DE102021116272A1 - Process for producing a crystallized perovskite layer - Google Patents

Abstract

The invention relates to a method for producing a crystallized perovskite layer, at least comprising the steps: i) applying a perovskite precursor to a substrate, so that a perovskite precursor layer is produced on the substrate andii) generating a negative pressure over the perovskite precursor layer, wherein at the same time a process gas is flowed over the perovskite precursor layer for negative pressure, so that a crystallized perovskite layer forms.

Description

The invention relates to a method for producing a perovskite layer, in particular for optoelectronic applications such as solar cells and solar modules, LEDs and photodetectors.

The main challenge for mass production of metal halide perovskite (MHP) solar cell technology is to develop reliable and scalable methods to fabricate homogeneous, hole-free (i.e., continuous) and large-area perovskite layers from a solution-based, perovskite-containing perovskite precursor. The perovskite-containing perovskite precursor is usually initially in dissolved form.

The finished, nucleated (i.e. crystallized) perovskite layer, with the general empirical formula ABX3, has methylammonium (MA), cesium (Cs) and/or formamidinium (FA) as component A, for example, while component B is often given by lead (Pb). is. X is, for example, iodine (I), bromine (Br) and/or chlorine (Cl) or a mixture of these elements.

In this context, a large number of solution-based coating and printing techniques, such as slot die coating, blade coating, blade coating, spray coating and last but not least inkjet printing, have shown their potential for the production of large-area solar cells and other optoelectronic devices in recent years applications proven.

Various methods have been established for the crystallization of solution-based perovskite films, e.g. B. Radiation annealing and crystallization at elevated temperature, anti-solvent quenching, gas quenching and vacuum drying. While anti-solvent quenching is primarily used in spin coating processes, gas quenching and vacuum drying are common as in-line or post-deposition drying steps in scalable coating and printing processes. In the considered processes, the perovskite precursor is printed on different types of substrates, and in particular on layers.

Vacuum drying in particular has been established for inkjet printed layers. It is the most common method for manufacturing highly efficient solar modules or solar cells by crystallizing the wet film at an ambient pressure between 0.01 and 100 mbar. Based on these efforts, efficiencies of almost 20% for partially inkjet printed solar modules and solar cells [1,2] and more than 17% for fully inkjet printed solar modules and solar cells [3] have been achieved. However, perovskite precursor layers produced by means of spin coating, slot die coating, blade coating, blade coating or spray coating can also be treated by vacuum drying.

As such, the vacuum drying process can be explained by the LaMer crystallization and nucleation theory: rapid solvent evaporation under vacuum conditions results in a supersaturated film with high nucleation density from which the perovskite crystals grow more homogeneously compared to a slower drying film with fewer nuclei and irregular growth conditions without vacuum assistance .

Proceeding from this, the present invention is based on the object of providing a method which is improved with regard to the methods known in the prior art described above and in particular with regard to the homogeneity of crystallized perovskite layers which can be achieved.

This object is achieved by a method having the features of claim 1, use of the method according to claim 13, and a system having the features of claim 14.

Advantageous refinements of these aspects of the invention are specified in the corresponding dependent claims and are described below.

• i) Aufbringen eines flüssigen Perowskit-Präkursors auf ein Substrat, so dass eine insbesondere flüssige oder semi-flüssige Perowskit-Präkursorschicht auf dem Substrat erzeugt wird,
• ii) Erzeugen eines Unterdrucks über der Perowskit-Präkursorschicht, wobei gleichzeitig zum Unterdruck ein Prozessgas über die Perowskit-Präkursorschicht geströmt wird, sodass sich aus der Perowskit-Präkursorschicht eine kristallisierte Perowskitschicht auf dem Substrat bildet.

According to claim 1, a method for producing a crystallized perovskite layer from a perovskite precursor is disclosed, comprising the following steps:

• i) application of a liquid perovskite precursor to a substrate, so that an in particular liquid or semi-liquid perovskite precursor layer is produced on the substrate,
• ii) generating a negative pressure over the perovskite precursor layer, a process gas being flowed over the perovskite precursor layer at the same time as the negative pressure, so that a crystallized perovskite layer forms on the substrate from the perovskite precursor layer.

The gas flow of the process gas flowing over the perovskite precursor layer leads to an advantageously accelerated and increased homogeneous nucleation within the perovskite precursor layer, as a result of which a crystallized perovskite layer that is significantly improved compared to the prior art is formed.

The use of this novel gas flow-assisted vacuum drying process enables the production of regular, optically dense and hole-free perovskite layers and in particular MHP layers with a photoconversion efficiency (PCE) of 16%.

In a first step i) of the method according to the invention, the liquid perovskite precursor containing perovskite is first applied to a substrate, in particular printed, in order to produce a perovskite precursor layer there. The application, in particular the printing, can be done by a variety of methods, such as ink jet printing, spin coating, slot die coating, blade coating, blade coating or spray coating. Inkjet printing in particular has proven to be advantageous for the method according to the invention. The following is used as a substrate, for example: self-assembled monolayers (SAMs), transparent, conductive oxide (transparent conductive oxides, TCOs), metal or glass.

The perovskite precursor is preferably present in dissolved form in a liquid. The presence of a liquid present next to the precursors that form the perovskite to be crystallized for dissolving (solvent) the precursors causes the response of the system as a liquid. This also includes a state in which the liquid for dissolving the precursors (solvent) is reduced to such an extent, eg in the step of application to a substrate, that the perovskite precursor is only present as viscous or as semi-liquid. For this purpose, the perwoskite precursor has a perovskite portion and a solvent portion. The perovskite content can be described here with the molecular formula ABX3, containing as component A, for example, methylammonium (MA), cesium (Cs) and/or formamidinium (FA), while component B is often lead (Pb). X is, for example, iodine (I), bromine (Br) and/or chlorine (Cl) or a mixture of these elements. Preferably, Cs _0.05 (FA _0.83 MA _0.17 ) _0.95 Pb(I _0.83 Br _0.17 ) ₃ is used. The perovskite precursor also contains one or more solvents such as dimethylformamide, dimethyl sulfoxide and/or γ-butyrolactone as a solvent component. In particular, the combined use of the three solvents mentioned here has proven to be advantageous. However, acetonitrile, 2-methoxyethanol, N-methyl-2-pyrrolidone can also be used as solvents for the perovskite precursor.

In the second step ii) according to the invention, a negative pressure is generated above the perovskite precursor layer on the substrate, with a gas flow simultaneously flowing over the perovskite precursor layer, so that a crystallized perovskite layer forms on the substrate from the perovskite precursor layer. During the second step ii) according to the invention, the negative pressure remains essentially constant, i.e. a dynamic equilibrium arises, with essentially the same amount of gas being supplied per unit of time as is being discharged.

d.h. bar*s/l ergibt.The fact that is essential for the invention that a gas flow is present at the same time as an existing negative pressure is not described in the prior art, to the applicant's knowledge. In order to describe this special state with physical quantities, the pressure, here the negative pressure in bar, must be combined with a gas flow in volume per unit of time, ie liters per second -l/s-, in particular in relation to what a unit of bar per l/s $\left(\frac{ba\mathrm{right}}{\raisebox{1ex}{$l$}\!\left/ \!\raisebox{-1ex}{$s$}\right.}\right),$

ie bar*s/l results.

