Embodiments relate to a method of manufacturing a layer including perovskitic material, to a method of producing an electrooptical and/or optoelectronic device.
For some years, perovskitic materials, for example CH3NH3PbI3, have been gaining increasing significance owing to their optoelectronic properties. Perovskitic materials have gained attention as high-efficiency, electrooptical or optoelectronic semiconductor materials since perovskites permit efficient conversion of electrical energy to electromagnetic radiation energy and of electromagnetic radiation energy to electrical energy. Use of perovskitic material in solar cells leads to an increase in efficiency to more than twice the previous standard.
In high-efficiency semiconductor components, layers of electrooptical semiconductor material are regularly required. Numerous methods are known for layer production of perovskitic material.
The methods include, for example, the OSPD (“one-step precursor deposition”) method, two-source coevaporation, the SDM (“sequential deposition method”), the VASP (“vapor-assisted solution process”) method, the interdiffusion method and the method of spray coating from solution.
In spite of the promising properties of perovskitic material mentioned, there has to date been no large-scale use in optoelectronic components. For example, manufacture high-efficiency components including perovskitic material have been possible only under laboratory conditions and under suitable ambient atmospheres. Perovskitic material does not have sufficient long-term stability at present under the influence of ambient air: for example, water molecules destroy the crystal lattice structure of the perovskitic material.
Moreover, the production of relatively large areas or the production of layers of relatively large thickness remains complex and costly.
The scope of the present invention is defined solely by the appended claims and is not affected to any degree by the statements within this summary. The present embodiments may obviate one or more of the drawbacks or limitations in the related art.
Embodiments provide a method of manufacturing a layer including perovskitic material that is simple and inexpensive and provides a material having improved long-term stability. Embodiments provide a method of producing an electrooptical and/or optoelectronic device and a device, for example, an electrooptical or optoelectronic device, including a layer including perovskitic material that may be implemented inexpensively and provide long-term stability.
In an embodiment of a method for manufacturing an electrooptical and/or optoelectronic layer, the layer including perovskitic material of the composition ABX3 is formed by cold gas spraying of at least one starting material including the perovskitic material. X is formed by at least one halogen or a mixture of two or more halogens. The term “perovskitic material” in the context of this application is understood to refer to a material including a perovskitic crystal structure of the ABX3 form. The A position is occupied by a cation or a mixture of different cations, the B position by a metallic or semi-metallic cation or a mixture of different cations, and the X position, as already described above, by a halogen or a mixture of different halogens. The composition also includes materials includes a stoichiometry that differs slightly from A:B:X=1:1:3, i.e. by at most 0.05 from the proportion specified in each case.
In an embodiment of a method, the starting material including the perovskitic material is in powder form that is converted to a layer, appropriately at room temperature. The perovskitic material forms an aerosol with a stream of cold gas. The gas temperature may be at most 200 degrees Celsius, at most 70 degrees Celsius, or at most 40 degrees Celsius. The aerosol forms a stream of the starting material including the perovskitic material onto a substrate, with aggregation of the material to form a continuous layer.
The aerosol is driven through a nozzle owing to a pressure differential and accelerated in the process.
The aerosol may be accelerated against a low pressure of at most one hundred, for example, of at most ten, mbar that may be referred to as aerosol deposition method (ADM) or—synonymously—as aerosol-based cold deposition.
The powder during the coating undergoes barely any change in its chemical composition, if any. By contrast, for methods known to date that the perovskitic material undergoes chemical change during the coating or is only formed in the coating operation. According to embodiments, the perovskitic material may therefore advantageously first be synthesized and subsequently converted to a layer virtually without any change in the chemical structure.
Embodiments provide for manufacture of a compact, e.g. a dense and nonporous, layer including perovskitic material. The contact area between perovskitic material and ambient atmosphere is kept extremely small. Only a relatively small proportion of the perovskitic material is exposed to water molecules from the ambient atmosphere, and so the perovskitic lattice structure is substantially conserved. Any significant deterioration in relevant material properties for use as active semiconductor material is consequently effectively prevented. For a layer including perovskitic material that is manufactured in accordance with an embodiment, any deterioration in charge carrier mobility, that otherwise is taken into account, and accordingly any decrease in the diffusion lengths, resulting in a blue shift of the absorption edge, known as the so-called “yellow changeover”, occur in a greatly retarded manner, if at all.
High-efficiency devices including perovskitic material that are suitable for practical use may be manufactured. The long-term stability of layers including perovskitic material thus reaches marketable values. Consequently, even in the case of devices including layers including perovskitic material, the lifetime of the devices is not necessarily limited by that of the perovskitic material, e.g. the long-term stability of the layers and devices is distinctly improved.
