Method for producing multi-component perovskites

Abstract

This invention provides a method for forming a perovskite material from multiple evaporation sources. [Solution] In the present invention, (i) a first evaporation source comprising a mixture of co-sublimable organic halides, and (ii) a second evaporation source comprising one or more metal halides having the following formula (I), wherein B(X y X' 1-y )2(i) a method is provided which comprises the steps of co-sublimating a second evaporation source, where B is a divalent metal cation, X and X' are different halides, 0 ≤ y < 1, and (iii) one or more different organic halides from one or more other evaporation sources, and / or (iv) one or more inorganic halides from one or more other evaporation sources, wherein the perovskite material comprises three or more different cations in addition to the B cation.

Description

[Technical Field]

[0001] The present invention relates to a co-sublimation deposition process for producing a multi-component perovskite thin film, wherein the multi-component perovskite thin film has at least three or four cations at position A, one or two cations at position B, and one, two or more halide components, and the process requires fewer evaporation sources than the number of components. The present invention also includes the use of a large monovalent cationic additive, which can be co-sublimated with another organic monovalent cation to improve the crystallinity and thermal stability of the final perovskite material. [Background technology]

[0002] Solar energy conversion is one of the most promising technologies for providing renewable energy.

[0003] One class of photovoltaic materials that has attracted considerable attention in recent years is organic-inorganic halide perovskites. These materials have a perovskite crystal structure represented by the general formula ABX3. These materials exhibit a favorable band gap, high absorption coefficient, and long diffusion length, and such compounds have been found to be ideal as absorbers in photovoltaic devices.

[0004] Typical techniques for synthesizing perovskite thin films can range from wet solution processes such as spin coating, inkjet, and blade coating, to dry processes such as deposition methods including thermal deposition, chemical vapor deposition (CVD), and aerosol-assisted CVD. Dry processes like deposition are ideal solvent-free techniques, minimizing damage to pre-existing device layers and allowing for better control of film thickness and uniformity. When producing complex multi-component perovskite compositions, wet processes are often used because dry processes tend to become more complex as additional components are introduced into the perovskite structure. In particular, controlling perovskites containing several different components (e.g., four or more components) can be challenging in co-evaporative vacuum deposition techniques. Such multi-component perovskites require many evaporation sources, each with its own monitored settings, and the need to carefully control the various deposition rates of each corresponding precursor, making the overall process complex and expensive, especially if one or more precursors sublimate from the same source.

[0005] An attempt to overcome such implementation complexities is reported in Kam et al., “Efficient Mixed Cation Mixed Halide Perovskite Solar Cells by All-Vacuum Sequential Deposition Using Metal Oxide Electron Transport Layers,” Solar RRL, Vol. 3, 7, 2019. This paper investigates the preparation of mixed perovskites using a vapor phase process, involving a first step of a single quartz microbalance (QCM), where lead halides are deposited first, followed by organic iodides, instead of co-volatilizing multiple source materials. First, PbI2 and PbBr2 salts are mixed in an optimal ratio, co-evaporated by heating current, and then deposited on a substrate. Next, methylammonium iodide (MAI) and formamidinium iodide (FAI) are mixed in an optimal ratio and co-sublimate due to their similar sublimation temperatures, enabling a similar deposition rate to the corresponding mixed lead halide film. Although multi-component perovskites are synthesized, introducing extra steps, unlike single simultaneous deposition, significantly accelerates processing time and fails to address the problem of implementing a simplified "all-in-one" simultaneous evaporation process that helps maintain the uniformity of the final perovskite material.

[0006] Furthermore, Ball et al.'s "Low Bandgap FA for Photovoltaic Power" 1-x Cs x Sn 1-y Pb y In "Dual-source co-evaporation of I3 perovskites," ACS Energy Lett. 2019, 4, 11, 2748-2756, 2019, multi-component perovskites, i.e., FA, are discussed. 1-x Cs x Sn 1-y Pb yA dual-source co-evaporation method for manufacturing I3 is provided. In a single crucible source, a mixture of metal iodides of Cs, Pb, and Sn cations is prepared, melted under an inert atmosphere, and then naturally cooled to room temperature. Also, SnF2 is added to this mixture to control crystallization and inhibit the formation of impurity phases in the final film. Separately, FAI is provided by a second source. Next, the two source materials are co-evaporated to produce a crystalline low-bandgap perovskite thin film. The number of evaporation sources is minimized to two, and a five-component perovskite can be produced. However, this type of perovskite generally has low stability because the Sn component is particularly prone to oxidation. SnF2 is a well-known passivating agent that provides excess Sn 2+ ions and compensates for the oxidized Sn 4+ . However, this material does not necessarily improve the thermal stability, which is an important issue for most complex perovskites. Therefore, there is still a need to optimize the process to obtain stable perovskites.

[0007] Previous studies on the vacuum deposition of wide-bandgap trivalent cation perovskites by four-source co-sublimation were conducted by Gil-Escrig et al. (Vacuum-deposited trivalent cation mixed halide perovskite solar cells, Advanced Energy Materials, Vol. 8, Issue 14, 2018). In particular, the Cs 0.5 FA 0.4 MA 0.1 Pb(I 0.83 Br 0.17 )3 perovskite film can be prepared from PbI2, CsBr, FAI, and MAI. CsBr has been shown to serve as a source for both Cs + and Br - . However, to increase the bandgap (Eg>1.7 eV), a significant amount of Br -The incorporation of cesium is necessary, resulting in a similarly high cesium concentration, which leads to irregular morphology and degrades the properties of the resulting device. Therefore, careful consideration is required when selecting the precursor of the mixed halide compound. Consequently, it is preferable to mix two different metal halides in a single source to better control the stoichiometry. For this reason, further research similar to that of Gil-Escrig et al. was conducted by Munoz et al. ("Room Temperature Vacuum Deposition of CsPbI2Br Perovskite Films from Multiple Sources and Mixed Halide Precursors," Chem. Mater., 32, 8641, 2020). Here, CsI was used as the cesium source, while the precursors PbI2 and PbBr2 were pre-mixed instead. In this process, a uniform CsPbI2Br perovskite film was obtained, but its thermal stability was found to be significantly insufficient. Therefore, even when using a co-evaporation process of mixed halides, it is difficult to control all parameters of the perovskite film. To overcome a lack of stability, additional features, such as additive engineering, are often required.

[0008] Otalora et al., “Hybrid Perovskite Films Deposited by Thermal Evaporation from a Single Source,” J Mater Sci:Mater Electron, 2021, provides a method for depositing MAPbI3 films by thermal evaporation from a single source. However, this method only supports the deposition of extremely simple perovskite films and uses only one type of A, B, and X ions. Furthermore, it is necessary to study highly specific pressure, temperature, and solvents to obtain desirable morphology and electrical properties, similar to those obtained in the case of co-evaporation from two sources.

[0009] Addition engineering to improve the stability properties of perovskites has been a well-established technique. Recent interest has been directed towards the addition engineering of large cations, such as the partial substitution of A cation sites with guanidinium (GA) ions. For example, in Jodlowski et al.'s "Large Guanidinium Cations Mixed with Methylammonium in Lead Iodide Perovskite for 19% Efficiency Solar Cells," Nature Energy, 2, 927-9279, 2017, a perovskite with improved thermal and environmental stability is obtained by inserting GA into a portion of the A unit of the MAPbI3 structure during a spin-coating process, due to the availability of H bonds with a preferred orientation within the inorganic backbone. Building on this, Zhang et al.'s "Guanidinium-Induced Phase-Separated Perovskite Layer for Efficient and Extremely Stable Solar Cells," J.Mater.Chem.A, 2019, 7, 9486-9496, describes a composite quadruple-cation perovskite, Cs 0.05 (Fa 0.83 (MA 1-x GA x ) 0.17 ) 0.95 Pb(I 0.83 Br 0.17 )3 is spin-coated, which has shown improved stability properties. By adjusting the GA content, 3D CsFAMA 1-x GA x This induced hexagonal δ-FAPbI3 phase separation. GA-based perovskites have been reported to possess minimal hysteresis and excellent photoelectronic properties.

[0010] Similarly, Yerramilli et al. ("Introduction of Phenylethylammonium Iodide to Inverted Triple Cation Perovskite Solar Cells for VOC and Stability," Organic Electronics, 93, 2021) have shown that introducing phenylethylammonium (PEA) into FAMACs-based perovskite compositions improves film morphology and results in a uniform film with extremely few pinholes. A one-step solution-based method is used to synthesize the perovskite film. [Overview of the project] [Problems that the invention aims to solve]

[0011] Addition engineering is a beneficial technique for solution-treated perovskites, but this type of structural effect is often not reproducible by sublimation techniques. For example, in La-Placa et al.'s "Vacuum-Deposited 2D / 3D Perovskite Heterojunctions," ACS Energy Lett. 2019, 4, 12, 2893-2901, the fabrication of perovskites by dual-source vacuum deposition is demonstrated, using addition engineering of large cations with phenethylammonium. This method involves co-sublimation deposition of phenethylammonium lead iodide (PEAI) and PbI2, forming a 2D layer on either side of the 3D MAPbI3 layer of PEA2PbI4. As a result, the 2D iodide (PEA2PbI4) formed a layer on either side of the 3D MAPbI3 film. However, the unfavorable orientation of the 2D perovskite relative to MAPI hinders charge extraction, and evidence of surface passivation tends to be lacking compared to the corresponding solution-treated method. [Means for solving the problem]

[0012] In a first aspect of the present invention, the method described in claim 1 is provided.

[0013] Increasing the number of components (particularly the number of A cations and / or X halides) in ABX3 (B=Pb, Sn) perovskite formation offers advantages in terms of material / device properties and environmental stability. However, vacuum co-evaporation requires a corresponding increase in the number of evaporation sources, which increases the complexity of the film deposition process.

[0014] The present invention provides the synthesis of high-performance multi-component perovskites via an efficient co-evaporation process that requires fewer source materials than the present components, thereby facilitating partial substitution of the A-site with large cationic additives to enhance thermal stability. Accordingly, the described process and its corresponding perovskites are suitable for use in semiconductor devices, including photovoltaic devices, single-junction solar cells, or multi-junction solar cells, including perovskite-silicon tandem cells, all-perovskite tandem solar cells, perovskite-perovskite-silicon cells, perovskite-CdTe tandem cells, perovskite-CuZnSnSSe tandem cells, perovskite-CuZnSnS tandem cells, and perovskite-CIGS tandem cells.

[0015] The literature provides solutions for thermal instability in solvent-treated perovskites. However, in many cases, these solutions do not produce the same effect on perovskites prepared by sublimation (see, for example, the effect of adding large cations to the surface of solution-treated perovskites to form quasi-2D perovskites, which is not obtained when prepared by sublimation. ACS Energy Lett. 2019, 4, 12, 2893-2901).

[0016] The method of the present invention provides a clear solution to conventionally experienced problems and offers the ability to impart improved thermal stability through addition engineering while maintaining a crystalline single-phase perovskite structure, through an efficient and easily manageable simultaneous operation vacuum deposition process.