This form of vacuum drying with a simultaneous gas flow over the perovskite precursor layer significantly accelerates the crystallization of the perovskite precursor layer compared to conventional vacuum drying methods and improves the homogeneity of the forming perovskite layer. In this context, a homogeneous layer is a perovskite layer that is as continuous laterally as possible, ie, hole-free, and has as high a purity as possible, ie, with as little as possible Foreign atoms and vacancies and with the most constant possible strength, ie constant vertical extension, ie layer thickness.

Steps i) and ii) of the method according to the invention do not have to be carried out in succession but can also be carried out simultaneously.

According to one embodiment of the invention, the gas flow generated simultaneously with a negative pressure over the perovskite precursor layer can be realized by simultaneous pumping out and flooding of a vacuum chamber. For this purpose, the substrate with the perovskite precursor layer is preferably first introduced into a vacuum chamber and this is then closed in an airtight or vacuum-tight manner.

A vacuum chamber used for the method according to the invention is preferably designed to be partially evacuated in order to generate a negative pressure, while simultaneously generating a gas flow with a process gas directed over the surface of the substrate with the perovskite precursor layer. Furthermore, the vacuum chamber is ideally designed to accommodate, i.e. to receive, a substrate with the perovskite precursor printed thereon. For this purpose, the vacuum chamber can have a receptacle designed to receive the substrate with the perovskite precursor layer. Ideally, the vacuum chamber can also be closed in an airtight or vacuum-tight manner, so that it can be pumped out when the substrate with the perovskite precursor printed on it is inserted, without the resulting pressure difference between the interior of the vacuum chamber and the environment causing ambient air to flow into the vacuum chamber from the outside.

At the beginning of pumping down, the vacuum chamber can be filled with gas, for example air, corresponding to the atmospheric pressure of the environment, for example at an absolute pressure of about one atmosphere (1 bar). Depending on the size of the vacuum chamber and the pump used, pumping the vacuum chamber down to a few mbar usually takes a few seconds. Therefore, according to one embodiment, the vacuum chamber can first be sufficiently evacuated before carrying out the second step ii) of the method according to the invention by pumping out the air before the gas flow is generated by subsequent simultaneous flooding of the vacuum chamber. However, starting from a vacuum chamber filled with gas or air (e.g. at an internal pressure of the vacuum chamber of 1 bar), pumping and simultaneous flooding with the process gas can be started directly, with the gas or the air in the vacuum chamber passing through the Gas flow is successively discharged from the vacuum chamber.

The gas flow is preferably implemented in such a way that the vacuum chamber has at least one extraction opening and at least one inlet opening, according to one embodiment, the vacuum chamber being connected through the at least one extraction opening via a pump line to a pump which is designed to pump gas by pumping it out to create a negative pressure (i.e. an absolute pressure below 1 bar) from the vacuum chamber within the vacuum chamber. The at least one outlet opening and the at least one inlet opening of the vacuum chamber are preferably arranged in pairs opposite one another and approximately at the level of the receptacle for the substrate with the perovskite precursor layer. As a result, a gas flow directed from the at least one inlet opening via the perovskite precursor layer to the at least one outlet opening is achieved, which promotes crystallization.

Furthermore, according to one embodiment, the vacuum chamber is connected by at least one inlet opening via a gas line to a gas reservoir, which ideally contains gas with an overpressure relative to the vacuum chamber and in particular to the pump line. It is thus achieved that, according to the invention, a gas flow directed over the surface of the substrate with the perovskite precursor layer is generated, in this embodiment a process gas from the gas reservoir through the gas line via the vacuum chamber and in particular over the surface of the substrate with the perovskite precursor layer through the Pump line is routed to the pump. Finally, the pump releases the pumped process gas to the atmosphere, for example.

The process gas can in particular have N ₂ or consist of N ₂ , but other gases and gas mixtures (eg argon, helium, oxygen, air) can also be used.

In addition, one embodiment provides that the pump line and the gas line each have a valve which is designed to be partially and/or fully opened and/or closed to control the gas flow. For example, with an at least partially open valve on the gas line, a stronger or weaker gas flow in the vacuum chamber can be achieved by partially opening or closing the valve on the pump line. Analog can at least one partially open valve on the pump line, a stronger or weaker gas flow in the vacuum chamber can be achieved by partially opening or closing the valve on the gas line.

A pressure sensor for displaying and/or transmitting the internal pressure of the vacuum chamber is advantageously arranged between the two valves.

The negative pressure above the perovskite precursor layer, i.e. the internal pressure of the vacuum chamber during the second step of the method according to the invention, is preferably between 0.01 and 100 mbar, in particular between 10 and 30 mbar.

Furthermore, the negative pressure above the perovskite precursor layer, i.e. the internal pressure of the vacuum chamber with simultaneous pumping out and flooding of the vacuum chamber during the second step of the method according to the invention, is in a dynamic equilibrium, in particular for a period of 10 s - 300 s, ideally for at least 60 s maintained and thus the gas flow maintained over the surface of the substrate with the perovskite precursor layer. This ensures that the nucleation optimized in the context of the method according to the invention with regard to vacuum drying is actually achieved and optimally completed.

During the second step according to the invention, the gas flow is in particular in a range of 0.01 l/s-0.43 l/s, in particular 0.05 l/s to 0.15 l/s and particularly advantageously at 0.1 I/s.

According to one embodiment of the invention, the negative pressure above the perovskite precursor layer, i.e. the internal pressure p in bar of the vacuum chamber and the gas flow F in l/s (through the vacuum chamber) during the second step ii) according to the invention are at least temporarily in a ratio x=p /F, where x is in the range from 1 mbar*s/l to 230 mbar*s/l.

According to one embodiment, the method is completed by annealing the perovskite precursor layer or the crystallized perovskite layer. For this purpose, the perovskite precursor layer or the crystallized perovskite layer is heated to a temperature that is higher than the process temperature of the vacuum drying, any solvent residues evaporating at least partially. This leads to a further improved purity of the crystallized perovskite layer and thus to increased efficiency in an optional later optoelectronic application, for example as a solar cell and solar module, LED or photodetector.