Moreover, the crystal lattice structure of the perovskitic material is conserved. Specifically, in the case of films, in the conventional production of layers including perovskitic material, residues of the starting material that remain are found to be disadvantageous. Residues of lead iodide have a distinct effect on the long-term stability of layers including perovskitic material. For example, in the case of the conventional OSPD method, such residues are a problem. Embodiments provide that any such unwanted effect on the manufactured layer is already ruled out owing. No other changes in the crystal lattice structure of the perovskitic material occur either.
In addition, the method may be conducted easily and inexpensively. The implementation of high layer thicknesses of at least one micrometer or more is readily achievable by the method.
Further advantageously, very small layer thicknesses of less than one micrometer and less than 300 nanometers are also easily possible through appropriate choice of the method parameters.
Layer thicknesses in the sub-micrometer range down to the high micrometer range are achievable and layers thus manufactured are suitable for a wide variety of different applications. Manufacturing two-dimensional areas of layers including perovskitic material of any extent is also possible.
Cold gas spraying is affected by aerosol-based cold deposition. Embodiments may be conducted at a temperature of at most 200 degrees Celsius, at most 70 degrees Celsius, or at most 40 degrees Celsius.
The retention of the perovskite lattice structure of the perovskitic material is assured in a simple manner since the comparatively low breakdown temperature is not attained in this way.
Consequently, the method opens up inexpensive manufacture also of thick and/or large-area layers by comparison with known methods.
Since, by comparison with conventional methods, for example as specified above, the material synthesis (for example from solution) does not coincide directly with the layer formation, and the two steps may instead be conducted separately from one another, the method provides a higher degree of process control and optimization of material and layer formation. Moreover, a high deposition rate enables coating of large areas within a short time and thus in an economically viable manner.
For the aerosol-based cold deposition, a plant as described in U.S. Pat. No. 7,553,376 B2 may be used. The disclosure content of the published specification cited is explicitly incorporated by reference in so far as it relates to the plant or the execution of the method.
In an embodiment, the cold gas spraying is conducted in an operating atmosphere including at most 30 percent relative humidity, at most 20 percent relative humidity, or at most 10 percent relative humidity. In the method, the cold gas spraying is conducted in an operating atmosphere (also referred to as chamber pressure in the literature) with a pressure of at most 100 bar or at most 10 mbar.
The generation of extraneous phases that may act as degradation seeds is avoided during the method. The retention of the perovskite lattice structure of the starting material present in the starting material that is envisaged is readily possible. Any chemical change in the perovskitic material is effectively avoided.
In an embodiment, the cold gas spraying is conducted in inert atmosphere.
The generation of extraneous phases that may act as degradation seeds is effectively avoided.
In an embodiment, the layer is formed with a layer thickness, at least in regions, of at least one, e.g. at least three, and appropriately at least ten micrometers. The layer is formed with a layer thickness, at least in regions, of at least 30, e.g. at least 100, micrometers.
In an embodiment, the layer is formed with a layer thickness, at least in regions, of at most 1 μm, at most 500 nm or at most 200 nm.
The layers of perovskitic material reach such thicknesses as required in optoelectronic components such as energy transducers and radiation detectors, for example, x-ray detectors.
In an embodiment, the layer is formed with a mixture including the perovskitic material and at least one further material that is especially non-perovskitic and may form islands in the perovskitic material.
In an embodiment, the layer is formed as at least one sublayer in a succession of this at least one sublayer and at least one further sublayer. The at least one further sublayer is formed with at least one further, especially non-perovskitic, material.
The at least one further material may be an electron-conducting and/or electron-collecting material, e.g. TiO2, and/or a hole-conducting and/or hole-collecting material, e.g. spiro-MeOTAD, and/or an electrically insulating material and/or an injection material, e.g. PEDOT:PSS or F8, and/or an inert material and/or an optically transparent material, especially glass and/or quartz and/or FTO (“fluorine-doped tin oxide”) glass.
The contact zone between the individual functional materials or functional layers is optimized, that according to the further material, provides better charge carrier extraction in collection layers and/or optimizes the light-emitting properties of the layer and/or prevents possible ion exchange in the case of processing of different variants of perovskitic material.
The gas component utilized in the aerosol-based cold deposition may be oxygen and/or nitrogen and/or an inert gas, e.g. argon and/or helium, and/or hydrogen and/or mixtures with hydrogen.
In production of an electrooptical and/or optoelectronic device having at least one electrooptical and/or optoelectronic layer, the at least one electrooptical and/or optoelectronic layer including a perovskitic material is formed by a method for manufacture of a layer including perovskitic material as described above.