[0017] The present invention will be described in more detail below, with reference to the attached drawings, as an example. [Brief explanation of the drawing]

[0018] [Figure 1] This figure shows elemental and stoichiometric analyses of the mixed lead halide Pb(I1-xBrx)3 material after moltening and the films subsequently deposited as a single precursor. [Figure 2A] This figure shows the simulated current density and voltage (JV) curves under sunlight irradiation for several perovskite solar cells using the triple cation perovskite FAMACsPb(I1-xBrx)3. [Figure 2B] This shows the as-prepared triple cation perovskite FAMACsPb(I1-xBrx)3 solar cell after thermal stressing for 5 hours in an N2 atmosphere at 85°C. [Figure 3A] This figure shows the stacked XRD patterns obtained from the "as-prepared" triple cation perovskite FAMACsPb(I1-xBrx)3 after continuous light irradiation for 2 days, 7 days, and 9 days under constant sunlight. [Figure 3B] This figure shows the stacked XRD patterns obtained over continuous heat treatment periods of 2 days, 7 days, and 9 days at 85°C for the "as-prepared" triple cation perovskite FAMACsPb(I1-xBrx)3. [Figure 4] This figure shows the XRD patterns of three cation-containing perovskite formulations, namely FAMACs, FAGACs, and FAMAGACs, in their "as prepared" (fresh) state and after aging (applying thermal stress) for one week at 85°C under an N2 atmosphere. [Figure 5A] This figure shows the stacked XRD patterns obtained for the quadruple cation perovskite FAGAMACsPb(I1-xBrx)3 under constant solar irradiation in the "as prepared" state, and over periods of continuous light irradiation of 2, 7, 28, and 37 days. [Figure 5B] This figure shows the layered XRD patterns obtained over the "as prepared" state and during continuous heat treatment periods of 2, 7, 28, and 37 days at 85°C for the quadruple cation perovskite FAGAMACsPb(I1-xBrx)3. [Figure 6] This figure shows the power conversion efficiency (PCE) over time of a GA-based solar cell prepared by vacuum deposition, kept in the dark and in an N2 atmosphere at 85°C. [Modes for carrying out the invention]

[0019] The method of the present invention may include three or four evaporation sources, some of which include a mixture of multiple precursors. The resulting perovskite material ABMX3 comprises three or more different cations (located within the A site and existing as A, A', A'') and a B cation.

[0020] The present invention provides a method for reducing the number of usable source sources by co-sublimating organic halides. Preferably, one of the organic halides contains an organic monocation, and the other contains a larger organic cation (hereinafter referred to as the "cationic additive"). In another aspect of the present invention, the number of source sources can be further reduced by preparing a mixed inorganic / metal halide precursor, for example, CsI + CsBr or PbI2 + PbBr2. The method of the present invention can be divided into several steps, as shown below. The steps include co-sublimation from several source sources. Co-sublimation means that various components from each evaporation source are sublimated together or simultaneously, resulting in at least some overlap between the sublimations from each source source.

[0021] The process of the present invention is typically carried out under vacuum and generally by vacuum deposition on a substrate. This may be carried out in a vacuum chamber under an N2 atmosphere. The chamber is equipped with individual evaporation sources and may have, for example, its own independent temperature controller and shutter. Each source has a dedicated QCM sensor on it and an additional sensor placed near the substrate that can measure the overall deposition rate. The process temperature is adjusted for each chamber, for example, in the range of 100°C to 500°C, and about 10 -6 A constant pressure of mbar may also be acceptable.

[0022] Step (i) Step (i) of the method of the present invention utilizes a first evaporation source containing a mixture of co-sublimable organic halides that sublimate together (convert from solid to gas). Generally, co-sublimable organic halides have similar co-sublimation temperatures. As used in this application, the term “similar co-sublimation temperatures” refers to two different precursors (e.g., organic halides) that are placed in the same evaporation source and can deposit a final single-phase material due to the degree of proximity of their sublimation temperatures. Co-sublimation (or co-evaporation) is further described in the book “OLED Fundamentals – Materials, Devices, and Processing of Organic Light-Emitting Diodes” (edited by Daniel J. Gaspar and Evgueni Polikarpov, 2015, p. 195). It is stated that co-evaporation depends on the evaporation temperatures of two or more materials, and the ratio of each material is controlled by their respective evaporation rates.

[0023] Similar simultaneous sublimation temperatures can refer to both "compatible evaporation" and "incompatible" evaporation. "Compatible evaporation" refers to precursors that are mixed with each other to evaporate effectively as a single phase and have adjacent sublimation temperatures of 20°C (and preferably 15°C or 10°C) or less from each other. Alternatively, materials may be mixed to form a new material or alloy, which is then compatiblely evaporated from the independent substances at different temperatures.

[0024] The Handbook of Thin Film Technology (Leon I. Maissel and Reinhard Glang, 1970, Chapter 1, page 65, Chapter 6a) provides a general understanding of the term "compatible evaporation" in this field. That is, the deposition of compound films from a single vapor source requires the material to enter a gaseous state in its complete molecular form. Alternatively, if the molecules dissociate, compatible evaporation occurs if the components are equally volatile. Therefore, as mentioned above, evaporation occurs via a single phase and depends on the identity and properties of each precursor.

[0025] "Incompatible evaporation" refers to precursors present in the same crucible but not necessarily mixed to form a single substance. That is, the precursors exist as two distinct phases, which do not enter the gaseous state as complete molecules in a single vapor phase, nor do they possess the same volatility to dissociate in a compatible manner. These precursors can be heated separately, thus requiring only temperatures close to 50-150°C at their respective sublimation temperatures. During heating, the vapor flows of the two phases mix to form a first evaporation source. For example, a crucible containing two precursors can be heated over a temperature range covering the evaporation temperatures of each precursor, allowing for their co-evaporation as separate gas phases.

[0026] Preferably, in step (i), one of the organic halides contains a monocation A such as formamidinium (i.e., A is FA), and the other contains a cation A' having a larger ionic radius than the first organic cation A (preferably formamidinium (FA)). In other words, the ionic radius of organic cation A' is preferably greater than 2.53 Å (hereinafter referred to as a large monocation or large cation additive). The radii of each organic cation in a perovskite environment are found in Cheetham et al., Chem. Sci., 2015, 6, 3430 and Travis et al., Chem. Sci., 2016, 7, 4548-4556. Furthermore, Shannon et al., Acta Cryst. (1969), B25, 925-945 outlines a method for determining the effective ionic radius and provides radii for various elements such as Pb and Cs in different coordination environments. Therefore, these resources are useful for calculating the Gold-Schmidt resistance factor to estimate the stability and strain of perovskite structures.

[0027] Preferably, the A cation is a monovalent organic cation, which is co-sublimable with A' when both organic cations A and A' exist as halides (typically iodides). Preferably, when A exists as a halide, it has a sublimation temperature similar to A'. More preferably, A is selected from FA and MA. Even more preferably, A is FA. Each organic halide of the A cation typically contains a halide anion, for example, FAI.

[0028] Preferably, the A' cation is a monocation, typically a large monocation. A' is an ammonium-based organic cation, typically selected from the group consisting of guanidinium (GA), dimethylammonium (DMA), ethylammonium (EA), imidazolium (Im), phenylethylammonium (PEA), acetamidinium (Ac) and benzylammonium (BzA). Most preferably, A' is GA. Each organic halide typically contains an iodide anion, for example, GAI.

[0029] This large organic halide can be mixed with a first organic halide, such as an organic ammonium salt (e.g., by manual, high-speed mixing, or ball mill grinding), and it has been found that the two-component material can be sublimated from the same evaporation source. In a preferred embodiment, co-sublimation of the two precursors is suitable.

[0030] In another embodiment, cosublimation is incompatible. In this embodiment, the monovalent organic A cation may be methylammonium (MA).

[0031] By co-sublimating organic halides with large ammonium salts, such as guanidinium iodide (GAI), temperature-stable perovskites with multiple components can be prepared. This is unexpected because such large cations generally do not fit into the A-cation sites retained in 3D perovskites. Typically, this results in significant lattice distortion and degraded segregation of the halide.

[0032] Larger monovalent organic cations with an ionic radius greater than 2.53 Å and smaller monovalent organic cations are typically provided as halides in the first evaporation source and co-evaporate. This is facilitated by the close sublimation temperatures and similar deposition rates of the two cationic components, as shown in Table 1.

[0033] For example, a suitable combination of precursors in the first evaporation source may be FAI and GAI, or FABr and GABr.

[0034] These organic halides are all commercially available in solid powder form. These cationic salts, being in solid form, can be mixed together by any mechanical means, including manual grinding such as ball milling or speed mixing, before the evaporation step. During the evaporation stage, the two salts sublimate from solid to gas phase and can be deposited on a substrate.

[0035] As reported by Unlu et al., “Understanding Stability and Efficiency Interactions in A-Site Engineered Lead Halide Perovskites,” APL Materials 8, 070901, 2020, partial occupation of the A-site in perovskites by large cations such as GA affects the structural stabilization of the overall perovskite structure. For example, GA increases the number of hydrogen bond (HX bond) interactions more than other cations such as MA or FA. The available HX bonds interact with the inorganic backbone and directly improve thermal stability. Hydrogen bonds can also increase particle size, enhance charge carrier transport, and passivate uncoordinated halide ions within grain boundaries, thus improving the crystallinity and electronic properties of the perovskite. While large cations are expected to cause crystal distortion, MA cations localized in adjacent cavities maintain the 3D structure.

[0036] Perovskites can typically be represented by the general formula AMX3 or ABX3. The advantage of stabilizing the perovskite structure by using a large cation at the A site has been clearly demonstrated. However, vacuum deposition combining a large monovalent cation with a smaller monovalent cation has not been demonstrated, as larger cations are not expected to enter the A site of the perovskite lattice via sublimation. Vacuum deposition is a particularly attractive technique because it not only allows for better control over the quality of perovskite films, but the scalability of the technique is also advantageous for large-scale industrial production of this approach.

[0037] Therefore, the present invention demonstrates, surprisingly, that large cations can actually be co-sublimated with small monovalent organic cations such as FA to produce a thermally stabilized crystalline perovskite structure.

[0038] [Table 1] The sublimation temperatures shown in Table 1 are estimated ranges and will vary depending on the source, crucible type, type of temperature measurement, chamber, pressure, and thermocouple position. Evaporation is observed in the QCM.

[0039] Step (ii) The second evaporation source may contain a single metal halide BX2. Preferably, the second evaporation source contains two metal halides, namely BX2 and BX'2, which are usually mixed together in a crucible in the preceding step and heated under an inert atmosphere such as N2. The temperature is heated above the highest melting point of any selected precursor until they form a molten material. The molten material is then recrystallized at room temperature to form a solid mixed halide single-phase precursor. The halide stoichiometry of the final mixed halide precursor phase can be determined by the initial ratio of BX2 and BX'2. If the stoichiometrically mixed precursors form a single mixture, the subsequent compatible evaporation usually maintains the initial ratio. In another embodiment, two different metal halides may be combined in the same evaporation source without requiring the preceding step, thereby causing them to co-evaporate incompatiblely. Table 2 provides a list of film formation rates and melting points for the corresponding bromides and iodides of several preferred metal halides. All the compounds listed in Table 2 can be purchased from Sigma Aldrich in the desired solid form and, if necessary, prepared to be pre-treated and heated together to form a single precursor phase.