According to one embodiment of the invention, the annealing can take place via an optional heating device arranged in the vacuum chamber, which is designed to heat the substrate with the perovskite precursor layer or the crystallized perovskite layer. For this purpose, the heating device can be in thermal contact with the receptacle of the vacuum chamber in order to heat the perovskite precursor layer or the crystallized perovskite layer on the substrate within the vacuum chamber. Tempering can also be carried out under the conditions described above, i.e. in particular with the internal pressure prevailing in the vacuum chamber during the second step of the method according to the invention and/or optionally with continuous pumping and flooding of the vacuum chamber, i.e. with a continuous gas flow. Alternatively, the annealing can also be carried out at a higher or lower pressure and at a higher or lower gas flow, in which case the desired pressure can optionally be set before the annealing process by at least partially opening or closing the valves to the gas reservoir or to the pump. Furthermore, the vacuum chamber for the annealing can also be largely evacuated, so that the annealing process takes place at a lower pressure, which facilitates the evaporation of residual solvents.

In a further embodiment, the annealing can also be carried out with a separate heating device, it also being possible to use similar or different process gases and similar or different vacuum conditions than those used in the second step according to the invention.

Furthermore, in an additional embodiment, the annealing can be carried out in a second chamber which is arranged within the vacuum chamber and can optionally be closed in a vacuum-tight manner, the substrate being introduced into this second chamber after the second step of the method according to the invention, e.g. is shifted to carry out the annealing there.

Another aspect of the present invention is that the perovskite precursor layer or in particular the forming crystallized perovskite layer preferably during the second step according to the invention, ie during the crystallization of the perovskite precursor layer, by a measuring device for measuring the homogeneity of the forming crystallized perovskite layer and/or monitored to detect defects within the forming crystallized perovskite layer.

According to one embodiment, an optical spectrometer, in particular a photoluminescence (PL) spectrometer, can be used for this purpose. In order to record corresponding spectroscopic measurements, the vacuum chamber can also have a transparent window, via which the optical measurements on the perovskite precursor layer and in particular on the forming, crystallized perovskite layer are carried out. However, the spectrometer can also be installed completely or partially in the vacuum chamber, so that the measurements do not have to be carried out through a window in the vacuum chamber. In the case of PL spectroscopy, wavelengths in the range from 340 nm to 1020 nm are preferably used.

Furthermore, according to one embodiment, at least during the second step according to the invention, i.e. during the crystallization of the perovskite precursor layer, images of the forming, crystallized perovskite layer can be taken via a window of the vacuum chamber using at least one microscope. The at least one microscope can be an optical microscope, but also an electron microscope, for example. If at least two microscopes are used, both optical and electron microscopes can be used. Likewise, the at least one microscope can be arranged inside the vacuum chamber, so that the recordings do not have to be taken through a window of the vacuum chamber.

A further aspect of the invention consists in the implementation of the method according to the invention by means of a system, the system comprising a vacuum chamber which has a holder designed to hold a substrate with a perovskite precursor layer or a perovskite layer to be formed. The receptacle is optionally thermally connected to a heating element, the heating element being designed to heat the substrate with the perovskite precursor layer or the perovskite layer to be formed, in order to heat the perovskite precursor layer or the perovskite layer. An upper side of the vacuum chamber can additionally have a transparent window, so that the substrate with the perovskite precursor layer or the perovskite layer to be formed, arranged as intended on the receptacle of the vacuum chamber, can be observed through the window. Preferably, at least one inlet opening connected to a gas reservoir and at least one outlet opening connected to a pump designed for pumping out the vacuum chamber are arranged opposite the vacuum chamber at the level of the receptacle, so that the gas flow between the at least one outlet opening and the at least one inlet opening via the intended the substrate arranged in the receptacle of the vacuum chamber with the perovskite layer to be formed or the perovskite precursor layer flows. A valve is preferably arranged between the at least one inlet opening and the gas reservoir and the at least one outlet opening and the pump, which valve can be at least partially opened or closed in order to control the gas flow. A pressure sensor for displaying and/or forwarding an internal pressure of the vacuum chamber is also ideally arranged between the two valves.

In addition, the system includes a spectrometer, which is designed to carry out spectroscopic measurements of the perovskite precursor layer or the perovskite layer that is being formed, at least during the vacuum drying and/or during the annealing.

In addition, the system includes at least one microscope which is designed to take pictures of the forming perovskite layer at least during vacuum drying and/or during tempering.

Furthermore, the system contains a computing unit, having a processor, which is connected to the pressure sensor, the spectrometer and the microscope for exchanging commands and data.

A further aspect of the present invention relates to a system having the features described above.

A further aspect of the present invention relates to an optoelectronic device or an optoelectronic module, wherein the optoelectronic device or the optoelectronic module is produced by the method according to the invention or by a method according to at least one corresponding embodiment.

A further aspect of the present invention relates to a solar cell or a solar module, wherein the solar cell or the solar module is produced by the method according to the invention or by a method according to at least one corresponding embodiment.

A further aspect of the present invention relates to an LED, the LED being produced by the method according to the invention or by a method according to at least one corresponding embodiment.

A further aspect of the present invention relates to a photodetector, the photodetector being produced by the method according to the invention or by a method according to at least one corresponding embodiment.

A further aspect of the present invention relates to a thin-film transistor, the thin-film transistor being produced by the method according to the invention or by a method according to at least one corresponding embodiment.

A further aspect of the present invention relates to a memristor, the memristor being produced by the method according to the invention or by a method according to at least one corresponding embodiment.

A further aspect of the present invention relates to an optically pumped laser, the optically pumped laser being produced by the method according to the invention or by a method according to at least one corresponding embodiment.

• Verfahren zum Tintenstrahldrucken von Perowskitschichten, das mindestens die folgenden Schritte umfasst:
  • - Bereitstellen einer Kammer die dazu eingerichtet ist, evakuiert zu werden und die Mittel aufweist, um einen gerichteten Gasstrom in der Kammer zu erzeugen;
  • - Bereitstellen eines Tintenstrahldruckers für einen Perowskit-Präkursor;
  • - Bereitstellen eines Substrats;
  • - Tintenstrahldrucken einer Perowskit-Präkursorschicht auf das Substrat;
  • - Überführen des Substrats mit der Perowskit-Präkursorschicht in die Kammer;
  • - Evakuieren der Kammer bei gleichzeitigem Strömen von Gas über eine Oberfläche der Perowskit-Präkursorschicht, bis diese getrocknet ist, und anschließend

The method according to the invention can also be described as follows:

• A method for inkjet printing perovskite layers, comprising at least the following steps:
  • - providing a chamber adapted to be evacuated and having means to generate a directed gas flow in the chamber;
  • - providing an inkjet printer for a perovskite precursor;
  • - providing a substrate;
  • - inkjet printing a perovskite precursor layer onto the substrate;
  • - transferring the substrate with the perovskite precursor layer into the chamber;
  • - evacuating the chamber while flowing gas over a surface of the perovskite precursor layer until it dries, and then

Completing the formation of a perovskite layer by annealing or tempering.

