromide. In a preferred embodiment, the fourth evaporation source comprises cesium acetate, cesium formate, cesium iodide (CsI) and / or cesium bromide (CsBr). The evaporation of the components of the fourth evaporation source is carried out under reduced pressure and preferably by heating as described above.

[0043] The streams of components A, B and X are provided by heating at least the first, second and optionally the third evaporation source under reduced pressure to evaporate the components from the evaporation source and / or by providing a gas stream of component A from an external source. The heating of the evaporation sources is performed individually in order to better control the composition of the stream of the evaporated component. In one embodiment, the first, second and third evaporation sources are heated individually at a temperature of 20-300° C., preferably 50-200° C. In one embodiment, the third evaporation source is heated at a temperature of 20-150° C., preferably 50-100° C. In one embodiment, the third evaporation source is arranged in an evaporation reactor and wherein the third evaporation source is not heated during evaporation. The reduced pressure during evaporation is preferably less than 5x10 -4 mbar, preferably below 1x10 - 4 mbar, but preferably not less than 1x10 -5 mbar.

[0044] The flow of the component is then brought into contact with the substrate surface in the deposition zone, thereby allowing the component to form a perovskite structure on the surface. The components of the first and second evaporation sources are preferably co-evaporated, and preferably the components of the third evaporation source are also co-evaporated. The flow of the component is adjusted by adjusting the heating temperature of the evaporation source and the flow from the external source or evaporation reactor to obtain the desired structure and composition on the substrate surface. The flow rate or deposition rate is preferably monitored using at least one suitable detector arranged in the deposition zone, and the detector is preferably one or more quartz crystal rate detectors or mass spectrometry. The control unit communicates with the detector and also communicates with the heating device of the evaporation source, preferably also with the pressure device that adjusts the pressure in the vacuum chamber. In one embodiment, before deposition on the substrate surface, the flow rate or deposition rate is monitored, and when a stable or preferred or predetermined flow rate or deposition rate has been reached, the flow of the component is brought into contact with the substrate surface for deposition. Then, the substrate having a perovskite structure obtained can be further processed according to the use of the substrate. In a preferred embodiment, the perovskite structure obtained is annealed, preferably at a temperature of 30-150°C, more preferably at a temperature of 40-120°C.

[0045] In a preferred embodiment, the component AX of the at least one first evaporation source is selected from formamidine Iodide, Formamidine Bromide, Formamidine Chloride, methylammonium iodide, methylammonium bromide or methylammonium chloride or a combination of two or more thereof. In another preferred embodiment, the component BX of the at least one second evaporation source is selected from lead iodide (PbI2), lead bromide (PbBr2) or lead chloride (PbCl2) or a combination of two or more thereof, or tin iodide (SnI2 or SnI4), tin bromide (SnBr2 or SnBr4) or tin chloride (SnCl2 or SnCl4) or a combination of two or more thereof. In yet another preferred embodiment, the third evaporation source is provided and comprises component A as a salt, wherein component A is a cation, and an anion is selected from acetate, formate, tetrafluoroborate, hexafluorophosphate and thiocyanate. Preferably, the salt is selected from formamidine acetate or methylammonium acetate or a combination thereof, and wherein the salt is preferably in the form of a powder. In one embodiment, the third evaporation source is arranged in an evaporation reactor connected to the deposition zone vapor, and the method preferably includes a step of purifying the flow of the evaporated component from the third evaporation source before entering the deposition zone. An advantage of having the third evaporation source in an external evaporation reactor is that the flow rate or deposition rate of components A, B and X can be more easily adjusted individually by adjusting evaporation parameters such as temperature and pressure. In one embodiment, the gas from the external source or from the evaporation reactor is provided at an overpressure relative to the desired perovskite structure, facilitating better control.