[0040] [Table 2] In other words, step (ii) of the method of the present invention provides a second evaporation source comprising one or more halides having formula (I). B(X y X' 1-y )2(I) Here, B is a divalent metal cation, X and X' are different halides, and 0 ≤ y < 1.

[0041] In the step preceding step (ii), it was observed that two metal halide salts react to form a new single mixed halide component, which can be sublimated as a new material. This step generally involves mixing one or more metal halides, such as BX2 and / or BX'2, and heating them in an inert atmosphere. Preferably, in this step, PbI y Br 1-y Prior to this step, PbBr2 and PbI2 are mixed and heated in an inert atmosphere.

[0042] If necessary, the B cation differs in each halide precursor, for example, BX2 and B'X'2 or BX2 and B'X2 are mixed, and the general formula is (IA)B x B' 1-x (X y X' 1-y )2 is obtained. Here, B and B' are different, and 0 <x<1および0≦y<1である。

[0043] B and B' are preferably selected from Sn and Pb.

[0044] In this case, in step (ii), the second evaporation source has two mixed metal halides selected from the following: a) Single precursor phase Pb from PbI2 and SnI2 x Sn 1-x I2 generates; b) Single precursor phase Pb from PbBr2 and SnBr2 x Sn 1-x Br2 generates; c) Single precursor phase Pb from PbI2 and SnBr2 x Sn 1-x (I 1-y Br y )2 generates; d) Single precursor phase Pb from PbBr2 and SnI2 x Sn 1-x (I 1-y Br y )2 generates.

[0045] Here, 0 <x<1かつ0≦y<1である。

[0046] In embodiments where y > 0 in step (ii), two different metal halides are mixed (i.e., the halide components are not the same).

[0047] The metal halide salts may be lead halides, such as PbI2 and PbBr2, or PbBr2 and PbCl2. The metal halide salts may be mixed at high temperature and atmospheric pressure. This is significant because it can reduce the number of evaporation sources used.

[0048] The preparation involves mixing two materials in a crucible and melting them under a nitrogen atmosphere, ambient pressure, and high temperature (>350°C) to avoid oxidation. The resulting compound consists mainly of a new mixed halide phase and can be sublimated as a single component in a co-evaporation process.

[0049] In one embodiment, the final perovskite may contain three different halide materials. The third halide may be introduced from an additional metal halide co-evaporation source. Alternatively, the third metal halide may be pre-mixed with two other metal halides in a crucible, heated under an inert atmosphere, and deposited on the substrate by compatible or incompatible evaporation. Preferably, the third halide is selected from PbI2, PbBr2, PbCl2, SnI2, SnCl2, SnBr2, or SnF2.

[0050] In another embodiment, general formula (I)B(X y X' 1-y Additional metal halide precursors having a different halide component from )2 may be included in the process as additives. These additional halide components are not present in the final perovskite formula. Preferably, the additional metal halide precursor acting as an additive is PbCl2. These additives can be appropriately incorporated into any other embodiments described herein.

[0051] Step (iii) An optional step (iii) of the method of the present invention preferably includes providing a monovalent organic halide (such as MAI) to a third evaporation source. This may be added by an optional step (iv) of a fourth evaporation source. The fourth evaporation source may include an inorganic halide such as CsI or CsBr. At least one of steps (iii) or (iv) must be present, and therefore there may be three or four evaporation sources, i.e., steps (i), (ii) and (iii), steps (i), (ii) and (iv), or steps (i), (ii), (iii) and (iv). In one embodiment, step (iii) is absent and step (iv) is present, and therefore the inorganic halide is provided to the third evaporation source to produce a triple cation perovskite.

[0052] Therefore, the perovskite material may have three or four A-site cations.

[0053] The organic portion of the organic halide in step (iii) is preferably selected from MA and FA. The halogen portion is preferably selected from I, Br and Cl. The organic halide in step (iii) is typically different from the organic halide used in step (i).

[0054] Three or four evaporation sources can be co-evaporated simultaneously to produce a final single-phase perovskite film. The term simultaneous co-evaporation means that evaporation from each source occurs substantially simultaneously. During evaporation, the plumes from each source may overlap each other by at least 10%, preferably at least 20%, more preferably at least 30%, 40%, 50%, 60%, 70%, 80%, 90%, or substantially complete (100%) overlap. If the second evaporation source contains BX2, this may be sublimated directly in co-evaporation step (ii) without any prior preliminary steps with another precursor. In one embodiment, step (iv) may produce a final material having CsI or CsBr, and being a single or mixed halide. If a final single halide material is desired, the halide component of the Cs halide may be the same as the halide component of the lead halide in step (ii). A final double mixed halide having a suitable stoichiometry is desired, and if step (ii) contains only BX2, there are two routes to obtain the mixed double halide composition. In one embodiment, the preferred stoichiometric ratio of BX2 and CsX' may be evaporated according to those steps and separate source sources, where X and X' are different halides. In another embodiment, the mixed halide component is obtained from a preceding preparation step of (iii) or (iv), and may be derived, for example, from a mixture of two inorganic halides, where one has a different halide component from the material of step (ii).

[0055] A final triple-mixed halide with a suitable stoichiometry is desired, and if step (ii) contains only BX2 and BX', there are two routes through which a mixed triple-halide composition can be formed. In one embodiment, the suitable stoichiometric ratios of BX2, BX'2 and CsX'' may be evaporated according to those steps and separate source materials, where X, X', and X'' are different halides. In another embodiment, the triple-mixed halide component is obtained from a preceding preparation step of (iii) or (iv), for example, derived from a mixture of two inorganic halides, both of which have different halide components relative to the material of step (ii).

[0056] The preferred inorganic halides, CsI and CsBr, are mixed together in a crucible and heated under an inert atmosphere such as N2 to a temperature exceeding the highest melting point of any selected precursor to form a molten material. The molten material is then recrystallized at room temperature to form a solid mixed halide single-phase precursor. The halide stoichiometry of the final mixed halide precursor phase can be determined by the initial ratio of CsBr and CsI. Table 3 provides the melting temperatures and deposition rates of the CsI and CsBr compounds, highlighting the proximity and equal deposition rates of their sublimation temperatures. Thus, the Cs mixed halide precursor occupies a third evaporation source, co-sublimating with the first and second evaporation sources.

[0057] Furthermore, a fourth evaporation source may be introduced if necessary. The fourth evaporation source may contain an inorganic halide such as CsI or CsBr, and the third evaporation source may contain an organic halide selected from organic monocations such as MA and FA cations. As a result, none of the precursor organic cations in this method will be the same.

[0058] In another embodiment of the present invention, the second evaporation source in step (ii) may instead consist of the preparation of two mixed metal-mixed halide reagents, such as BX2 and B'X'2. For example, PbI2 and SnBr2, or similarly PbBr2 and SnI2, may be mixed in a crucible and melted under an inert atmosphere such as N2 at a temperature corresponding to the highest melting point of any precursor to form a molten material. The molten material is then recrystallized at room temperature to form a solid mixed halide-mixed metal single-phase precursor. The stoichiometry of the halide and metal in the final precursor phase can be determined by the initial ratio of BX2 to B'X'2.

[0059] In the above embodiment, the third or fourth evaporation source may include an inorganic halide such as CsI or CsBr, or an organic halide selected from MA and FA cations. This ensures that the precursor organic cations are not all the same.

[0060] Cs salts can be sourced directly from standard suppliers in powder form, pre-treated for forming a single precursor phase.

[0061] Step (iv) Step (iv) may include the introduction of an inorganic halide component. Step (iii) may or may not be present, and therefore there may be three or four evaporation sources. If four evaporation sources are used as required, the inorganic halide is provided to the fourth evaporation source and the organic halide is provided to the third evaporation source. All A cations are different from one another in the final composition.

[0062] The inorganic portion of the inorganic halide component is preferably selected from Cs and Rb, and is preferably Cs.

[0063] Therefore, the method may include four evaporation sources, in step (ii) BX2 is provided as an evaporation source, in step (iv) a mixed Cs halide is provided as a fourth evaporation source, and an organic halide is provided as a third evaporation source.

[0064] In this embodiment, a quadruple-cationic perovskite may be formed using a fourth evaporation source. This includes an organic halide selected from organic monocations such as MA, FA, and EA cations, with MA being preferred. This ensures that none of the precursor organic cations are the same.

[0065] In yet another embodiment, the second evaporation source may consist of the preparation of BX2 and B'X2, yielding the same halide precursor of the mixed metal. For example, any two of PbCl2, PbBr2, and PbI2, or any two of SnCl2, SnF2, SnBr2, and SnI2, can be mixed in a crucible and melted at a temperature corresponding to the highest melting point of any precursor under an inert atmosphere such as N2 to form a molten material. The molten material is then recrystallized at room temperature to form a solid mixed metal single-phase precursor. The metallostoichiometry of the final precursor phase can be determined by the initial ratio of BX2 to B'X2.

[0066] Similar to step (iii), where the second evaporation source simply comprises a single halide, step (iv) may comprise CsI or CsBr to produce a final material of a single or mixed halide. If a final single halide material is desired, the halide component of the Cs halide is the same as the halide component of the lead halide in step (ii). If a final mixed halide with a suitable stoichiometry is desired, there are two routes through which a mixed halide composition can be obtained. In one embodiment, the suitable stoichiometric ratio of BX2 and CsX' may be evaporated in their separate steps and chambers, where X and X' are different halides. In another embodiment, the mixed halide component is obtained from a preceding preparation step in (iv), for example, from a mixture of inorganic halides.

[0067] The preferred inorganic halides, CsI and CsBr, may be mixed in a crucible and heated under an inert atmosphere such as N2 to a temperature exceeding the highest melting point of any selected precursor until a molten material is formed. The molten material is then recrystallized at room temperature to form a solid mixed halide single-phase precursor. The halide stoichiometry of the final mixed halide precursor phase can be determined by the initial ratio of CsBr and CsI. Thus, the Cs mixed halide precursor occupies a third (or fourth) evaporation source, which co-sublimes with the first and second, forming a triple or quadruple cation bihalide perovskite film on the substrate.

[0068] Additionally, if necessary, another evaporation source containing an organic halide selected from the MA cation (in step (iii)) may be used, so that none of the precursor organic cations are the same.

[0069] [Table 3] The temperatures listed in Tables 1 to 3 are for reference purposes only and may change as the process scales up. Similarly, the deposition rate of each precursor is greatly influenced by the operating temperature and pressure and may therefore change during scale-up (T. Neubert, M. Vergohl, Optical Thin Films and Coatings, 2013).

[0070] In all embodiments, the multicomponent perovskite has a preferred thickness of 50 to 2000 nm, preferably 100 to 1500 nm. This is governed by the deposition rate of each precursor under vacuum conditions below atmospheric pressure. Once the perovskite film is deposited on the substrate, the film is then annealed at a temperature in the range of 50 to 300°C for, for example, 1 minute to 6 hours, to promote and ensure the uniform morphology of the crystalline film. This ensures that large doped cations are well introduced into the perovskite lattice. Specific process conditions may affect the amount of large cations that enter the lattice. However, within the recommended temperature range, at least some introduction of large cations can be expected. Also, in some cases, the large cations act as passivating additives for defects at grain boundaries and on the surface, and are therefore not incorporated into the final perovskite formula. These passivating additives can be suitably incorporated into any other embodiments described herein.