• 1 Eine zur Durchführung des erfindungsgemäßen Verfahrens ausgebildete Vakuumkammer, wobei die Vakuumkammer durch eine Pumpleitung an eine Pumpe und durch eine Gasleitung an ein Gasreservoir angeschlossen ist.
• 2 Eine Ausführungsform einer Vakuumkammer zur Durchführung des erfindungsgemäßen Verfahrens, wobei eine Perowskit-Präkursorschicht bzw. eine Perowskitschicht durch ein Fenster der Vakuumkammer sichtbar ist.
• 3 Einen Schnitt durch die Vakuumkammer aus 2, wobei eine Perowskit-Präkursorschicht bzw. eine Perowskitschicht auf einer Aufnahme der Vakuumkammer sichtbar ist.
• 4 Eine über der Aufnahme der Vakuumkammer angeordnete Düse, welche dazu ausgebildet ist, einen auf die Perowskit-Präkursorschicht bzw. die Perowskitschicht gerichteten Gasfluss auszuüben.
• 5 Simulierte Gasflüsse oberhalb der Aufnahme der Vakuumkammer, insbesondere am bestimmungsgemäßen Ort der Perowskit-Präkursorschicht bzw. der Perowskitschicht (hier nicht gezeigt) im Zentrum der Aufnahme, wobei der Gasfluss innerhalb der Vakuumkammer aus 2 und 3 (oben) sowie innerhalb der Düse (mittig) und außerhalb der Düse (unten) aus 4, wobei helle Flächen für einen hohen Gasfluss und dunkle Flächen für einen geringen Gasfluss indikativ sind.
• 6 Ein System zur Durchführung des erfindungsgemäßen Verfahrens, aufweisend unter anderem eine Vakuumkammer, ein Mikroskop, ein Spektrometer sowie eine Recheneinheit.
• 7 Ein Schema des erfindungsgemäßen Verfahrens im Vergleich zum herkömmlichen Vakuumtrocknen, wobei ein gedruckter Perowskit-Präkursor zu einer Perowskitschicht prozessiert wird.
• 8 Gemessene Photolumineszenz (PL)-Intensitäten als Funktion der Wellenlänge während eines herkömmlichen Vakuumtrocknungsprozesses (oben) im Vergleich zum erfindungsgemäßen Verfahren (links unten), wobei helle und dunkle Flächen für ein hohes bzw. geringes PL-Signal indikativ sind. Weiterhin sind die Wellenlängen der Maxima des Fluoreszenzsignals beider Prozesse bzw. Verfahren gezeigt (unten rechts).
• 9 Aufnahmen eines optischen Mikroskops, wobei die Perowskit-Präkursorschicht bzw. die Perowskitschicht an fünf entsprechend markierten Zeitpunkten während der Fluoreszenzsmessungen aus 8 gezeigt sind.
• 10 Röntgenbeugungsmessungen an mittels verschiedener Prozesse, insbesondere mittels des erfindungsgemäßen Verfahrens hergestellten Perowskitschichten (links) sowie elektronenmikroskopische Aufnahmen der entsprechenden Perowskitschichten (rechts).
• 11 Einen elektronenmikroskopischen Querschnitt einer Solarzelle oder Teil eines Solarmoduls mit p-i-n-Architektur, enthaltend eine nach dem erfindungsgemäßen Verfahren hergestellte Perowskitschicht.
• 12 Stromdichte-Spannungs-Kennlinien von mittels verschiedener Prozesse, insbesondere mittels des erfindungsgemäßen Verfahrens hergestellten Solarzellen bzw. Solarmodulen, aufweisend eine Perowskitschicht.

Exemplary embodiments and further features and advantages of the invention are to be explained below with reference to the figures. Show it:

• 1 A vacuum chamber designed for carrying out the method according to the invention, the vacuum chamber being connected to a pump by a pump line and to a gas reservoir by a gas line.
• 2 An embodiment of a vacuum chamber for carrying out the method according to the invention, with a perovskite precursor layer or a perovskite layer being visible through a window of the vacuum chamber.
• 3 A cut through the vacuum chamber 2 , wherein a perovskite precursor layer or a perovskite layer is visible on a photograph of the vacuum chamber.
• 4 A nozzle positioned above the vacuum chamber receptacle configured to impart a gas flow directed toward the perovskite precursor layer or the perovskite layer.
• 5 Simulated gas flows above the recording of the vacuum chamber, in particular at the intended location of the perovskite precursor layer or the perovskite layer (not shown here) in the center of the recording, with the gas flow inside the vacuum chamber from 2 and 3 (top) as well as inside the nozzle (middle) and outside the nozzle (bottom). 4 , where light areas are indicative of high gas flow and dark areas are indicative of low gas flow.
• 6 A system for carrying out the method according to the invention, having, among other things, a vacuum chamber, a microscope, a spectrometer and a computing unit.
• 7 A scheme of the inventive method compared to conventional vacuum drying, wherein a printed perovskite precursor is processed into a perovskite layer.
• 8th Measured photoluminescence (PL) intensities as a function of wavelength during a conventional vacuum drying process (top) compared to the inventive method (bottom left), with light and dark areas indicative of high and low PL signal, respectively. Furthermore, the wavelengths of the maxima of the fluorescence signal of both processes or methods are shown (bottom right).
• 9 Optical microscope images showing the perovskite precursor layer and the perovskite layer at five correspondingly marked time points during the fluorescence measurements 8th are shown.
• 10 X-ray diffraction measurements on perovskite layers (left) produced by means of various processes, in particular by means of the method according to the invention, as well as electron micrographs of the corresponding perovskite layers (right).
• 11 An electron microscopic cross section of a solar cell or part of a solar module with pin architecture, containing a perovskite layer produced according to the method according to the invention.
• 12 Current density-voltage characteristics of solar cells or solar modules produced by means of various processes, in particular by means of the method according to the invention, having a perovskite layer.

1 shows an arrangement for carrying out the method according to the invention, a perovskite precursor layer 11 or a perovskite layer 10 being arranged in a vacuum chamber 14 . In the embodiment shown here, the perovskite precursor layer 11 or the perovskite layer 10 can be observed through a window 25 of the vacuum chamber 14 . The vacuum chamber 14 can, as in 1 shown, also be arranged in a glove box 31 .

At least during step ii) of the method according to the invention, but optionally also when tempering the perovskite precursor layer 11 or the perovskite layer 10 is carried out simultaneously or later, images of the (forming) perovskite layer 10 can be taken via the window 25 using at least one microscope 27 . The at least one microscope 27 can be an optical microscope, but also an electron microscope, for example, and both optical and electron microscopes can also be used in combination. In this case, the at least one microscope 27 can also be located inside the vacuum chamber 14 so that the perovskite precursor layer 11 or the perovskite layer 10 does not have to be observed through a window 25 of the vacuum chamber 14 .