[0046] In one embodiment, the component X of the perovskite structure is a mixture of at least two halide ions, preferably iodide ion and bromide ion, and the component AX of the first evaporation source is preferably formamidine bromide or methylammonium bromide, and the component BX of the second evaporation source is preferably PbI2. In another embodiment, the component A of the perovskite structure is a mixture of an organic molecule and one of cesium, potassium or rubidium, preferably cesium. Preferably, a fourth evaporation source is provided, wherein the fourth evaporation source comprises component A, and wherein the component A is an organic molecule or a mixture of organic molecules or a mixture of organic molecules with cesium, potassium and / or rubidium, with the proviso that component A is different from component A of the first evaporation source. In one embodiment, component A of the fourth evaporation source is cesium, preferably CsBr, cesium acetate or cesium formate, and wherein the first evaporation source preferably comprises an organic molecule, preferably formamidine Iodide, Formamidine Bromide, Formamidine Chloride, methylammonium iodide, methylammonium bromide or methylammonium chloride. The fourth evaporation source can be arranged in the deposition zone or in an evaporation reactor connected to the deposition zone vapor. The fourth evaporation source can be a part of the first or second evaporation source or mixed with the first or second evaporation source.

[0047] The substrate may be any suitable substrate, preferably made of a silicon wafer, a metal or polymer foil or glass. The substrate is preferably coated with a multilayer structure, including layers such as a transparent conductive oxide (TCO) and a hole or electron transport layer. During the method, the substrate may be heated or cooled using any suitable means to allow the components to condense onto the surface and / or react on the surface and form a perovskite. In one embodiment, the temperature of the substrate is lower than the temperature of the evaporated components to promote condensation of the components. In one embodiment, the temperature of the substrate is 20-40°C. In one embodiment, the method is part of a process for preparing a photovoltaic component.

[0048] In order to describe the present method and its advantages, the preparation of a non-limiting perovskite having the structure of FAPbI3 will be disclosed. This structure can be prepared by FAI (formamidine) according to the prior art method. The film is prepared by vacuum evaporation of FAI (iodide) and PbI2. If these two components evaporate consistently at the same molecular rate, the resulting film will ideally have the desired composition. However, it is difficult to control FAI evaporation because FA dissociates and byproducts interfere with the process and lead to an increase in process pressure, which will limit the deposition rate due to the dispersion of evaporated molecules and atoms. The adhesion or deposition of the dissociated components may be different, and all components of FAI may not be incorporated into the film in the same proportion, resulting in non-stoichiometric perovskite materials. In addition, CVD-like reactions may occur, further complicating the growth of perovskite films. Another complicating factor is that the iodine from FAI evaporates in the form of corrosive and toxic hydrogen iodide. All of these vapor components may have different adhesion or deposition properties on the growing film, so it will be difficult to control the composition of the perovskite material, especially because there is a dependency between the amount of FA and I leaving the FAI source. The present invention solves these problems by using an additional source of organic molecules that do not contain any other constituents of the perovskite structure. In this specific non-limiting example, formamidine can be used Acetate as formamidine evaporation source (the third evaporation source).

[0049] Formamidine by evaporation Acetate can be used to convert formamidine into molecules are added to the process. Thus, the formamidine added to the growing film can be balanced and the amount of iodine, and in this way the desired perovskite composition is obtained.

[0050] With all formamidine supplied from FAI source Compared with formamidine Evaporation of acetate has additional advantages. First, formamidine is more The vapor pressure of formamidine above acetate is relatively high, and it can evaporate at a lower temperature. The dissociation degree of the molecule, and the background pressure of the undesirable molecule can be kept low. For a given formamidine flux, high vapor pressure is also conducive to a relatively small evaporation surface. A convenient arrangement of this property is utilized as an external evaporation reactor or an external source, from which the formamidine vapor is transported to the deposition zone in a pipe. Another advantage of an external source or evaporation reactor is that the vapor can be purified before being discharged into the deposition zone, thereby reducing the level of impurities and undesirable molecules or atomic components in the described district and in the resulting structure.

[0051] Using the present method, a perovskite structure can be produced online on a substrate surface, which will then facilitate large-scale production. In one embodiment, the substrate enters the vacuum chamber via a substrate inlet and is transferred from the inlet via a deposition zone for depositing perovskites according to the present invention to a substrate outlet to leave the vacuum chamber, and wherein the transfer is performed automatically.