[0071] material Typically, the method of the present invention involves the formation of a thin-film perovskite material, the band gap of which is usually in the range of 1.1 eV to 2.5 eV.

[0072] The perovskite material is preferably a mixed halide material, that is, it contains two or more different halides. This may include two types of halides, or it may contain three different halide anions.

[0073] Typically, the perovskite material formed by the method of the present invention has general formula (II): A a A' b A'' c A''' d B x B' 1-x (X y X' 1-y )3 Here, A is a first monovalent organic cation that can co-sublimate with A' when both organic cations A and A' are present as halides (preferably iodides), A' is a second monovalent organic cation, A'' and A''' are, independently, monovalent inorganic cations or other monovalent organic cations. Here, all A cations are distinct from one another, and at least three of these exist. 0 <a<1、 0 <b<1、 0 <c<1、 0≦d<1, a+b+c+d=1, 0≦x<1 and 0≦y<1, B and B' are independently divalent metal cations. X and X' are halide anions.

[0074] In a preferred embodiment, the perovskite material formed by the method of the present invention has the following general formula: A a A' b A'' c A''' d B x B' 1-x (X y X' 1-y )3(III) Here, A is a monovalent organic cation that, when present in a halide, can co-sublimate with A'. A' is a monovalent organic cation with an ionic radius greater than 2.53 Å. A'' is a monovalent inorganic cation or a monovalent organic cation. A''' is a monovalent inorganic cation or a monovalent organic cation. Here, all A cations are distinct from each other. 0 <a<1、 0 <b<1、 0 <c<1、 0≦d<1, a+b+c+d=1, 0 ≤ x < 1, 0 ≤ y < 1.

[0075] In both of these embodiments, preferably 0 < y < 1, that is, the halide components are different.

[0076] When A is present as a halide, preferably an iodide, it is a monovalent organic cation having a sublimation temperature similar to that of A'. The halide moiety is selected from X or X' as in the final product of formula (II).

[0077] In a preferred embodiment, A is FA. In a more preferred embodiment, A' is selected from guanidinium (GA), dimethylammonium (DMA), benzylammonium (BzA), ethylammonium (EA), imidazolium (Im), acetamidinium (Ac), and phenylethylammonium (PEA), and preferably, A' is GA.

[0078] Also, A' and A'' are different from each other and may be selected from any of the following: (i) A group of organic cations usually including MA, FA, EA, preferably MA, and / or (ii) Cesium ions.

[0079] Also, the X and X' anions are different from each other and are selected from the group of halides including Cl, Br, and I, and preferably, the halide is I and / or Br.

[0080] The B cation is Pb 2+ and Sn 2+ selected from, and B' is different from B but is selected from Pb 2+ and Sn 2+ selected from.

[0081] In one embodiment, the method may have three evaporation sources. In step (ii) of the method, one or more metal halides are provided to a single source, and in step (iii) of the method, either an inorganic halide or an organic halide is provided to a third evaporation source, and a triple-cation perovskite is provided.

[0082] Such perovskites may be selected from the following formulas: FA a GA b MA c Pb(I y Br 1-y )3, FA a GA b Cs c Pb(I y Br 1-y )3, MA a GA b Cs c Pb(I y Br 1-y )3, FA a BzA b MA c Pb(I y Br 1-y )3, FA a BzA b Cs c Pb(I y Br 1-y )3, MAaBzA b Cs c Pb(I y Br 1-y )3, FA a DMA b Cs c Pb(I y Br 1-y )3, FA a DMA b MA c Pb(I y Br 1-y )3, MA a DMA b Cs c Pb(I y Br 1-y )3, FA a GA b MA c Sn(Iy Br 1-y )3、FA a GA b Cs c Sn(I y Br 1-y )3、MA a GA b Cs c Sn(I y Br 1-y )3、FA a BzA b MA c Sn(I y Br 1-y )3、FA a BzA b Cs c Sn(I y Br 1-y )3、MA a BzA b Cs c Sn(I y Br 1-y )3、FA a DMA b Cs c Sn(I y Br 1-y )3、FA a DMA b MA c Sn(I y Br 1-y )3、MA a DMA b Cs c Sn(I y Br 1-y )、FA a Im b Cs c Pb(I y Br 1-y )3、FA a Im b Cs c Sn(I y Br 1-y )3、FA a PEA b Cs c Pb(I y Br 1-y )3、FA a Ac b Cs c Pb(I y Br 1-y )3、FAa Ac b Cs c Sn(I) y Br 1-y )3、FA a BzA b AND c Pb(I) y Br 1-y )3、FA a BzA b AND c Sn(I) y Br 1-y )3、FA a I am b AND c Pb(I) y Br 1-y )3、FA a I am b AND c Sn(I) y Br 1-y )3、FA a TO BE b AND c Pb(I) y Br 1-y )3、FA a TO BE b AND c Sn(I) y Br 1-y )3、FA a EA b Cs c Pb(I) y Br 1-y )3、FA a EA b AND c Pb(I) y Br 1-y )3、FA a EA b Cs c Sn(I) y Br 1-y )3、FA a EA b AND c Sn(I) y Br 1-y )3、MA a EA b Cs c Pb(I) y Br 1-y )3、MA a EA b Csc Sn(I y Br 1-y )3. Here, 0 <a<1、0<b<1、0<c<1、a+b+c=1、0≦y<1である。

[0083] In another embodiment, the method may have three evaporation sources, in step (ii) of the method, a mixture of metal halides, each having a different metal component, is provided to a single evaporation source, and in step (iii) or (iv) of the method, either an inorganic halide or an organic halide is provided to a third evaporation source to provide a triple-cation mixed metal perovskite.

[0084] Such perovskites may be selected from the following formulas: FA a GA b MA c Pb x Sn 1-x (I y Br 1-y )3, FA a GA b Cs c Pb x Sn 1-x (I y Br 1-y )3, MA a GA b Cs c Pb x Sn 1-x (I y Br 1-y )3, FA a BzA b MA c Pb x Sn 1-x (I y Br 1-y )3, FA a BzA b Cs c Pb x Sn 1-x (I y Br 1-y )3, MA a BzA b Cs c Pb x Sn1-x (I y Br 1-y )3、FA a DMA b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a DMA b MA c Pb x Sn 1-x (I y Br 1-y )3、MA a DMA b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a Im b MA c Pb x Sn 1-x (I y Br 1-y )3、FA a Im b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a PEA b MA c Pb x Sn 1-x (I y Br 1-y )3、FA a PEA b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a Ac b MA c Pb x Sn 1-x (I y Br 1-y )3、FA a Ac b Cs c Pb x Sn 1-x (I yBr 1-y )3, FA a EA b Cs c Pb x Sn 1-x (I y Br 1-y )3, FA a EA b MA c Pb x Sn 1-x (I y Br 1-y )3, MA a EA b Cs c Pb x Sn 1-x (I y Br 1-y )3; Here, 0 <a<1、0<b<1、0<c<1、a+b+c=1、0<x<1、0≦y<1である。

[0085] In another embodiment, the method may have four evaporation sources, in step (ii) of the method, one or more metal halides are supplied to a single evaporation source, and in steps (iii) and (iv) of the method, an inorganic halide is supplied to a fourth evaporation source and an organic halide is supplied to a third evaporation source to produce a quadruple cation perovskite material.

[0086] Such perovskites may be selected from the following formulas: FA a GA b MA c Cs d Pb(I y Br 1-y )3, FA a EA b MA c Cs d Pb(I y Br 1-y )3, FA a BzA b MA c Cs d Pb(I y Br 1-y )3, FA a DMA b MAc Cs d Pb(I y Br 1-y )3、FA a GA b MA c Cs d Sn(I y Br 1-y )3、FA a EA b MA c Cs c Sn(I y Br 1-y )3、FA a BzA b MA c Cs d Sn(I y Br 1-y )3、FA a DMA b MA c Cs d Sn(I y Br 1-y )3、FA a Im b MA c Cs d Pb(I y Br 1-y )3、FA a Im b MA c Cs d Sn(I y Br 1-y )3、FA a PEA b MA c Cs d Pb(I y Br 1-y )3、FA a PEA b MA c Cs d Sn(I y Br 1-y )3、FA a Ac b MA c Cs d Pb(I y Br 1-y )3、FA a Ac b MA c Cs d Sn(I y Br1-y )3; Here, 0 <a<1、0<b<1、0<c<1、0<d<1、a+b+c+d=1、0≦y<1である。

[0087] In another embodiment, the method may have four evaporation sources, in step (ii) of the method, a mixture of metal halides having different metal components is provided to a single evaporation source, and in step (iii) of the method, an inorganic halide is provided to a third evaporation source, and an organic halide is provided to a fourth evaporation source, thereby obtaining a quadruple-cation mixed metal perovskite material.

[0088] Such perovskites may be selected from the following formulas: FA a GA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a BzA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a EA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a DMA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a Im b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a PEAb MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a Ac b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3; Here, 0 <a<1、0<b<1、0<c<1、0<d<1、a+b+c+d=1、0<x<1、0≦y<1である。