Via the window 25, spectroscopic measurements of the perovskite precursor layer 11 or of the forming perovskite layer 10 are made in order to monitor the perovskite precursor layer 11 or the forming perovskite layer 10 with regard to its homogeneity. A PL spectrometer, for example, can be used as the spectrometer, with the measured PL signal or the measured PL intensity being indicative of the progress and the purity of the crystal growth. In addition, the wavelength of the PL signal allows conclusions to be drawn about the (average) size of the crystallized structures, with smaller or larger wavelengths indicating smaller or larger crystallized structures. Furthermore, larger and/or purer crystals have a higher PL signal. In particular, pure crystals are characterized by a narrow PL signal with a small FWHM as a function of the process parameter under consideration characterized. The change in the PL wavelength, in particular the wavelength of the PL peak as the process progresses, provides information on the dynamics of the crystal growth.

Wavelengths in the range of 340-1020 nm, in particular 470 nm, are preferably used to excite the PL.

In the 1 The vacuum chamber 14 shown is also preferably connected to a pump 17 through at least one extraction opening 15 via a pump line 16, the pump 17 being designed to generate a negative pressure in the vacuum chamber 14 by pumping out gas. In addition, the vacuum chamber 14 is ideally connected to a gas reservoir 20 via at least one inlet opening 18 via a gas line 19 . Preferably, the pump line 16 and the gas line 19 each have a valve 21, 22 which can be opened or closed at least partially. Thus, with the pump 17 running, process gas can flow in a gas flow 13 from the gas reservoir 20 over the vacuum chamber 14 and in particular over the perovskite precursor layer 11 or the forming perovskite layer 10 in order to carry out the method according to the invention. The negative pressure within the vacuum chamber 14 and the strength of the gas flow 13 can be adjusted via the valves 21,22. In order to measure the internal pressure, the system 28 can also have a pressure sensor 23 which is preferably arranged between the two valves 21 , 22 . The pressure can be displayed directly on the pressure gauge, for example, or it can be forwarded to a computing unit 29 . The pressure in the vacuum chamber 14 is preferably between 0.01 mbar and 100 mbar, in particular 10 mbar to 30 mbar. The gas flow 13 through the vacuum chamber 14 is preferably between 0.01 l/s and 0.43 l/s, in particular 0.05 l/s to 0.15 l/s and particularly advantageously 0.1 l/s. The internal pressure of the vacuum chamber 14 -p in bar- and the gas flow 13 -F in l/s- through the vacuum chamber 14 are advantageously in a ratio x=p/F in the range from 1 mbar*s/l to 230 mbar* s/l before.

2 shows a perspective view of an embodiment of a vacuum chamber 14 for carrying out the method according to the invention. The perovskite precursor layer 11 or the forming perovskite layer 10 can be seen through the window 25 .

Furthermore, the embodiment of the vacuum chamber 14 shown here has two extraction openings 15 and inlet openings 18, which are ideally connected to a pump 17 or a gas reservoir 20 in order to, according to the invention, in the case of a negative pressure in the vacuum chamber 14, a via the perovskite precursor layer 11 or the forming perovskite layer 10 directed gas flow 13 to generate. The gas flow 13 can be directed parallel or at an angle over the perovskite precursor layer 11 or the perovskite layer 10 that is being formed. An underside of the vacuum chamber 14 can be designed as a heating element 26 in order to heat or anneal the perovskite precursor layer 11 or the perovskite layer 10 that is being formed. This tempering can be carried out during and/or after step ii) of the method according to the invention, with any solvent residues in the perovskite layer 10 being formed partially evaporating, as a result of which the purity and homogeneity of the perovskite layer 10 are improved. Alternatively, the perovskite precursor layer 11 or the perovskite layer 10 that forms can also be removed from the vacuum chamber 14 after step ii) and annealed on a separate heating element 26 .

3 shows a section through the vacuum chamber 14 from 2 . Here, a receptacle 24 of the vacuum chamber 14 arranged on the optional heating element 26 is visible, on which preferably the perovskite precursor layer 11 or the perovskite layer 10 forming for carrying out the method according to the invention is positioned. Also visible are the optional window 25 of the vacuum chamber 14, as well as the at least one extraction opening 15 and the at least one inlet opening 18.

4 shows a side view of the receptacle 24 of the vacuum chamber 14, a nozzle 30 preferably running between two inlet openings 18 being visible on the receptacle 24. The nozzle 30 preferably has a hood-shaped middle section 40 arranged over the perovskite precursor layer 11 or over the forming perovskite layer 10, wherein the hood-shaped middle section 40 is open to the perovskite precursor layer 11 or to the forming perovskite layer 10, so that a gas flow 13 is directed by the nozzle 30 onto the perovskite precursor layer 11 or onto the perovskite layer 10 which is being formed. The process gas can exit the vacuum chamber 14 via the at least one extraction opening 15 (not shown here). This arrangement further improves the alignment of the gas flow 13 to the perovskite precursor layer 11 or to the perovskite layer 10 that is being formed.

5 shows simulations of the gas flow 13 above the receptacle 24 of the vacuum chamber 14, in particular for the vacuum chamber 14 2 and 3 ( 5 , above). Light and dark areas indicate a strong or weak gas flow 13 . It can be clearly seen how the process gas flows in a gas flow 13 from the two inlet openings 15 here towards the center of the receptacle 24 . Ideally, for the method according to the invention, the perovskite precursor layer 11 or the forming perovskite layer 10 is placed in the center of the receptacle 24 (in 5 not visible). The process gas can exit the vacuum chamber 14 again via the two extraction openings 15 here. In the embodiment shown here, the two inlet openings 18 are arranged at an angle of 90° to one another in relation to the center or center point (ie the intended location of the perovskite precursor layer 11 or the perovskite layer 10) of the circular receptacle 24 of the vacuum chamber 14. Furthermore, in this embodiment, the two discharge openings 15 are also arranged at an angle of 90° with respect to this center or this middle point to one another and in particular to the two inlet openings 18 . This uniform arrangement of the two inlet openings 18 and outlet openings 15 is as in 5 As can be seen, a gas flow 13 directed towards the center or towards the midpoint (ie the intended location of the perovskite precursor layer 11 or the perovskite layer 10) of the circular receptacle 24 is reached. According to one embodiment, only one or more than two withdrawal openings 15 and inlet openings 18 can be used. In addition, the at least one extraction opening 15 or the at least one inlet opening 18 can be arranged anywhere on the walls of the vacuum chamber 14 in order to adapt the gas flow 13 and in particular the direction of the gas flow accordingly. The discharge openings 15 and inlet openings 18 are ideally circular in shape, but they can also be shaped differently, for example oval, in order to adapt the profile of the gas flow 13 accordingly. Furthermore, the profile and/or the strength of the gas flow 13 can be influenced by the size of the exhaust openings 15 and inlet openings 18, whereby, for example, in the case of circular exhaust openings 15 and/or inlet openings 18, smaller or larger radii of the outlet openings 15 and/or inlet openings 18 ensure a smaller or larger gas flow 13 . Optionally, the extraction openings 15 and inlet openings 18 can also be designed to be at least partially closed or opened in order to adjust the gas flow 13 variably with regard to its profile and its strength.