[0052] As shown in the examples and Figure 1 and 2 As shown in , the present invention facilitates higher deposition rates and thus faster production without compromising the quality of the resulting perovskite layer.

[0053] equipment

[0054] According to the present invention, the device (10) is suitable for preparing a perovskite structure or a perovskite structured film as described above on a substrate surface (11) arranged in a vacuum chamber (12) in the device. A substrate inlet (14) and a substrate outlet (16) are arranged in the vacuum chamber (12), which are respectively configured to allow the substrate to enter and leave the vacuum chamber, and the substrate inlet and outlet are preferably equipped with suitable closing devices, such as vacuum load locks. The vacuum chamber (12) comprises at least one deposition zone (18), in which at least one first evaporation source (20), at least one second evaporation source (22) and optionally a third evaporation source (24) are arranged. The first evaporation source (20) comprises a component AX, the second evaporation source (22) comprises a component BX, and the third evaporation source comprises a component A of the perovskite structure. The third evaporation source (24) can be arranged in an evaporation reactor (26) connected to the vapor of the deposition zone (18), or the component A is a gas provided in an external source (28), wherein the external source is connected to the vapor of the deposition zone.

[0055] The vacuum chamber (12) is configured to allow a substrate to enter via a substrate inlet (14) and is arranged in a deposition zone (18) in a manner such that a flow of components from an evaporation source, an evaporation reactor and an external source contacts the substrate surface, and wherein the vacuum chamber (12) is configured to allow the substrate to exit via a substrate outlet (16). A pressure device (36) is arranged in the apparatus, configured to generate and regulate pressure in the vacuum chamber (12) and in the evaporation reactor (26), and the pressure device is preferably any suitable pump, such as a vacuum pump.

[0056] An advantage of the present invention is that it allows online continuous production of perovskite. This can be achieved by allowing the substrate to automatically enter the vacuum chamber via the substrate inlet and transfer from the inlet to the substrate outlet via the deposition area for depositing perovskite to leave the vacuum chamber. Preferably, the substrate inlet and the substrate outlet have a suitable closing device, preferably a vacuum load lock. In a preferred embodiment, the at least one first evaporation source, at least one second evaporation source, the third evaporation source or the evaporation reactor comprising the third evaporation source, or an external source are arranged along the transfer path of the substrate. Using an evaporation reactor comprising the third evaporation source or an external source comprising component A as a gas is beneficial to online production because it requires less space in the deposition area compared to a solid evaporation source, and allows higher flexibility in terms of flow composition and flow optimization.

[0057] In order to evaporate the components from the first, second and third evaporation sources, the vacuum chamber (12) and the optional evaporation reactor (26) comprise heating means (29) configured to heat the sources respectively, and the pressure means (36) are configured to reduce the pressure in the vacuum chamber (12) and in the optional evaporation reactor (26). Using the evaporation reactor (26) to evaporate the third evaporation source (24) or using an external source (28) for the gaseous component A has the following advantages: the flow of the component can be purified before entering the vacuum chamber and the deposition zone. When the third evaporation source (24) is arranged in the evaporation reactor (26), the device preferably comprises a purification device (30) configured to purify the evaporated component from the third evaporation source before entering the deposition zone. When an external source (28) containing the component A as a gas connected to the deposition zone (18) is provided, the device preferably comprises a purification device (31) configured to purify the gas before entering the deposition zone. The purification device (30) or (31) is preferably any suitable filter. Non-limiting examples of purification devices are membrane gas separation devices and selective gas capture materials.

[0058] Depending on the composition of the evaporation source, the amount of heat required to evaporate the components under reduced pressure may vary. The heating of the evaporation sources is preferably performed individually, i.e. each evaporation source is heated individually, and the heating device (29) may be any suitable heating device, such as an electric heater. The pressure device (36) is appropriately arranged to generate and maintain reduced pressure in the vacuum chamber and in the optional evaporation reactor (26).