[0089] In yet another aspect of the present invention, novel perovskites of the following general formula are provided: MA a GA b Cs c Pb(I y Br 1-y )3, FA a BzA b MA c Pb(I y Br 1-y )3, FA a BzA b Cs c Pb(I y Br 1-y )3, MA a BzA b Cs c Pb(I y Br 1-y )3, MA a DMA b Cs c Pb(I y Br 1-y ), FA a GA b MA c Sn(I y Br 1-y )3, FA a GA b Cs c Sn(I y Br 1-y )3, MA a GA b Cs c Sn(Iy Br 1-y )3、FA a BzA b MA c Sn(I y Br 1-y )3、FA a BzA b Cs c Sn(I y Br 1-y )3、MA a BzA b Cs c Sn(I y Br 1-y )3、FA a DMA b Cs c Sn(I y Br 1-y )3、FA a DMA b MA c Sn(I y Br 1-y )3、MA a DMA b Cs c Sn(I y Br 1-y )、FA a Im b Cs c Sn(I y Br 1-y )3、FA a PEA b Cs c Pb(I y Br 1-y )3、FA a PEA b Cs c Sn(I y Br 1-y )3、FA a Ac b Cs c Sn(I y Br 1-y )3、FA a BzA b MA c Pb(I y Br 1-y )3、FA a BzA b MA c Sn(I y Br 1-y )3、FAa I am b AND c Pb(I) y Br 1-y )3、FA a I am b AND c Sn(I) y Br 1-y )3、FA a TO BE b AND c Pb(I) y Br 1-y )3、FA a TO BE b AND c Sn(I) y Br 1-y )3、FA a EA b Cs c Sn(I) y Br 1-y )3、FA a EA b AND c Sn(I) y Br 1-y )3、MA a EA b Cs c Pb(I) y Br 1-y )3、MA a EA b Cs c Sn(I) y Br 1-y )3、FA a EN b AND c Pb x Sn 1-x (I y Br 1-y )3、FA a EN b Cs c Pb x Sn 1-x (I y Br 1-y )3、MA a EN b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a BzA b ANDc Pb x Sn 1-x (I y Br 1-y )3、FA a BzA b Cs c Pb x Sn 1-x (I y Br 1-y )3、MA a BzA b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a DMA b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a DMA b MA c Pb x Sn 1-x (I y Br 1-y )3、MA a DMA b CsPb x Sn 1-x (I y Br 1-y )、FA a Im b MA c Pb x Sn 1-x (I y Br 1-y )3、FA a Im b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a PEA b MA c Pb x Sn 1-x (I y Br 1-y )3、FA a PEA b Cs c Pb x Sn1-x (I y Br 1-y )3、FA a Ac b MA c Pb x Sn 1-x (I y Br 1-y )3、FA a Ac b Cs c Pb x Sn 1-x (I y Br 1-y )3; ここで、0<a<1、0<b<1、0<c<1、0<d<1、a+b+c=1、0<x<1、0<y<1であり、 FA a EA b MA c Cs d Pb(I y Br 1-y )3、FA a BzA b MA c Cs d Pb(I y Br 1-y )3、FA a DMA b MA c Cs d Pb(I y Br 1-y )3、FA a GA b MA c Cs d Sn(I y Br 1-y )3、FA a EA b MA c Cs c Sn(I y Br 1-y )3、FA a BzA b MA c Cs d Sn(I y Br 1-y )3、FA a DMA b MA c Cs d Sn(I y Br 1-y)3、FA a Im b MA c Cs d Pb(I y Br 1-y )3、FA a Im b MA c Cs d Sn(I y Br 1-y )3、FA a PEA b MA c Cs d Sn(I y Br 1-y )3、FA a Ac b MA c Cs d Pb(I y Br 1-y )3、FA a Ac b MA c Cs d Sn(I y Br 1-y )3、FA a GA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3、FA a BzA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3、FA a EA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3、FA a DMA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3、FA a Im bMA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a PEA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a Ac b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3; Here, 0 <a<1、0<b<1、0<c<1、0<d<1、a+b+c+d=1、0<x<1、0<y<1である。

[0090] In yet another embodiment of the present invention, a semiconductor device is provided having a photoactive layer comprising an organic-inorganic metal halide perovskite material formed according to a first aspect of the present invention.

[0091] In another embodiment, the semiconductor device is a photovoltaic device having a photoactive region, the photoactive region having a thin film of perovskite material formed according to a first aspect of the present invention, the thickness of the thin film of perovskite material being in the range of 50 to 2000 nm, preferably in the range of 100 nm to 1500 nm. Furthermore, the photoactive region may include an n-type region having at least one n-type layer and a layer of perovskite material in contact with the n-type region.

[0092] The photovoltaic device may have an n-type region containing at least one n-type layer, a p-type region containing at least one p-type layer, and a layer of perovskite material disposed between the n-type region and the p-type region.

[0093] In another embodiment of the present invention, a multijunction photovoltaic device is provided, which has two or more subcells, the first subcell having the aforementioned photovoltaic device having a band gap between 1.1 and 2.5 eV, and further subcells having a second photoactivity with a complementary band gap.

[0094] In one embodiment of the present invention, the photovoltaic device may be a single-junction device. In another embodiment, the photovoltaic device may be a multi-junction device, and depending on the shape of the device, one or more of the upper, middle, or lower subcells may have the perovskite described in the application in an all-perovskite, perovskite-Si, perovskite-CIGS, perovskite-CuZnSnSSe tandem cell, perovskite-CuZnSnS tandem cell, or perovskite-CdTe heterojunction device.

[0095] In another embodiment of the present invention, a photoelectronic device is provided comprising a perovskite material formed according to a first aspect of the present invention.

[0096] In some embodiments, the optoelectronic device may include a substrate. The substrate may have a flat surface. Alternatively, the substrate may have a root mean square roughness (R) of 50 nm or more. rms The surface may be textured, having ) . The substrate material may be selected from glass such as fluorine-doped tin oxide (FTO), indium tin oxide (ITO), or silicon (Si).

[0097] Detailed description definition As used in this application, the term "photoactive" refers to a region, layer, or material that can respond photoelectrically to light. Thus, a photoactive region, layer, or material can absorb the energy carried by photons of light, and as a result generate electricity (for example, by generating either electron-hole pairs or excitons).

[0098] As used in this application, the term "perovskite" refers to a material having a three-dimensional crystalline structure related to the structure of CaTiO3, or a material containing a layer of material having a structure related to the structure of CaTiO3. The structure of CaTiO3 is represented by the formula ABX3, where A and B are cations of different sizes, and X is an anion. In a single cell, the A cation is at (0,0,0), the B cation is at (1 / 2,1 / 2,1 / 2), and the X anion is at (1 / 2,1 / 2,0). The A cation is usually larger than the B cation. It will be apparent to those skilled in the art that when A, B, and X are changed, the structure of the perovskite material is distorted from the structure adopted by CaTiO3 to a less symmetrical, distorted structure due to the different ion sizes. Furthermore, the symmetry is lower when the material contains a layer of material containing a structure related to the structure of CaTiO3. Materials containing layers of perovskite material are well known. For example, the structure of a material employing a K2NiF4 type structure includes a layer of perovskite material. It will be apparent to those skilled in the art that perovskite material can be represented by the general formula [A][B][X]3, where [A] is at least one cation, [B] is at least one cation, and [X] is at least one anion. If the perovskite contains two or more A cations, different A cations may be distributed at the A sites in a regular or disordered manner. If the perovskite contains two or more B cations, different B cations may be distributed on the B sites in a regular or disordered manner. If the perovskite contains two or more X anions, different X anions may be distributed at the X sites in a regular or disordered manner. The symmetry of a perovskite containing two or more A cations, two or more B cations, or two or more X cations is often lower than that of CaTiO3.

[0099] As previously stated, the term “perovskite” as used in this application refers to (a) a material having a three-dimensional crystalline structure related to the structure of CaTiO3, or (b) a material comprising layers of a material having a structure related to the structure of CaTiO3. Both of these categories of perovskites may be used in devices according to the present invention, but in certain situations, it is preferable to use perovskites of the first category (a), i.e., perovskites having a three-dimensional (3D) crystalline structure. Such perovskites typically comprise a 3D network of perovskite unit cells without separation between layers. On the other hand, perovskites of the second category (b) include perovskites having a two-dimensional (2D) layered structure. Perovskites having a two-dimensional layered structure may have layers of perovskite unit cells separated by (intercalated) molecules. An example of such a two-dimensional layered perovskite is [2-(1-cyclohexenyl)ethylammonium]2PbBr4. 2D layered perovskites tend to have high exciton binding energies, which are significant for the formation of bound electron-hole pairs (excitons) rather than free charge carriers under photoexcitation. The bound electron-hole pairs cannot move sufficiently and cannot reach p-type or n-type contacts to subsequently move (ionize) and generate free charge. As a result, the exciton binding energy must be overcome to generate free charge, which represents an energy cost to the charge generation process, leading to lower voltage and lower efficiency in photovoltaic cells. On the other hand, perovskites with a 3D crystal structure tend to have much lower exciton binding energies (on the order of thermal energy) and can therefore directly generate free carriers following photoexcitation. Accordingly, the perovskite semiconductor used in the devices and processes of the present invention is preferably a perovskite of the first category (a), i.e., a perovskite having a three-dimensional crystal structure. This is particularly preferred when the optoelectronic device is a photovoltaic device.

[0100] The perovskite material used in this invention can absorb light, thereby generating free charge carriers. Therefore, the perovskite used is a light-absorbing perovskite material. However, it will also be understood by those skilled in the art that a perovskite material is a perovskite material that can emit light by accepting both electron and hole charges, and then recombine to emit light. Therefore, the perovskite used may be an emitting perovskite.

[0101] As those skilled in the art will understand, the perovskite material used in the present invention may be a perovskite that functions as an n-type electron transport semiconductor when photodoped. Alternatively, it may be a perovskite that functions as a p-type hole transport semiconductor when photodoped. Thus, the perovskite may be n-type, p-type, or an intrinsic semiconductor. In a preferred embodiment, the perovskite used functions as an n-type electron transport semiconductor when photodoped. The perovskite material exhibits bipolar charge transport and therefore functions as both an n-type and a p-type semiconductor. In particular, the perovskite may function as both an n-type and a p-type semiconductor depending on the type of junction formed between the perovskite and the adjacent material.

[0102] Typically, the perovskite semiconductor used in this invention is a photosensitive material, that is, a material capable of both light generation and charge transport.

[0103] As used in this application, the term “mixed halide” refers to a compound comprising at least two different halides. The term “halide” refers to an anion of an element selected from Group 17 of the periodic table, i.e., a halogen anion. Typically, a halide anion refers to a fluoride anion, chloride anion, bromide anion, iodide anion, or astatinide anion.

[0104] As used in this application, the term "metal halide perovskite" refers to a perovskite whose general formula includes at least one metal cation and at least one halide anion. As used in this application, the term "organometallic halide perovskite" refers to a metal halide perovskite whose general formula includes at least one organic cation.

[0105] The term “organic material” has the common meaning in the art. Typically, an organic material refers to a material comprising one or more compounds containing carbon atoms. As will be understood by those skilled in the art, an organic compound may also contain carbon atoms covalently bonded to another carbon atom, or a hydrogen atom, or a halogen atom, or a chalcogen atom (e.g., an oxygen atom, a sulfur atom, a selenium atom, or a tellurium atom). Those skilled in the art will understand that the term “organic compound” usually does not include ionic compounds, such as carbides.

[0106] The term "organic cation" refers to a cation containing carbon. A cation may also contain other elements; for example, a cation may contain hydrogen, nitrogen, or oxygen. The term "inorganic cation" refers to a cation that is not an organic cation. By default, the term "inorganic cation" refers to a cation that does not contain carbon.

[0107] As used in this application, the term "semiconductor" refers to a material having an electrical conductivity intermediate between that of a conductor and a dielectric. The semiconductor may be an n-type semiconductor, a p-type semiconductor, or an intrinsic semiconductor.

[0108] As used in this application, the term “n-type” refers to a region, layer, or material containing an exogenous semiconductor with a higher concentration of electrons than holes. Therefore, in n-type semiconductors, electrons are majority carriers and holes are minority carriers; thus, these are electron-transport materials. Accordingly, as used in this application, the term “n-type region” refers to a region of one or more electron-transport (i.e., n-type) materials. Similarly, the term “n-type layer” refers to a layer of electron-transport (i.e., n-type) materials. Electron-transport (i.e., n-type) materials may be a single electron-transport compound or elemental material, or a mixture of two or more electron-transport compounds or elemental materials. Electron-transport compounds or elemental materials may be undoped or doped with one or more dopant elements.

[0109] As used in this application, the term "p-type" refers to a region, layer, or material containing an exogenous semiconductor with a higher concentration of holes than electrons. In p-type semiconductors, holes are the majority carriers and electrons are the minority carriers; therefore, these are hole-transport materials. Accordingly, as used in this application, the term "p-type region" refers to a region of one or more hole-transport (i.e., p-type) materials. Similarly, the term "p-type layer" refers to a layer of hole-transport (i.e., p-type) materials. The hole-transport (i.e., p-type) material may be a single hole-transport compound or elemental material, or a mixture of two or more hole-transport compounds or elemental materials. The hole-transport compound or elemental material may be undoped or doped with one or more dopant elements.