In electrooptical and/or optoelectronic devices, the manufacture of an electrooptical and/or optoelectronic perovskitic layer of maximum density is crucial. By the method, as described above, the electrooptical and/or optoelectronic layer may be manufactured in dense form and with high layer thickness. The device including such a layer consequently includes high electrooptical and/or optoelectronic efficiency and at the same time a long lifetime.
The device may be an energy transducer or a radiation detector, e.g. an x-ray detector, and/or the electrooptical and/or optoelectronic layer is a sensor layer.
For devices in the form of energy transducers and radiation detectors, the manufacture of the electrooptical and/or optoelectronic perovskitic layer with a high layer thickness and low porosity is crucial for its efficiency and lifetime. The prerequisites that are essential for the practical utility of the device may readily be achieved.
In an embodiment, at least one further sensor layer is manufactured in a direction oblique, e.g. at right angles, to a direction of growth of the at least one sensor layer.
“Direction of growth” refers to the direction in which the layer adds on, e.g. appropriately the normal to a surface of the substrate on which the layer adds on and/or the normal to the two-dimensional extents of the layer.
In the case of radiation detectors, multiple sensor layers may be implemented in the manner of detector pixels, such that spatially resolved detection of electromagnetic radiation is possible if appropriate.
In an embodiment, a device including at least one layer including perovskitic material is formed.
The device may be an energy transducer configured for conversion of electromagnetic energy to electrical energy or of electrical energy to electromagnetic energy.
The device may be a solar cell or a light-emitting diode.
The device may be an x-ray detector.
The plant 10 depicted in
A method of an embodiment is conducted by the plant 10 as follows: the vacuum pump 30 pumps the vacuum chamber 20 to a vacuum, for example, to a reduced pressure of a few millibars, e.g. five millibars. The aerosol source 40 is outside the vacuum chamber 20 and mixes a gas, for example oxygen and/or nitrogen, with particles 60 of perovskitic material and provides an aerosol 70. The perovskitic material is provided beforehand by known chemical methods.
The aerosol source 40 is operated, for example, at standard pressure, e.g. atmospheric pressure. As a consequence of the pressure difference between aerosol source 40 and vacuum chamber 20, the particles 60 are transported from the aerosol source 40 into the vacuum chamber 20 via a connecting conduit 80 that connects the aerosol source 40 and the vacuum chamber 20. The connecting conduit 80 extends into the vacuum chamber 20 and, at an end within the vacuum chamber 20, opens into a nozzle 50 that further accelerates the aerosol stream and consequently the particles 60. In the vacuum chamber 20, the particles 60 meet a substrate 90 moving in x direction, where the particles 60 form a dense film 100.
The particles 60 in the aerosol source 40 are in the form of pulverulent perovskitic material prior to mixing with the gas component of the aerosol 40. The particles 60 form a likewise perovskitic film 100 on the substrate 90, with the perovskitic material remaining unchanged in its chemical structure throughout the method.
In an embodiment a structure control unit is provided, that monitors the crystal lattice structure of the film 100 by x-ray diffractometry. Measurements show that the perovskitic crystal lattice structure of the pulverulent starting material on application to the substrate 90 is regularly fully conserved. Secondary phases do not occur in the film 100.
In an embodiment, the perovskitic material is an organometallic halogen, CH3NH3PbI3, the substrate 90 in the present case, a glass substrate. The perovskitic material may, in further working examples that are not presented separately, be a different perovskitic material including optoelectronic properties. Moreover, in further working examples that are not presented separately, other substrates may be used, for example glasses or substrates that have already been provided with other layers.
The perovskitic material CH3NH3PbI3 used in the working example presented includes optoelectronic properties that identify the material as suitable as an energy transducer for conversion of electrical energy to electromagnetic radiation energy and vice versa. For example, the absorption spectrum of this perovskitic material includes an absorption edge in the wavelength range between 750 nanometers and 800 nanometers and an absorption across the entire visible wavelength range (350 nanometers to 800 nanometers). At an excitation wavelength of 405 nanometers for this perovskitic material, the emission spectrum may show a main maximum at 780 nanometers in the immediate proximity of the absorption edge. The absorption and emission characteristics mentioned are typical of other perovskitic materials too.
An embodiment of the aerosol-based cold deposition results in a crystalline structure including low porosity, e.g. including high density that corresponds to the theoretical density.
In an embodiment, extended layers and layers of virtually any thickness may be produced. For example, the layer 100 is manufactured in several hundreds of micrometers. The layer may, in further working examples that are not presented separately, be thinner by a factor of 10, for example. In addition, the method as presented hereinafter offers the possibility of combining multiple materials.