[0059] The device (10) further comprises at least one detector (32), which is suitably arranged in the vacuum chamber (12) and is configured to measure or detect at least one property of the device. The property is suitably temperature, pressure, composition of evaporated components in the vacuum chamber (12) or a property of a perovskite structure formed on a substrate. In some embodiments, a plurality of detectors (32) are arranged in the vacuum chamber (12) and they may be configured to measure or detect the same property or different parameters. The device (10) further suitably comprises a control unit (34), which is operably connected to the at least one detector (32) so that a signal can be transmitted from the at least one detector (32) to the control unit (34), and optionally also from the control unit (34) to the at least one detector (32).

[0060] In addition, the control unit (34) comprises a processing circuit which is suitably configured to control at least one property of the apparatus (10). In some embodiments, this is achieved by the control unit (34) being configured to control the heating device (29). In other embodiments, the control unit (34) may also be configured or alternatively configured to control the supply of a third source or external source (28) from the evaporation reactor (26) by operating a flow control device (not shown) such as a control valve or the like, thereby controlling the flow of the third source or external source. Additionally or alternatively, the control unit (34) may be configured to control the pressure in the vacuum chamber (12) by, for example, operating a pressure device (36).

[0061] Thus, the control unit (34) is used to monitor at least one property in the vacuum chamber (12) and is also used to control at least one property by operating any or all of the heating means, the vacuum pump and the supply of the third source. This has the advantage that the conditions within the vacuum chamber (12) can be controlled so as to achieve the desired quality of the produced perovskite.

[0062] Non-limiting suitable detectors are quartz crystal rate detectors and mass detectors such as mass spectrometers. The quartz crystal rate detectors are preferably arranged so that each detector detects only the flow from one evaporation source. When an external source or evaporation reactor is used, a mass spectrometer is preferably used. By monitoring the composition of the flow over time, the structure of the perovskite can be controlled, especially in an online production where the evaporation source, evaporation reactor and external source are arranged along the transfer path of the substrate.

[0063] The vacuum chamber (12) is preferably further configured to anneal the obtained perovskite structure on the substrate surface. In one embodiment, the vacuum chamber is configured to heat the obtained perovskite structure to a temperature of 30-150°C.

[0064] Example

[0065] Example 1

[0066] Through PbI2, CsBr and formamidine Thermal co-evaporation of iodide (FAI) (both in powder form) deposited a layer of FA on a NiO-coated glass substrate. 1-x Cs x Pb y I 2-x+y Br x (x=0.30±0.05, y=1.1±0.1) thin film perovskite solar cell absorber layer, the obtained film thickness is 0.6±0.1 μm. Optionally providing formamidine Additional supply of acetate (FAAc) as formamidine An additional source of 20% was added to compensate for the formamidine lost by decomposition. All film depositions were performed as follows. The estimated evaporation temperatures were: PbI2 ~ 300 °C, CsBr ~ 450 °C, FAI ~ 150 °C, FAAc ~ 80 °C.

[0067] This process is <2×10 -6 For deposition using FAAc, 1 × 10 -5 mbar FAAc partial pressure, the external source consisted of a stainless steel bottle heated to 80 ± 5 ° C. The gas inlet port was not facing the substrate.

[0068] The evaporation of PbI2, CsBr and FAI was started by gradually increasing the power of the heater around the source crucible, which was located below the substrate and in the line of sight of the substrate. The evaporation rate was stabilized for 25 minutes, during which the substrate shutter remained closed. The evaporation rate of each component and therefore also the film composition was controlled by means of quadrupole mass spectrometry feedback. After the evaporation rate was stabilized, the substrate shutter was opened and the film deposition was started. The deposition rate was adjusted to obtain a film thickness of 0.6±0.1μm within a deposition time of 12, 20, 30, 40 or 60 minutes. The substrate shutter was then closed and the source heater was turned off. After the perovskite was deposited, the composition was determined by X-ray fluorescence and / or by depositing C60 / In2O x :Zn transparent electron selective contacts are further processed into solar cell devices.