Furthermore are in 5 simulated gas flows 13 for a vacuum chamber 14 with a as in 4 illustrated nozzle 30 shown. The central figure shows the gas flow 13 within the nozzle 30 and in particular in the area of the hood-shaped central section 40 arranged above the perovskite precursor layer 11 or above the forming perovskite layer 10, and the lower figure shows the corresponding gas flow 13 on the receptacle 24 It can be seen that the gas flow 13 is directed or concentrated through the nozzle 30 onto the intended area of the perovskite precursor layer 11 or the forming perovskite layer 10, which promotes the crystallization of the perovskite precursor layer 11 or the forming perovskite layer 10 in the method according to the invention becomes. The process gas can exit the vacuum chamber 14 again via the at least one extraction opening 15 .

6 shows a system 28 for carrying out the method according to the invention. The system 28 preferably has at least one vacuum chamber 14, in particular a vacuum chamber 14 with the features described above and/or in particular in connection with a pump 17 and/or a gas reservoir 20. The system also optionally has a spectrometer, in particular a PL spectrometer 31, at least one microscope 27 and a computing unit 29. Optionally, the system 28 also contains a pressure sensor 23, which is designed to measure the internal pressure of the vacuum chamber 14 and optionally forward it to the computing unit 29. In one embodiment of the invention, the pressure sensor 23, the at least one microscope 27 and the spectrometer are connected to the computing unit 29, wherein the computing unit 29 is designed to measure the internal pressure of the vacuum chamber 14 determined by the pressure sensor 23 and/or at least during the step according to the invention ii) receiving and evaluating and displaying spectrometric measurement data obtained from the spectrometer and recordings of the perovskite precursor layer 11 or the forming perovskite layer 10 taken via the at least one microscope 27 . In particular, using the images of the at least one microscope 27 and/or the measurements taken using the spectrometer, it is provided to evaluate a density of crystallization nuclei and/or crystal growth in the perovskite precursor layer 11 or in the perovskite layer 10 during the method using a computer program.

7 1 shows a schematic of the method according to the invention compared to conventional vacuum drying, a printed perovskite precursor being processed into a perovskite layer 10. FIG. For this purpose, a perovskite precursor is first applied to a substrate 12, in particular printed, in order to produce a perovskite precursor layer 11 there. The application or printing can be done by a A large number of methods are used, such as inkjet printing, spin coating, slot die coating, blade coating, blade coating or spray coating. Inkjet printing in particular has proven to be advantageous for the method according to the invention. An ABX3 system is preferably used as the perovskite precursor, having, for example, methylammonium (MA), cesium (Cs) and/or formamidinium (FA) as component A, while component B is frequently given by lead (Pb). X is, for example, iodine (I), bromine (Br) and/or chlorine (Cl) or a mixture of these elements. The perovskite precursor also contains one or more solvents such as dimethylformamide, dimethyl sulfoxide and/or γ-butyrolactone as a solvent component. However, acetonitrile, 2-methoxyethanol, N-methyl-2-pyrrolidone can also be used as solvents for the perovskite precursor. For example, the inkjet printed perovskite precursor uses Cs0.05(FA0.83MA0.17)0.95Pb(10.83Br0.17)3 using a ternary solvent system consisting of dimethylformamide, dimethyl sulfoxide, and γ-butyrolactone to ensure ink functionality and printing requirements.

As in 7 indicated, the method according to the invention differs from conventional vacuum drying in that during the vacuum drying, ie during step ii) of the method according to the invention, a gas flow 13 flows over the perovskite precursor layer 11 or the forming perovskite layer 10, whereby the crystallization is accelerated and is improved in terms of the homogeneity of the forming perovskite layer 10. By controlling the gas flow 13, the so-called gas-assisted vacuum drying (GAVD), improved, optically dense and hole-free, ie laterally continuous, uninterrupted perovskite layers 10 can be achieved compared to conventional vacuum drying.

8th compares the results obtained with pure vacuum drying (ie without additional gas flow 13) with the method optimized according to the invention (ie with additional gas flow 13). In 8th therefore, the PL signal of the vacuum-dried perovskite precursor layer 11 or the forming perovskite layer 10 with the start of crystallization after about 200 s is shown at the top and the PL signal of the gas flow-assisted vacuum drying with the start of crystallization after about 35 s is shown at the bottom left. The internal pressure of the vacuum chamber 14 as a function of the process time is in 8th shown as a light line. Right below in 8th shows the development of the wavelength of the PL peak and the associated height of the PL peak. It becomes clear that with pure vacuum drying it takes more than 200 s until a PL signal is recorded due to the onset of crystallization of the perovskite precursor layer 11 . In contrast to this, accelerated crystallization of the wet perovskite precursor layer 11 is achieved within 35 s in the method optimized according to the invention. Here, the additional gas flow 13 causes an enormous change in the development of the start of crystallization, as the corresponding PL traces in the illustration at the bottom right prove. While the PL peak rises sharply in the case of the method according to the invention before flattening out, only a linear increase is observed for the vacuum-dried sample, indicating different crystallization dynamics for the two different processes (hollow symbols). This finding also applies to other gas flow rates. In addition, a strong red shift of the PL peak position from 690 to 740 nm indicates the crystal growth process from small seed crystals to larger perovskite intermediates in the case of the inventive method (solid symbols). In contrast, for the purely vacuum-dried samples, the PL signal only shifts from 730 to 740 nm. This narrow red-shift can be explained by the slower supersaturation, which does not allow for complete formation of cluster and coordination complexes, resulting in only partially crystallized material , as reported by Fateev et al. discussed [4]. The overall low PL peak of 740 nm at the end of the vacuum drying process can be attributed to the competing formation processes of bromide- and iodide-rich intermediate phases of the mixed halide MHP composition [5]. In both cases, a PL peak at 760 nm corresponding to the final perovskite layer 10 is measured after annealing.

9 shows images of the perovskite precursor layer 11 and the forming perovskite layer 10 during the in 8th measurements shown, with the corresponding points in time also in 8th are marked. The images were taken with a light microscope and show microscopic images of the drying behavior at different times of the conventional vacuum drying process (above) and the method optimized according to the invention (below).

With regard to the crystallization process, a darker, cloudy, optically denser layer is observed in the sample processed with the method according to the invention compared to light brown and cloudy layers of the vacuum-dried sample. The drying dynamics are also different: vacuum-dried samples dry from the outside to the middle of the layer due to the higher surface-to-volume ratio at the sample edges, where the saturation concentration is reached earlier. In contrast to the samples processed with the method according to the invention dry much faster and crystallize along the direction of the gas flow 13, which also indicates that the gas flow 13 as such and not only the increased pressure is of great importance. N ₂ was used as the process gas here, but any gas or any gas mixture can be used.