[0110] As used in this application, the term "band gap" represents the energy difference between the upper part of the valence band and the lower part of the conduction band in a material. Those skilled in the art can easily measure the band gap of a material without performing excessive experiments.

[0111] As used in this application, the term “layer” refers to any structure that is substantially layered (for example, extending substantially in two perpendicular directions, but with its extension restricted in a third perpendicular direction). A layer may have a thickness that varies over the range of the layer. Typically, a layer has a nearly constant thickness. As used in this application, the “thickness” of a layer refers to the average thickness of the layer. The thickness of a layer may be readily measured, for example, by using a microscope such as an electron microscope on a cross-section of the film, or by surface profilometry using a stylus profilometer.

[0112] As used in this application, the term "porous" refers to a material in which pores are arranged internally. Therefore, for example, in a porous material, a pore is the volume of a portion of the material body where no material exists. Individual pores may be the same size or different sizes. The size of a pore is defined as "pore size." In most phenomena involving porous solids, the limiting size of a pore is the size of its minimum dimension, and unless there is any further clarity, it is referred to as the width of the pore (i.e., the width of a slit-shaped pore, the diameter of a cylindrical or spherical pore, etc.). To avoid misunderstandings of scale changes when comparing cylindrical and slit-shaped pores, the diameter of a cylindrical pore should be used as "pore width" (Rouquerol, J. et al., (1994) Recommendations for the Characterization of Porous Solids (Technical Report). Pure and Applied Chemistry, 66(8)). The following distinctions and definitions are adopted in a previous IUPAC document (J. Haber. (1991)). Manual for Catalyst Characterization (Recommendation 1991). Pure and Applied Chemistry: Micropores have a width (i.e., pore size) of less than 2 nm, mesopores have a width (i.e., pore size) of 2 nm to 50 nm, and macropores have a width (i.e., pore diameter) greater than 50 nm. Nanopores may also be considered to have a width (i.e., pore size) of less than 1 nm.

[0113] Pores in a material can include "closed" pores and open pores. A closed pore is a pore in a material that is an unconnected cavity; that is, it is isolated within the material, not connected to any other pores, and therefore inaccessible by the fluid to which the material is exposed. An "open pore," on the other hand, is accessible by such a fluid. The concepts of open and closed porosity are discussed in detail by J. Rouquerol et al.

[0114] Therefore, open porosity represents the proportion of the total volume of porous material in which fluid flow can effectively occur. Thus, closed pores are excluded. The term "open porosity" is interchangeable with the terms "connected porosity" and "effective porosity," and is generally abbreviated simply as "porosity" in the art. Therefore, the term "without open porosity" as used in this application refers to a material that does not have effective porosity. Thus, a material without open porosity typically does not have either macropores or mesopores. However, a material without open porosity may include micropores and nanopores. Such micropores and nanopores are extremely small and usually do not have a negative effect on materials in which low porosity is desired.

[0115] Furthermore, polycrystalline materials are solids composed of a large number of separate crystals or particles, and grain boundaries exist at the interfaces between any two crystals or particles in the material. Thus, polycrystalline materials can have both interparticle / interstitial porosity and intraparticle / internal porosity. As used in this application, the terms “interparticle porosity” and “interstitial porosity” refer to pores (i.e., grain boundaries) between crystals or particles in a polycrystalline material, while the terms “intraparticle porosity” and “internal porosity” refer to pores inside individual crystals or particles in a polycrystalline material. On the other hand, single crystals or single-crystal materials are solids in which the crystal lattice is continuous and does not collapse throughout the entire volume of the material, and there are no grain boundaries and no interparticle / interstitial porosity.

[0116] As used in this application, the term "compact layer" refers to a layer that does not have mesoporosity or macroporosity. The compact layer may occasionally have microporosity or nanoporosity.

[0117] Therefore, the term "scaffolding material" as used in this application refers to a material that can function as a support for another material. Therefore, the term "porous scaffolding material" as used in this application refers to a material that is porous in itself and can function as a support for another material.

[0118] As used in this application, the term "transparent" refers to a material or object through which visible light can pass with little obstruction, and through which objects behind it can be clearly seen. Accordingly, as used in this application, the term "translucent" refers to a material or object that has a degree of transmittance (or equivalently referred to as transmittance) with respect to visible light between transparent and opaque materials or objects. Typically, transparent materials have an average transmittance of about 100%, or 90 to 100%, with respect to visible light (generally light with wavelengths from 370 to 740 nm). Typically, opaque materials have an average transmittance of about 0%, or 0 to 5%, with respect to visible light. Translucent materials or objects typically have an average transmittance of 10 to 90%, typically 40 to 60%, with respect to visible light. Unlike many translucent objects, translucent objects do not usually distort or blur images. Light transmittance can be measured by conventional methods, for example, by comparing the intensity of incident light with the intensity of transmitted light.

[0119] As used in this application, the term “electrode” refers to a conductive material or object through which electric current flows in and out of a material, substance, or region. As used in this application, the term “negative electrode” refers to an electrode through which electrons are emitted from a material or object (i.e., an electron collecting electrode). The negative electrode is typically referred to as the “anode.” As used in this application, the term “positive electrode” refers to an electrode through which holes are emitted from a material or object (i.e., a hole collecting electrode). The positive electrode is typically referred to as the “cathode.” In a photovoltaic device, electrons flow from the positive electrode / cathode to the negative electrode / anode, and holes flow from the negative electrode / anode to the positive electrode / cathode.

[0120] As used in this application, the term “front electrode” refers to an electrode provided on the side or surface of a photovoltaic device that is intended to be exposed to sunlight. Therefore, the front electrode is typically required to be transparent or translucent so that light can pass through the electrode and reach a photoactive layer located beneath it. Accordingly, as used in this application, the term “back electrode” refers to an electrode provided on the side or surface of a photovoltaic device opposite to the side or surface intended to be exposed to sunlight.

[0121] The term "charge transporter" refers to a region, layer, or material through which charge carriers (i.e., particles that carry charge) can move freely. In semiconductors, electrons act as mobile negative charge carriers, and holes act as mobile positive charge carriers. Therefore, the term "electron transporter" refers to a region, layer, or material through which electrons can easily flow and which typically reflects holes (holes are the absence of electrons, which are considered mobile positive charge carriers in semiconductors). Conversely, the term "hole transporter" refers to a region, layer, or material through which holes can easily flow and which typically reflects electrons.

[0122] As used in this application, the term "volatile compound" refers to a compound that is easily removed by evaporation or decomposition. For example, a compound that is easily removed by evaporation or decomposition at a temperature of 150°C or below, or, for example, 100°C or below, is a volatile compound. Furthermore, "volatile compounds" also include compounds that are easily removed by evaporation via decomposition products. Therefore, a volatile compound X may easily evaporate by the evaporation of the X molecule, or it may easily evaporate by decomposing to form two compounds Y and Z that are easily evaporated. For example, an ammonium salt is a volatile compound and may volatilize as an ammonium salt molecule or as a decomposition product, such as an ammonium and hydrogen compound (e.g., hydrogen halide). Therefore, a volatile compound X may have a relatively high vapor pressure (e.g., 500 Pa or more) or a relatively high decomposition pressure (e.g., 500 Pa or more with respect to one or more decomposition products), the latter of which is also called dissociation pressure.

[0123] As used in this application, the term “conform” refers to an object that is substantially identical in form or shape to another object. Accordingly, as used in this application, a “conformal layer” refers to a layer of material that conforms to the contour of the surface on which the layer is formed. In other words, the form of the layer is such that the thickness of the layer is substantially constant over most of the interface between the layer and the surface on which it is formed.

[0124] As used in this application, the term co-evaporation refers to the process in which two or more materials or mixtures of materials are heated in separate source chambers, evaporation is initiated, and then simultaneously deposited onto a substrate. This term is interchangeable with the term "co-sublimation."

[0125] As used in this application, the term “large organic cation” refers to a monovalent organic cation having an ionic radius greater than 2.53 Å that can occupy the A-site of a perovskite structure. As used in this application, the term “additive” refers to a component added to a perovskite formulation that can improve the photoelectronic properties of the perovskite material and the performance characteristics of the corresponding perovskite solar cell device. Therefore, as used in this application, the term “large organic cation additive” refers to an organic cation having an ionic radius greater than 2.53 Å that can occupy the A-site of a perovskite structure and thereby improve the characteristics of the perovskite material and / or perovskite device.

[0126] The term "optoelectronic device" includes photovoltaic devices, photodiodes (including solar cells), phototransistors, photomultiplier tubes, photoresistors, and light-emitting diodes, etc.

[0127] Photovoltaic devices The perovskite material of the present invention may be used in semiconductor devices, preferably photovoltaic devices. The perovskite material is advantageously configured to function as a light absorber / photosensitizer within the photoactive region of a photovoltaic device.

[0128] The photoactive region may include a thin film of perovskite material, preferably with a thickness of 50 nm to 2000 nm, more preferably 100 nm to 1500 nm, and more preferably 300 to 1200 nm.

[0129] The photoactive region may have an n-type region containing at least one n-type layer and a layer of perovskite material in contact with the n-type region.

[0130] The photoactive region may have an n-type region containing at least one n-type layer, a p-type region containing at least one p-type layer, and a layer of perovskite material disposed between the n-type region and the p-type region.

[0131] The photoactive region may include a layer of perovskite material without open porosity. The layer of perovskite material may form a planar heterojunction with one or both of the n-type and p-type regions.

[0132] Alternatively, though less preferable, the layer of perovskite material may be in contact with a porous scaffold material positioned between the n-type and p-type regions. The porous scaffold material may have, or be essentially composed of, any dielectric and semiconductor / charge transport material. The layer of perovskite material is then positioned within the pores of the porous scaffold material and may conform to the surface of the porous scaffold material. Alternatively, the layer of perovskite material may fill the pores of the porous scaffold material, forming a cap layer on top of the porous scaffold material. The cap layer consists of a layer of photoactive material without open porosity.

[0133] The photovoltaic device further comprises a first electrode and a second electrode, wherein a photoactive region is positioned between the first and second electrodes, the first electrode in contact with the n-type region of the photoactive region, and the second electrode in contact with the p-type region of the photoactive region. The first and second electrodes may be made of transparent or light-transmitting conductive materials, and the second electrode may include a metal or a second light-transmitting conductive material. The first electrode is an electron collecting electrode, and the second electrode is a hole collecting electrode.

[0134] The photovoltaic device further includes a first electrode and a second electrode, the photoactive region being positioned between the first and second electrodes, the first electrode in contact with the p-type region of the photoactive region, and the second electrode in contact with the n-type region of the photoactive region. The first electrode may include a transparent or light-transmitting conductive material, and the second electrode may include a metal or a second light-transmitting conductive material. The first electrode is a hole collecting electrode, and the second electrode is an electron collecting electrode.