[0069] Due to the fact that the evaporated species (both desired and undesired dissociation products) form a background pressure in the vacuum chamber, the process pressure is higher for processes with higher deposition rates. Figure 1 , which shows the process pressure measured for different deposition times. Each data point corresponds to one deposition. More importantly, Figure 1 The effect of adding FAAc is also shown. Without FAAc supply, the process pressure measured for a 60 minute process was about 2 to 4 × 10-5 mbar. By supplying 1×10 -5 mbar of FAAc can significantly increase deposition rates while maintaining (or reducing) process pressure.

[0070] Reducing the deposition time from 30 minutes to 12 minutes by increasing the deposition rate does not necessarily reduce the power conversion efficiency (PCE) of the solar cell device. Figure 2 and are shown in Table 1, which include PCE values ​​measured under standard testing conditions for a solar cell device fabricated using a perovskite absorber layer deposited in the process, using a sputtered transparent conductive oxide as the top electrode, and an evaporated C60 buffer layer in between.

[0071] Table 1. Solar cell IV measurement data for solar cells fabricated using the described perovskite deposition process (FAAc addition).

[0072]

Claims

1. A method for preparing a perovskite structure on a substrate surface, wherein the perovskite has a general structure of ABX3, wherein component A is an organic molecule or a mixture of organic molecules, or wherein A is cesium, potassium and / or rubidium or a mixture of organic molecules with cesium, potassium and / or rubidium, component B is lead and / or tin, and component X is a halide ion, and wherein the method comprises the following steps: a. providing the substrate in a deposition zone in a vacuum chamber; b. providing at least a first evaporation source and a second evaporation source of said component, wherein said first evaporation source comprises component AX and said second evaporation source comprises component BX, and wherein a third source is provided, wherein said third source is a third evaporation source comprising component A as a salt or wherein said third source is an external source containing a gas comprising component A, wherein said salt comprises said organic molecule or a mixture of organic molecules as a cation and wherein the anion is not a halide ion, and wherein said gas contained in said external source comprises formamidine, formamidine Methylammonium or methylamine; c. by evaporating the components by heating the first evaporation source and the second evaporation source under reduced pressure, and by evaporating component A from the third evaporation source under the reduced pressure or by providing the gas flow from the external source to provide a gas phase flow of components A, B and X; d. contacting the flows of the components A, B and X with the substrate surface in the deposition zone and allowing the components to form a perovskite structure on the surface. 2 . The method according to claim 1 , wherein the components AX and BX of the first evaporation source and the second evaporation source are respectively solid when heated, preferably in the form of powder.

3. The method according to claim 1 or 2, wherein the component AX of the first evaporation source is selected from formamidine Iodide, Formamidine Bromide, Formamidine chloride, methylammonium iodide, methylammonium bromide or methylammonium chloride or a combination of two or more thereof.

4. The method according to any one of claims 1 to 3, wherein the component BX of the second evaporation source is selected from lead iodide (PbI2), lead bromide (PbBr2) or lead chloride (PbCl2) or a combination of two or more thereof, or is selected from tin iodide (SnI2 or SnI4), tin bromide (SnBr2 or SnBr4) or tin chloride (SnCl2 or SnCl4) or a combination of two or more thereof.

5. The method according to any one of the preceding claims, wherein the third evaporation source is provided and comprises component A as a salt, wherein the anion is selected from acetate, formate, tetrafluoroborate, hexafluorophosphate and thiocyanate, and wherein the salt is preferably selected from formamidine acetate or methylammonium acetate or a combination thereof, and wherein the salt is preferably in the form of a powder.

6. The method according to any one of claims 1 to 4, wherein an external source containing a gas comprising component A is provided, and wherein the gas is purified before entering the deposition zone.

7. The method according to any one of the preceding claims, wherein the method further comprises providing a fourth evaporation source, wherein the fourth evaporation source comprises component A as cation, wherein A is cesium, potassium and / or rubidium, and wherein anions are preferably selected from acetate, formate, iodide and bromide, preferably wherein the fourth evaporation source is selected from cesium acetate, cesium formate, cesium iodide (CsI) and cesium bromide (CsBr), and evaporating a component of the fourth evaporation source under the reduced pressure by heating the fourth evaporation source to produce a flow of the component, and contacting the flow of the evaporated component with the substrate surface in the deposition zone and allowing the component to form a perovskite structure on the surface.