In order to get a clearer picture of the different formation kinetics, 10 X-ray diffraction (XRD) measurements on vacuum processed and annealed samples shown. On the left are the X-ray diffraction measurements of the samples, which are shown directly after the conventional vacuum drying method (first panel from the top) and after subsequent annealing (second panel from the top) of the perovskite layers 10 at 100°C. X-ray diffraction measurements of the samples are also shown, which were carried out using the method according to the invention (third panel from the top) and after subsequent annealing (fourth panel from the top) of the perovskite layers 10 at 100° C. Labeling is as follows: * marks the reflections of the tetragonal phases of the perovskite (100, 110, 111, 200), # marks the PbI2 reflection, § marks the MA2DMSO2Pb3l8 intermediate phase according to Cao et al. [6]. After vacuum drying, reflections from the MA2DMSO2Pb3l8 intermediate phase [6] and reflections from the perovskite phase are visible. In contrast, with the sample treated according to the method according to the invention, only a strong reflection at 6.7° 2Theta, as well as reflections at 13.7°, 19.9° and 26.7° can be observed, which indicate phase purity. In both cases we see a complete transformation to the tetragonal perovskite structure with main peaks at 14.2° and 28.4° after elevated temperature annealing. A non-negligible Pbl2 reflection at 12.7° is also visible for both samples, which stems from excess lead in the precursor solution and incomplete MHP conversion. Despite the different crystallization and growth conditions, the resulting perovskite structures appear to be similar. This is due to the strong influence of the later high-temperature annealing step on the final perovskite crystal transformation and the balance of structural changes. However, the morphological changes, in particular the homogeneity and the hole density of the resulting perovskite layer 10, are largely influenced by the crystallization and nucleation process during the drying step, as shown in the images on the right in FIG 10 shown. These images show scanning electron microscopic (English: scanning electron microscope, SEM) images of a merely vacuum dried (b) and then annealed (c) and according to the inventive method processed (d) and then subsequently annealed sample (e), wherein the annealing at a temperature of 100 °C was carried out. The presented results clearly show that the targeted and controlled gas flow is the crucial process step to induce favorable crystallization in a vacuum drying process.

Taking into account previous knowledge, this novel gas flow-assisted vacuum drying can be understood and explained as a multi-stage process. First, the gas flow 13 increases the evaporation rate of the solvent, resulting in faster supersaturation and more homogeneous nucleation, consistent with recent reports [7,8]. Second, the gas flow 13 accelerates the removal of solvent vapors near the nuclei, leading to a locally increased concentration at the interface. Consequently, crystallization begins at the solvent-air interface where the gas flow 13 first encounters the sample. Third, the gas flow 13 induces a higher nucleation rate, leading to the formation of a highly oriented metastable crystal phase distributed over the wet film surface [9], from where the crystallites grow homogeneously, which is reflected in the red-shift of the PL peak and the narrow half-width of the PL peak [5] (see e.g 8th bottom right). Interestingly, the addition of gas flow 13 leads to the formation of a highly oriented MA2DMS02Pb318 interphase, from which the dense perovskite layer 10 grows. The combination of vacuum drying to vent excess solvent and anchoring of the printed film and the additional gas flow 13 therefore enables controlled crystallization and nucleation to form homogeneous and hole-free perovskite layers 10.

11 shows a solar cell in pin architecture, having a perovskite layer 10 produced according to the method according to the invention printed. With this architecture and the method according to the invention, very well defined, hole-free perovskite layers 10 with large grains are achieved straight away without further optimization.

In 12 eventually becomes the in 11 solar cell shown, having a perovskite layer 10 produced according to the method according to the invention, compared with a solar cell having a perovskite layer 10 produced according to a conventional vacuum drying process (ie without additional gas flow 13). With pin architecture and the method of the invention is at a high Open circuit voltage of 1.11V and low hysteresis achieves a maximum photo conversion efficiency of 16.0%. In 11 1 shows a current density-voltage characteristic of an inkjet-printed perovskite solar cell or part of a solar module with a perovskite layer 10 produced on a SAM layer according to the invention in comparison to a corresponding solar cell or solar module produced by conventional vacuum drying. The efficiency determined by means of maximum power point (MPP) tracking, ie the photoconversion efficiency of the solar cell or solar module produced according to the invention is 16% on average over 300 s. In comparison, the purely vacuum-dried samples only have efficiencies, ie photoconversion efficiencies of up to 4.5% at lower current density and open circuit voltage as a result of the irregular morphology and an increased hole density of the resulting perovskite layers 10 .

FF (%) PCE (%) Erfindungsgemäßes Vakuumtrocknen Rückwärts 21,5 1,1 70,7 16,8 Vorwärts 21,4 1,11 65,5 15,6 Herkömmlicher Vakuumtrocknungsprozess Rückwärts 14,7 0,78 38,9 4,5 Vorwärts 14,5 0,75 35,3 3,8 Further fine-tuning of the process parameters according to the invention using optical in-situ monitoring, in particular by means of a spectrometer or a PL spectrometer 31 and further adjustment of the carrier extraction layers, makes the method according to the invention the basis for reliable and scalable methods for producing solution-based, homogeneous, hole-free, large-area solar cells with record performance. Table 1: Comparison of various measured parameters of perovskite-based solar cells produced using the method according to the invention and using a conventional vacuum drying process Manufacturing process of the solar cell Forward/reverse bias V _OC ( V ) $J_{SC}\left(\frac{mA}{c{m}^2}\right)$

FF (%) PCE (%) Vacuum drying according to the invention Backward 21.5 1.1 70.7 16.8 Forward 21:4 1:11 65.5 15.6 Traditional vacuum drying process Backward 14.7 0.78 38.9 4.5 Forward 14.5 0.75 35.3 3.8

Finally, Table 1 shows various parameters of solar cells, with the corresponding values being measured for perovskite-based solar cells produced using the method according to the invention on the one hand and using a conventional vacuum drying process on the other hand. The values are from the in 12 taken from the measurement curves shown. It can be clearly seen that the method according to the invention results in significantly increased values for the short-circuit current J _SC and the open-circuit voltage Voc compared to a conventional vacuum drying process (ie without a gas flow 13 directed over the perovskite precursor layer 11 or the forming perovskite layer 10). corresponding solar cell result. Likewise, the fill factor (FF) and the efficiency or the PCE of a solar cell produced using the method according to the invention are superior to a perovskite-based solar cell produced using a conventional vacuum drying process.