For example, in further working examples different pulverulent starting materials may be mixed before or during the process of aerosol-based cold deposition. For example, in a working example, different variants of perovskitic materials (e.g. CH3NH3PbI3 and CH3NH3PbBr3) are used.
In an embodiment, as depicted in
Using different starting materials, for example, the contact zone between the respective functional materials or functional layers is optimized, for example in order to provide better charge carrier extraction in collecting layers, in order to optimize the light-emitting properties of the functional material, or in order to prevent possible ion exchange in the processing of different variants of perovskitic materials.
In an embodiment, an LED includes a layer manufactured for conversion of electrical energy to optical energy. TiO2 is the further material 130 in the manner of a “mesoporous perovskite solar cell”.
In further embodiments, such a mixture of layers is implemented by a sequence of layers of different materials.
For example, different materials may be deposited in succession: for example, perovskitic materials of different compositions are deposited and/or perovskitic materials are deposited successively with a different material, for example hole conductor, electron conductor, injection layers, inert material, optically transparent material, structure material etc., or mixtures of starting materials as described above.
The solar cell 135 forms a device with a layer including perovskitic material in the manner of an energy transducer and includes a carrier substrate 140 (glass in the present case, for example), and each of the following deposited successively layer by layer: a transparent electrode 150 formed with FTO (“fluorine-doped tin oxide”) glass in the example shown, an electron collecting layer 160 (TiO2 in the present case, for example), an electrooptical and optoelectronic, perovskitic layer 170 (for example CH3NH3PbI3), a hole collecting layer 180 (for example spiro-MeOTAD), and an electrode 190 (for example gold. At least the electrooptical and optoelectronic layer formed with perovskitic material and, in other embodiments, one or more of the other layers have been produced by aerosol-based cold deposition. The electrooptical and optoelectronic perovskitic layer 170 may additionally, in an embodiment not presented separately, as well as perovskitic material, also additionally include other materials as elucidated above with reference to
The mode of function of the solar cell 135 with the sequence of layers shown in
The mode of function of the light-emitting diode 200 is as follows: the application of an external voltage to the electrodes 150 and 240 causes injection of holes and electrons from the respective injection layers 210 and 230 into the electrooptical and optoelectronic layer 220 formed with perovskitic material, where light formed as a result of the recombination thereof can leave the light-emitting diode 200 through the transparent layers of carrier substrate 140, electrode 150, and injection layer 210. By production of layers from mixtures of one or more perovskitic materials and one or more suitable other materials by aerosol-based cold deposition, the properties of the electrooptical and optoelectronic layer 220 formed with perovskitic material are influenced such that, for example, an increase in the charge carrier recombination rate and hence modification/optimization of the luminous efficiency of the light-emitting diode 200 are achieved.
Further embodiments of a device including a layer including perovskitic material are depicted in
For this purpose, the x-ray detector 260 also includes a sequence of layers:
Similarly to the preceding embodiments, a first electrode 270 and a second electrode 280 surround an electrooptical and optoelectronic layer 290 formed with perovskitic material. The arrangement is manufactured by depositing the electrooptical and optoelectronic layer 290 formed with perovskitic material onto the first electrode 270 by aerosol-based cold deposition of perovskitic material. Subsequently, the further electrode 280 is applied to the layer 290.
The function of the x-ray detector is as follows: electromagnetic radiation in the x-ray to UV range, in the representation according to
Alternatively, the electrodes 270, 280 may be applied laterally to a substrate material and, in a subsequent step, covered with the electrooptical and optoelectronic layer of perovskitic material. Such a possible embodiment of an x-ray detector 300 is depicted in
With the aid of the aerosol-based cold deposition, large-area coatings provide production of arrangements that provide spatially resolved detection of radiation. For such a detection of the photocurrent, in the working example according to
It is to be understood that the elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent, and that such new combinations are to be understood as forming a part of the present specification.
While the present invention has been described above by reference to various embodiments, it may be understood that many changes and modifications may be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.
Number | Date | Country | Kind |
---|---|---|---|
102016202607.0 | Feb 2016 | DE | national |
The present patent document is a continuation of PCT Application Serial Number PCT/EP2017/053636, filed Feb. 17, 2017 designating the U.S., which is hereby incorporated by reference in its entirety. This patent document also claims the benefit of DE 102016202607.0, filed on Feb. 19, 2016, which is also hereby incorporated by reference in its entirety.
Number | Date | Country | |
---|---|---|---|
Parent | PCT/EP2017/053636 | Feb 2017 | US |
Child | 16104732 | US |