[0135] The photovoltaic device may have a multi-junction structure having a first subcell positioned on a second subcell, the first subcell including a photoactive region containing a perovskite material. The photovoltaic device may have a monolithic integrated structure. In a monolithic integrated multi-junction photovoltaic device, two or more photovoltaic subcells are directly deposited on each other and thus electrically connected in series. The photovoltaic device may further have intermediate regions connecting the first subcell to the second subcell, each intermediate region having one or more interconnection layers.

[0136] A photovoltaic device having a multi-junction structure further includes a first electrode and a second electrode, and the first subcell and the second subcell may be arranged between the first electrode and the second electrode.

[0137] Next, the first electrode may be in contact with the p-type region of the first subcell, and the first electrode comprises a transparent or translucent conductive material. The first electrode is a hole collection electrode, and the second electrode is an electron collection electrode. In a tandem monolithic device, the second electrode is in contact with the second subcell, and the first and second electrodes form an external component at either end of the device. An intermediate layer is placed between the first and second subcells.

[0138] Alternatively, the first electrode may be in contact with the n-type region of the first subcell, and the first electrode comprises a transparent or translucent conductive material. The first electrode is an electron collecting electrode, and the second electrode is a hole collecting electrode. In a tandem monolithic device, the second electrode is in contact with the second subcell, and the first and second electrodes form an external component at either end of the device. An intermediate layer is placed between the first and second subcells.

[0139] If the photovoltaic device has a multi-junction structure, the second subcell of the photovoltaic device may have one of the following: a second perovskite material, crystalline silicon, CdTe, CuZnSnSSe, CuZnSnS, or CuInGaSe(CIGS).

[0140] Alternatively, a multi-junction solar cell may include three subcells. The present invention encompasses perovskite layers having band gaps in the range of 1.1 to 2.5 eV that satisfy each of the subcell requirements in a multi-junction. For example, a top cell having a perovskite layer according to the present invention with a band gap in the range of 2.0 to 2.5 eV, an intermediate subcell having a perovskite layer according to the present invention with a band gap in the range of 1.5 to 2.0 eV, and a bottom subcell including a subcell having an energy band gap in the range of 1.1 to 1.4 eV, are, for example, crystalline silicon or a perovskite layer with a narrow band gap. The band gaps of each subcell may vary relative to each other and depending on the shape of the cell. Generally, the top cell has a wider band gap, the bottom subcell has a lower band gap, and the band gap of the intermediate subcell fits within one of these upper and lower subcell values. Any of the top, intermediate, or bottom subcells may have a perovskite layer according to the present invention.

[0141] The perovskite layer may be prepared as described in International Publication Nos. WO2013 / 171517, WO2014 / 045021, WO2016 / 198889, WO2016 / 005758, WO2017 / 089819, and references “Photovoltaic Solar Energy: From Fundamentals to Applications” (edited by Angele Reinders and Pierre Verlinden, Wiley-Blackwell (2017) ISBN-13:978-1118927465), and “Organo-Inorganic Halide Perovskite Photovoltaic: From Fundamentals to Device Architectures,” Nam-Gyu Park et al., Springer (2016) ISBN-13:978-3319351124).

[0142] In a preferred apparatus of the present invention, the photoactive layer is a compact layer without open porosity.

[0143] The present invention will be explained by the following examples.

[0144] Examples Example 1 Preparation and analysis of mixed halide precursors One method for reducing the number of evaporation sources required for the co-evaporation of multiple precursors involved a combination of mixed metal halide precursors, such as PbI2 and PbBr2. The two materials were mixed in a single crucible and dissolved under high temperatures exceeding 350°C, ambient pressure, and an N2 atmosphere to avoid oxidation. The resulting compound provided a novel mixed halide alloy phase, which can be further sublimated as a single precursor in a single evaporation source as part of a co-evaporation process.

[0145] To confirm the sublimation of the mixed metal halide as a single substance, X-ray photoelectron spectroscopy (XPS) was used to analyze a 200 nm mixed lead halide thin film Pb(I) 1- xBr x Compositional and stoichiometric analyses were performed on the three consecutive film deposition runs. Next, as shown in Figure 1, these compounds were compared with their powder precursor counterparts. The maintenance of the stoichiometry of each component of the molten mixed lead halide across each run indicates that the material behaves as a single precursor during evaporation.

[0146] Example 2 Performance analysis of standard triple-cation bihalide perovskites The performance characteristics of standard triple-cationic bihalide perovskites fabricated using the requested co-evaporation method were also investigated. Planar pin-configured solar cells were first fabricated using ITO electrodes coated with a thin poly(triarylamine) (PTAA) hole transport layer (HTL). Next, 10 Å / s of the precursor FAI, MAI, CsI, and molten mixed halide phases from Example 1 were deposited at deposition rates of 0.6 Å / s, 0.3 Å / s, 0.4 Å / s, and 1.3 Å / s, respectively. -6 Vacuum co-deposition at mbar results in a perovskite light-absorbing layer, FAMACsPb(I 1-x Br x )3 was prepared. The sublimation temperature of the precursor was approximately 155°C for FAI and approximately 125°C for MAI, and Pb(I1-x Br x The temperatures were approximately 310°C for )3 and approximately 485°C for CsI. Subsequently, fullerene ETL and C were deposited by vacuum deposition. 60 This film was capped with a silver upper electrode. While these cells yielded a considerable PCE of over 16%, their thermal stability after stressing in an N2 atmosphere on a hot plate at 85°C was low, resulting in significant degradation of output characteristics, particularly VOCs, after 5 hours (Figures 2A and 2B).

[0147] Similarly, Figure 3B shows the results of X-ray diffraction (XRD) measurements of a triple cation perovskite over continuous thermal stress at different time intervals: "as prepared," 2 days, 7 days, and 9 days. By day 9, a significant increase in the resolved PbI2 peak at approximately 12.7° and a decrease in the intensity of the major perovskite peak at approximately 14.3° were observed. This is a clear indicator of resolution.

[0148] Furthermore, light immersion experiments were also performed on the samples, and they were periodically analyzed by XRD as described above. The films were maintained under constant irradiation at 35°C with an intensity equivalent to one sun. As shown in Figure 3A, a moderate increase in the PbI2 signal was observed after only two days.

[0149] These results highlight the insufficient stability of triple-cation vacuum-deposited triple-cation CsMAFA perovskites under thermal stress, which is a critical requirement for ensuring the lifetime of PV devices.

[0150] Example 3 Performance analysis of large cationic additive multicomponent perovskites As described in Example 2, standard triple-cationic double-halide perovskites do not exhibit acceptable thermal stability. In the present invention, a large cationic additive, namely GA, is introduced at the A site of the structure, and its effect on stability is determined.

[0151] Quadrivalent cation FAGAMACsPb(I 1-x Br x) To form (0000895), FAI and GAI were mixed in a ratio of 10:1 in the same evaporation source, and for each chamber, using the same deposition rate and temperature as shown in Example 2, CsI, MAI, and Pb(I 1-x Br x )3 were co-evaporated with separate source sources to form a perovskite film.

[0152] Similarly, by combining FAI and GAI from one source source as described above, CsI from another source source, and a mixed halide composition from a third source source, and co-evaporating all three source sources, the triple-cation FAGACsPb(I 1-x Br x )3 was also synthesized.

[0153] Also, using four separate source sources of FAI, MAI, CsI, and Pb(I 1-x Br x )3, according to Example 2, a reference triple-cation formulation without a large cation additive, namely FAMACsPb(I 1-x Br x )3 was synthesized.

[0154] Then, all films were subjected to thermal stress at 85 °C in N2 and monitored over a week. As shown in Figure 4, using X-ray diffraction (XRD), any structural changes such as the formation of a decomposition phase (PbI2 peak) were identified.

[0155] The presence of GA in both triple- and quadruple-cations significantly enhanced the thermal stability compared to compounds without reference GA. There were no attenuation peaks in the "as-prepared" films, and the degradation peaks after one week of heat treatment were significantly smaller. Some small amounts of delta phases were also present, but these were not necessarily harmful to the material. As shown in Pavlovetc et al., "Suppression of Cation Migration in Triple-Cation Lead Halide Perovskites", ACS Energy Lett. 2020, 5, 2802, these are described as maintaining the stability of the perovskite.

[0156] Furthermore, Figure 5B shows ex-situ XRD patterns for the quadruple cation perovskite analyzed at various stages over the entire 37-day period. While there is no discernible growth of the degradation signal and the crystallinity of the major peaks is maintained at each stage, in the case of the triple cation without "large" additives, degradation is accelerated even within a week, as seen in Figure 3B.

[0157] In addition, photoimmersion of the quadruple cation was performed in parallel with the XRD measurement. This maintained structural integrity, and as shown in Figure 5A, no significant degradation PbI2 products were observed.

[0158] To further evaluate the combined power and stability device characteristics of multi-component perovskites incorporating GA, a quadruple cation FAGAMACsPb(I) was used. 1-x Br x The PCE of )3 was evaluated under high-temperature stress in an N2 atmosphere at 85°C for one month. Throughout the period of continuous thermal stress, the cells were found to maintain 80% of their initial efficiency (Figure 6), demonstrating the excellent performance characteristics of the vacuum-deposited GA-containing film.