Bibliography:

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Claims (15)

A method for producing a crystallized perovskite layer (10), comprising at least the steps: i) applying a perovskite precursor to a substrate (12), so that a perovskite precursor layer (11) is produced on the substrate (12) and ii) generating a negative pressure over the perovskite precursor layer (11), a process gas being flowed over the perovskite precursor layer (11) at the same time as the negative pressure, so that a crystallized perovskite layer (10) is formed. The procedure after claim 1 , characterized in that the perovskite layer (10) is annealed after step ii) or at the same time as step ii). The method according to one of the preceding claims, characterized in that the process gas flows in a gas flow (13), in particular parallel or at an in particular right angle, over the perovskite precursor layer (11). The method according to any one of the preceding claims, characterized in that the negative pressure p, in bar, and the gas flow (13) F, in l/s, are in a ratio x = p/F to one another, with x in the range of 1 mbar *s/l to 230 mbar*s/l. The method according to any one of the preceding claims, characterized in that the negative pressure is generated in a vacuum chamber (14) in which the substrate (12) with the perovskite precursor layer (11) is arranged, the vacuum chamber (14) being surrounded by at least one Withdrawal opening (15) is connected via a pump line (16) to a pump (17) which is designed to generate a negative pressure in the vacuum chamber (14), the vacuum chamber (14) being fed through at least one inlet opening (18) via a Gas line (19) is connected to a gas reservoir (20) of the process gas, the pump line (16) and the gas line (19) each having a valve (21, 22) which is designed to be opened to control the gas flow (13). or to be closed, and wherein a pressure sensor (23) is arranged between the two valves (21, 22), wherein the pressure sensor (23) is set up to detect a gas pressure in the vacuum chamber (14). The procedure after claim 5 , characterized in that the vacuum chamber (14) has a receptacle (24) designed to receive the substrate (12) with the perovskite precursor layer (11) or the perovskite layer (10) to be formed, with an upper side of the vacuum chamber having a transparent window ( 25) so that the substrate (12) arranged as intended on the receptacle (24) of the vacuum chamber (14) with the perovskite precursor layer (11) or with the perovskite layer (10) to be formed can be observed through the window (25). , and wherein the at least one inlet opening (18) and the at least one outlet opening (15) are arranged at the level of the receptacle (24), so that the gas flow (13) between the at least one outlet opening (15) and the at least one inlet opening (18) flows over the substrate (12) with the perovskite precursor layer (11) or the perovskite layer (10) to be formed, which is arranged as intended on the receptacle (24) of the vacuum chamber (14). The procedure after claim 6 , The receptacle (24) being thermally connected to a heating element (26) which is designed to heat the substrate (12) with the perovskite precursor layer (11) or the forming perovskite layer (10). The method according to any one of the preceding claims, characterized in that the perovskite precursor layer (11) or the forming perovskite layer (10) at least during step ii) and / or during the tempering by a measuring device for measuring a homogeneity of the perovskite precursor layer (11) or the perovskite layer (10) and/or for detecting defects within the perovskite precursor layer (11) or the perovskite layer (10). The procedure after claim 8 , characterized in that the measuring device comprises a spectrometer, in particular an optical spectrometer, the measuring device being arranged in such a way that a measurement is carried out via the window (25) of the vacuum chamber (14). The method according to one of the preceding claims, characterized in that at least during step ii) and/or during the tempering, photographs of the perovskite precursor layer (11) or of the forming perovskite layer (10) and in particular the recordings are evaluated with a computer program with regard to a density of crystallization nuclei and/or crystal growth in the perovskite precursor layer (11) or in the perovskite layer (10) during the method and in particular be issued to a user. The procedure according to one of the Claims 5 until 10 , the method being carried out with a system (28), the system (28) having the following components: - a vacuum chamber (14), which has a chamber for receiving a substrate (12) with a perovskite precursor layer (11) or a perovskite layer (10) to be formed, wherein an upper side of the vacuum chamber (14) has a transparent window (25), so that the substrate (12) arranged as intended on the receptacle (24) of the vacuum chamber (14) with the Perovskite precursor layer (11) or the perovskite layer (10) to be formed can be observed through the window (25), with at least one inlet opening (18) connected to a gas reservoir (20) and at least one inlet opening (18) connected to a gas reservoir (20) for pumping out the vacuum chamber ( 14) trained pump (17) connected exhaust opening (15) of the vacuum chamber (14) are arranged at the level of the receptacle (24), so that the gas flow (13) between the at least one exhaust opening (15) and the at least ei an inlet opening (18) over the substrate (12) arranged as intended on the receptacle of the vacuum chamber (14) with the perovskite precursor layer (11) or with the perovskite layer (10) to be formed, with between the at least one inlet opening (18) and the gas reservoir (20) and the at least one extraction opening (15) and the pump (17) each have a valve (21, 22) which can be opened or closed at least partially in order to shut off the gas flow (13). control, and wherein a pressure sensor (23) for displaying and/or forwarding an internal pressure of the vacuum chamber (14) is arranged between the two valves (21, 22), - a spectrometer which is designed for this, at least during step ii) and/ or carry out spectroscopic measurements of the perovskite precursor layer (11) or the forming perovskite layer (10) during the tempering, - at least one microscope (27) which is designed for this purpose, at least during step ii) and/or to take pictures of the perovskite precursor layer (11) or the forming perovskite layer (10) during the tempering and - a computing unit (29), having a processor, which is used to exchange commands and data with the pressure sensor (23), the spectrometer and the at least one microscope (27). The procedure after claim 11 , wherein the system (28) further comprises a heating element (26) which is designed to heat the substrate (12) with the perovskite precursor layer (11) or the forming perovskite layer (10). Use of the method according to any one of Claims 1 until 12 for the production of a solar cell, an LED, a photodetector, a thin-film transistor, a memristor, and/or an optically pumpable laser. A system (28) for producing a perovskite layer (10), having at least the following components: - a vacuum chamber (14), which is used to hold a substrate (12) with a perovskite precursor layer (11) or a perovskite layer (10 ) formed receptacle (24) and wherein an upper side of the vacuum chamber (14) has a transparent window (25), so that the substrate (12) with the perovskite precursor layer (11 ) or the perovskite layer (10) to be formed can be observed through the window (25), and wherein in each case at least one inlet opening (18) connected to a gas reservoir (20) and in each case at least one with a pump designed to pump out the vacuum chamber (14). (17) connected exhaust opening (15) of the vacuum chamber (14) are arranged at the level of the receptacle (24), so that the gas flow (13) between the at least one exhaust opening (15) and the at least one inlet opening ung (18) flows over the substrate (12) arranged as intended on the receptacle (24) of the vacuum chamber (14) with the perovskite precursor layer (11) or with the perovskite layer (10) to be formed, with between the at least one inlet opening ( 18) and the gas reservoir (20) or the at least one extraction opening (15) and the pump (17), a valve (21, 22) is arranged in each case, which can be opened or closed at least partially in order to control the gas flow (13 ) to control, and between the two valves (21,22) a pressure sensor (23) for displaying and / or forwarding an internal pressure of the vacuum chamber (14), - a spectrometer which is designed to carry out spectroscopic measurements of the perovskite precursor layer (11) or the forming perovskite layer (10) at least during step ii) and/or during the tempering, - at least a microscope (27) which is designed to take optical pictures of the perovskite precursor layer (11) or the forming perovskite layer (10) at least during step ii) and/or during the tempering and - a computing unit (29), having a processor which is connected to the pressure sensor (23), the spectrometer and the microscope (27) in order to exchange commands or data. The system after Claim 14 , Additionally having a heating element (26) which is designed to heat the substrate (12) with the perovskite precursor layer (11) or the forming perovskite layer (10).

Images