8. The method according to any one of the preceding claims, wherein the reduced pressure in the deposition zone is less than 1 x 10 - 4 mbar.

9. The method according to any of the preceding claims, wherein the substrate has a multilayer structure comprising preferred layers such as a transparent conductive oxide (TCO) and a hole or electron transport layer.

10. The method according to any one of the preceding claims, wherein the third evaporation source is arranged in an evaporation reactor in vapor connection with the deposition zone; and wherein the method preferably comprises a step of purifying the flow of evaporated components from the third evaporation source before entering the deposition zone.

11. A device for preparing a perovskite structure (10) on a substrate surface (11), wherein the perovskite has a general structure of ABX3, wherein component A is an organic molecule or a mixture of organic molecules, or wherein A is cesium, potassium and / or rubidium or a mixture of organic molecules with cesium, potassium and / or rubidium, component B is lead and / or tin, and component X is a halide ion, and wherein the apparatus comprises a vacuum chamber (12), the vacuum chamber (12) comprising a substrate inlet (14) and a substrate outlet (16); wherein the vacuum chamber comprises at least one deposition zone (18) in which at least a first evaporation source (20) and a second evaporation source (22) of a component are arranged, wherein the first evaporation source (20) comprises component AX and the second evaporation source (22) comprises component BX; A third source is provided, wherein the third source is a third evaporation source (24) containing component A as a salt, which is provided in the deposition zone (18) or in an evaporation reactor (26) which is connected to the deposition zone vapor of the vacuum chamber, or wherein the third source is an external source (28) containing a gas containing component A, which is connected to the deposition zone vapor, and wherein the salt contains the organic molecule or a mixture of organic molecules as a cation and wherein the anion is not a halide ion, and wherein the gas contained in the external source (28) contains formamidine, formamidine Methylammonium or methylamine; and wherein the vacuum chamber (12) and the optional evaporation reactor (26) comprise heating means (29) configured to each heat an evaporation source under reduced pressure to evaporate a component and generate a flow of the component, and wherein the vacuum chamber is configured to bring the flow into contact with the substrate surface.

12. The apparatus according to claim 11, wherein the apparatus is configured to enable one or more substrates to automatically enter and leave the vacuum chamber via the substrate inlet (14) and the substrate outlet (16), respectively.

13. The apparatus according to claim 11 or 12, wherein the apparatus is configured for in-line continuous production of perovskite structures on a substrate surface.

14. The apparatus according to any one of claims 11 to 13, wherein the third evaporation source (24) is arranged in an evaporation reactor (26), and wherein the apparatus preferably comprises a purification device (30) configured to purify the evaporated components from the third evaporation source before entering the deposition zone.

15. An apparatus according to claim 11, wherein an external source (28) containing a gas containing component A is arranged in vapor connection with the deposition zone, and wherein the apparatus preferably comprises a purification device (31) configured to purify the gas before entering the deposition zone.

16. The apparatus according to any one of claims 11 to 15, further comprising at least one detector (32) and a control unit (34) operably connected to the at least one detector (32), wherein the at least one detector (32) is configured to detect or measure at least one property of the apparatus and transmit a signal representing the at least one property to the control unit (34), and wherein the control unit (34) is configured to control at least one of a heating device (29), a pressure device (36) or a flow control device for the evaporation reactor (26) or an external source (28).

17. The apparatus of claim 16, wherein the detector (32) is a quartz crystal microbalance rate sensor.

18. A method according to any one of claims 1 to 10, wherein the flow of the components is monitored using at least one suitable detector arranged in the deposition zone, preferably by using one or more quartz crystal rate detectors or mass spectrometry.

19. The method according to any one of claims 1 to 10, wherein at least components of the first evaporation source, the second evaporation source and preferably also the third evaporation source are co-evaporated.

20. The method of any one of claims 1 to 10, wherein the temperature of the substrate is lower than the temperature of components of the flow.

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