[0159] The present invention includes the following embodiments. 1. A method for forming a perovskite material from multiple evaporation sources, (i) A first evaporation source comprising a mixture of cosublimable organic halides, The aforementioned organic halogenated material is a. A first organic halogen containing organic cation A, b. A second organic halide comprising an organic cation A' different from that of A, and having a larger ionic radius than the first organic cation A. A first evaporation source having, (ii) A second evaporation source comprising one or more metal halides having the following formula (I): B(X y X' 1-y )2(I) Here, B is a divalent metal cation, X and X' are different halides, and 0 ≦ y < 1. A second evaporation source, (iii) one or more different organic halides from one or more other evaporation sources, and / or (iv) one or more inorganic halides from one or more other evaporation sources, co-sublime to form a perovskite material, wherein the perovskite material contains three or more different cations in addition to the B cation. The method. 2. The method according to aspect 1, wherein the perovskite material contains a mixed halide, and thus 0 < y < 1. 3. The method according to aspect 1 or 2, wherein the perovskite material contains three or more different monovalent cations. 4. The method according to any one of aspects 1 to 3, comprising three or four evaporation sources. 5. The method according to any one of aspects 1 to 4, wherein the first and second organic halides contain the same halide. 6. The method according to any one of aspects 1 to 5, wherein the second organic halide in step (i) contains a monovalent cation A'. 7. The method according to any one of aspects 1 to 6, wherein the one or more organic halides in step (iii) and / or the one or more inorganic halides in step (iv) contain a monovalent cation. 8. The method according to any one of aspects 1 to 7, wherein the first organic halide contains an organic cation A which is a monovalent organic cation, preferably FA. 9. The method according to any one of aspects 1 to 8, wherein the second organic halide contains an organic monocation A' having an ionic radius larger than that of the first organic cation A, preferably selected from guanidinium (GA), dimethylammonium (DMA), benzylammonium (BzA), ethylammonium (EA), imidazolium (Im), acetamidinium (Ac) and phenylethylammonium (PEA), and preferably A' is GA. 10. The method according to any one of aspects 1 to 9, including a step of mixing two cationic halide salts by a mechanical mixing method before the step (i) of preparing the first evaporation source. 11. Step (ii) has a preceding step of forming a compound of general formula (I) B(X y X’ 1-y )2, The step has a step of mixing one or more metal halides, BX2 and / or BX’2, and a step of heating in an inert atmosphere, and the method according to any one of aspects 1 to 10. 12. B(X y X’ 1-y )2 is PbI y Br 1-y , and the step has a step of mixing PbBr2 and PbI2 and heating in an inert atmosphere, and the method according to aspect 11. 13. The one or more metal halides BX2 and BX’2 include two different B cations and two different halide anions, The general formula (I) is B x B’ 1-x (X y X’ 1-y )2, where 0 < x < 1 and 0 < y < 1, B is a divalent metal cation different from B’, and preferably B and B’ are selected from Pb and Sn, and the method according to aspect 10. 14. In step (ii), the second evaporation source is as follows: a) PbI2 and SnI2 from which a single precursor phase Pb x Sn 1-x I2 is obtained; b) PbBr2 and SnBr2 from which a single precursor phase Pb x Sn 1-x Br2 is obtained; c) PbI2 and SnBr2 from which a single precursor phase Pb x Sn 1-x (I 1-y Br y )2 is obtained; and d) Pb x Sn 1-x(I 1-y Br y )2 is obtained, PbBr2 and SnI2; The method according to aspect 11, having two mixed metal halides selected from , where 0 < x < 1 and 0 < y < 1. 15. Having step (iv) of providing an inorganic halide, Preferably, the inorganic halide is CsI or CsBr, the method according to any one of aspects 1 to 14. 16. Comprising four evaporation sources, In step (ii), y > 0 and two different metal halides are mixed, In step (iii), an organic halide is provided to a third evaporation source, In step (iv), an inorganic halide is provided to a fourth evaporation source, the method according to aspect 15. 17. In step (ii), the two metal halides to be mixed are PbI2 and PbBr2, and a single precursor phase Pb(I y Br 1-y )2 is obtained, where 0 < y < 1, the method according to aspect 16. 18. When not dependent on aspect 2, comprising four evaporation sources, In step (ii), y = 0 and only one halide component is provided in the perovskite material, In step (iii), an organic halide is provided to a third evaporation source, In step (iv), an inorganic halide is provided, preferably the inorganic halide is CsI or CsBr, the method according to aspects 1 and 3 to 11. 19. When not dependent on aspect 2, comprising four evaporation sources, In step (ii), y = 0 and in step (ii), only one halide component is provided, In step (iii), an organic halide is provided to a third evaporation source, (iv) The preparatory step of preparing involves heating the two inorganic halides, preferably CsI and CsBr, together in a single evaporation source under an inert atmosphere, and Cs(I z Br 1-z ), where 0 < z < 1, to obtain a precursor of a mixed halide phase, the method according to embodiments 1, and 3 to 11. 20. The method according to embodiments 1 to 19, wherein in step (iii), CsI is provided to a third evaporation source and MAI is provided to a fourth evaporation source. 21. The method according to embodiments 1 to 20 for forming a thin film of a perovskite material. 22. The method according to embodiments 1 to 21, wherein the perovskite material has a band gap of 1.1 to 2.5 eV. 23. The perovskite material has the general formula (II), A a A’ b A’’ c A’’’ d B x B’ 1-x (X y X’ 1-y )3(II) where, When both A and A’ are present as halides, A is a first monovalent organic cation capable of co-sublimation with A’, A’ is a second monovalent organic cation having an ionic radius larger than A, A’’ and A’’’ are independently selected from monovalent inorganic cations or another monovalent organic cation, All A cations are different from each other and at least three kinds are present, 0 < a < 1, 0 < b < 1, 0 < c < 1, 0 ≤ d < 1, a + b + c + d = 1, 0 ≤ x < 1 and 0 ≤ y < 1, and B and B’ are independently selected from divalent metal cations, The method according to any one of Aspects 1 to 22, wherein X and X’ are independently selected from halide anions. 24. A’ and A’’’ are different from each other. (iii) A group of organic cations containing MA or FA, preferably MA; and / or (iv) Cs or Rb cations, preferably Cs The method according to Aspect 23, selected from the above. 25. X and X’ are different from each other, selected from Cl, Br, and I. Preferably, the halide X and X’ are I and Br. The method according to Aspect 23 or 24. 26. B is Pb 2+ or Sn 2+ And optionally, B’ is different from B and is selected from Pb 2+ or Sn 2+ The method according to any one of Aspects 23 to 25. 27. A perovskite material obtained by the method according to any one of Aspects 1 to 26. 28. A perovskite material comprising a quadruple cation double halide and, optionally, a mixed metal, FA a GA b MA c Cs d Pb(I y Br 1-y )3, FA a EA b MA c Cs c Pb(I y Br 1-y )3, FA a BzA b MA c Cs d Pb(I y Br 1-y )3, FA (iii) A group of organic cations containing MA or FA, preferably MA; and / or The method according to Aspect 23, selected from the above. 25. X and X’ are different from each other, selected from Cl, Br, and I. Preferably, the halide X and X’ are I and Br. The method according to Aspect 23 or 24. 26. B is Pb 2+ or Sn 2+ And optionally, B’ is different from B and is selected from Pb 2+ or Sn 2+ The method according to any one of Aspects 23 to 25. 27. A perovskite material obtained by the method according to any one of Aspects 1 to 26. 28. A perovskite material comprising a quadruple cation double halide and, optionally, a mixed metal, FA a GA b MA c Cs d Pb(I y Br 1-y )3, FA a EA b MA c Cs c Pb(I y Br 1-y )3, FA a BzA b MA c Cs d Pb(I y Br 1-y )3, FA a DMA b MA c Cs d Pb(I y Br 1-y )3, FA a GA b MA c Csd Sn(I y Br 1-y )3、FA a EA b MA c Cs c Sn(I y Br 1-y )3、FA a BzA b MA c Cs d Sn(I y Br 1-y )3、FA a DMA b MA c Cs d Sn(I y Br 1-y )3、FA a Im b MA c Cs d Pb(I y Br 1-y )3、FA a Im b MA c Cs d Sn(I y Br 1-y )3、FA a PEA b MA c Cs d Sn(I y Br 1-y )3、FA a Ac b MA c Cs d Pb(I y Br 1-y )3、FA a Ac b MA c Cs d Sn(I y Br 1-y )3、FA a GA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3、FA a BzA b MA c Cs d Pbx Sn 1-x (I y Br 1-y )3, FA a EA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a DMA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a Im b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a PEA b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3, FA a Ac b MA c Cs d Pb x Sn 1-x (I y Br 1-y )3 selected from, where 0 < a < 1, 0 < b < 1, 0 < c < 1, 0 < d < 1, a + b + c + d = 1, 0 < x < 1, 0 < y < 1, perovskite material. 29. A perovskite material comprising a triple cation double halide and, optionally, a mixed metal, MA a GA b Cs c Pb(I y Br 1-y )3, FA a BzA b MA c Pb(I y Br 1-y )3, FA a BzAb Cs c Pb(I y Br 1-y )3、MA a BzA b Cs c Pb(I y Br 1-y )3、MA a DMA b Cs c Pb(I y Br 1-y )、FA a GA b MA c Sn(I y Br 1-y )3、FA a GA b Cs c Sn(I y Br 1-y )3、MA a GA b Cs c Sn(I y Br 1-y )3、FA a BzA b MA c Sn(I y Br 1-y )3、FA a BzA b Cs c Sn(I y Br 1-y )3、MA a BzA b Cs c Sn(I y Br 1-y )3、FA a DMA b Cs c Sn(I y Br 1-y )3、FA a DMA b MA c Sn(I y Br 1-y )3、MA a DMA b Cs c Sn(I y Br 1-y )、FA a Im b Cs c Sn(Iy Br 1-y )3、FA a TO BE b Cs c Pb(I) y Br 1-y )3、FA a TO BE b Cs c Sn(I) y Br 1-y )3、FA a Ac b Cs c Sn(I) y Br 1-y )3、FA a BzA b AND c Pb(I) y Br 1-y )3、FA a BzA b AND c Sn(I) y Br 1-y )3、FA a I am b AND c Pb(I) y Br 1-y )3、FA a I am b AND c Sn(I) y Br 1-y )3、FA a TO BE b AND c Pb(I) y Br 1-y )3、FA a TO BE b AND c Sn(I) y Br 1-y )3、FA a EA b Cs c Sn(I) y Br 1-y )3、FA a EA b AND c Sn(I) y Br 1-y )3、MA a EA b Cs c Pb(I) y Br 1-y )3、MAa EA b Cs c Sn(I y Br 1-y )3、FA a GA b MA c Pb x Sn 1-x (I y Br 1-y )3、FA a GA b Cs c Pb x Sn 1-x (I y Br 1-y )3、MA a GA b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a BzA b MA c Pb x Sn 1-x (I y Br 1-y )3、FA a BzA b Cs c Pb x Sn 1-x (I y Br 1-y )3、MA a BzA b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a DMA b Cs c Pb x Sn 1-x (I y Br 1-y )3、FA a DMA b MA c Pb x Sn 1-x (I y Br 1-y )3、MA a DMA b Cs c Pbx Sn 1-x (I y Br 1-y )3, FA a Im b MA c Pb x Sn 1-x (I y Br 1-y )3, FA a Im b Cs c Pb x Sn 1-x (I y Br 1-y )3, FA a PEA b MA c Pb x Sn 1-x (I y Br 1-y )3, FA a PEA b Cs c Pb x Sn 1-x (I y Br 1-y )3, FA a Ac b MA c Pb x Sn 1-x (I y Br 1-y )3, FA a Ac b Cs c Pb x Sn 1-x (I y Br 1-y ) Selected from 3, where 0 <a<1、0<b<1、0<c<1、0<d<1、a+b+c+d=1、0<x<1、0<y<1である、ペロブスカイト材料。30. A semiconductor device having a photoactive region comprising a perovskite material according to any one of embodiments 27 to 29. 31. The semiconductor device according to embodiment 30, wherein the semiconductor device is an optoelectronic device, preferably a photovoltaic device having a photoactive region. 32. A photovoltaic device comprising a photovoltaic material prepared according to the method described in any one of the embodiments 1 to 26, It has a photoactive region containing a thin film of perovskite material, A photovoltaic device in which the thickness of the perovskite material thin film is in the range of 50 nm to 2000 nm. 33. The photovoltaic device according to embodiment 32, wherein the photoactive region comprises an n-type region including at least one n-type layer and a layer of the perovskite material in contact with the n-type region. 34. The photoactive region is An n-type region containing at least one n-type layer, A p-type region containing at least one p-type layer, A layer of perovskite material disposed between the n-type region and the p-type region, A photovoltaic device according to embodiment 32 or 33, having the following characteristics. 35. A multi-junction photovoltaic device having 2 or more subcells, The first subcell has a photovoltaic device according to any one of embodiments 32 to 34, A multijunction photovoltaic device comprising another subcell having a photoactive layer, the photoactive layer optionally having a perovskite layer prepared according to any one of embodiments 1 to 26.

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