An apparatus for perovskite fabrication

Abstract

An apparatus for perovskite fabrication, the apparatus comprising: a chemical vapour deposition (CVD) processing chamber configured to communicate with a first vapour source and a passivation vapour source, wherein the CVD processing chamber is configured to receive: (i) a substrate; (ii) first vapour from the first vapour source; and (iii) passivation vapour from the passivation vapour source; and a heatable substrate holder disposed in the processing chamber, the heatable substrate holder configured to: (i) support the substrate; and (ii) heat the substrate to facilitate perovskite crystal growth on the substrate.

Description

An apparatus for perovskite fabricationTechnical Field

[0001] The present disclosure generally relates to an apparatus for perovskite fabrication, and methods of using said apparatus to manufacture perovskite.Background

[0002] Photovoltaic (PV) cells, also known as solar cells, comprise a semiconducting material which enables the solar cell to absorb light and convert it to electricity. Silicon is one of the most widely used semiconducting materials for solar cells. Silicon-based single p-n junction solar cells are approaching their theoretical maximum efficiency of around 30% (the Shockley-Queisser limit).

[0003] Perovskite-based and Perovskite / Si tandem solar cells suggest comparable or better efficiency limits compared to silicon-based solar cells, and (in theory) reduced mass-manufacturing costs. One challenge to commercialisation is the difficulty in the large-scale fabrication of high-quality perovskite

[0004] Some larger-scale perovskite fabrications use an evaporation technique, wherein a source material is evaporated and condensed on a substrate. However, although evaporation and condensation are mature deposition techniques in industry, they are not well suited for perovskite fabrication. Evaporating perovskite source materials to form perovskite is a challenge because of the difficulty in precisely controlling the perovskite composition. This is due to the deposition ratio of these source materials being unstable due to their material properties.

[0005] High efficiency perovskite solar cells have been fabricated through lab-scale solution-based techniques. However, difficulties in upscaling from the controlled, smaller lab environment means mass production is not feasible or is a significant challenge. For example, the absolute efficiency of the perovskite solar cell may decrease by about 0.8% with each order of magnitude increase in device area, when using existing solution-based fabrication techniques. Moreover, the solution-based methods may not provide uniform high quality perovskite on a textured Si surface which may be critical for the fabrication of perovskite / Si tandem solar cells.

[0006] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

[0007] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.Summary

[0008] Some embodiments relate to an apparatus for perovskite fabrication, the apparatus comprising:a chemical vapour deposition (CVD) processing chamber configured to communicate with a first vapour source and a passivation vapour source, wherein the CVD processing chamber may be configured to receive: (i) a substrate; (ii) first vapour from the first vapour source; and (iii) passivation vapour from the passivation vapour source; anda heatable substrate holder disposed in the processing chamber, the heatable substrate holder may be configured to: (i) support the substrate; and (ii) heat the substrate to facilitate perovskite crystal growth on the substrate.

[0009] The apparatus may further comprise a humidity chamber configured to communicate with a humidity source, wherein the humidity chamber may be configured to receive the substrate from the CVD processing chamber, and wherein the humidity chamber may be configured to receive humidity from the humidity source.

[0010] The apparatus may further comprise a first transfer system comprising a first passage connecting the CVD processing chamber and the humidity chamber, wherein the first transfer system may be configured to transfer the substrate through the first passage from the CVD processing chamber to the humidity chamber.

[0011] The apparatus may further comprise a solvent chamber configured to communicate with a solvent source. The solvent chamber may be configured to receive the substrate from the CVD processing chamber, and wherein the solvent chamber may be configured to receive solvent from the solvent source. The apparatus may further comprise a second transfer system comprising a second passage connecting the CVD processing chamber and the solvent chamber, wherein the second transfer system may be configured to transfer the substrate through the second passage from the CVD processing chamber to the solvent chamber.

[0012] The apparatus may further comprise a solvent chamber configured to communicate with a solvent source and wherein the solvent chamber may beconfigured to receive the substrate from the humidity chamber, and wherein the solvent chamber may be configured to receive solvent from the solvent source.

[0013] The apparatus may further comprise a third transfer system comprising a third passage connecting the humidity chamber and the solvent chamber, wherein:(i) the first transfer system may be configured to transfer the substrate through the first passage from the CVD processing chamber to the humidity chamber; and (ii) the third transfer system may be configured to transfer the substrate through the third passage from the humidity chamber to the solvent chamber.

[0014] The CVD processing chamber may be configured to communicate with a second vapour source containing a second vapour, wherein the CVD processing chamber may be configured to sequentially expose the substrate to the first vapour and the second vapour.

[0015] The apparatus may further comprise a vacuum system connected to at least one of the CVD processing chamber, the humidity chamber, and / or the solvent chamber to remove vapour.

[0016] The CVD processing chamber may comprise a CVD processing chamber heater for adjusting a temperature of the CVD processing chamber.

[0017] The humidity chamber may comprise a humidity chamber heater for adjusting a temperature of the humidity chamber.

[0018] The CVD processing chamber may comprise a first outlet device for dispensing the first vapour into the CVD processing chamber, the first outlet device being fluidly connected to the first vapour source. A distance between the heatable substrate holder and the first outlet device may be variable.

[0019] The solvent chamber may comprise a second outlet device for dispensing the solvent into the solvent chamber, the second outlet device being fluidly connected to the solvent source. The solvent chamber may further comprise a substrate holder for holding the substrate, wherein a distance between the substrate holder and the second outlet device may be variable.

[0020] The apparatus may further comprise a carrier gas system in fluid communication with the first vapour source and the second vapour source, wherein the carrier gas system may be directly in fluid communication with the CVD processing chamber.

[0021] The apparatus may further comprise a set of valves for controlling a flow of the first vapour through the CVD processing chamber. The apparatus may further comprise a controller and a plurality of gas sensors, wherein operation of any one valve in the set of valves may be controlled by the controller based on measurements from at least one of the plurality of gas sensors.

[0022] Some embodiments relate to a method of perovskite fabrication, the method comprising:subjecting a substrate comprising a perovskite precursor film to a pretreatment operation;after the pre-treatment operation, subjecting the substrate to a processing operation;after the processing operation, subjecting the substrate to a humidifying operation;after the humidifying operation, subjecting the substrate to a finishing operation; andafter the finishing operation, subjecting the substrate to a post-processing operation;wherein the pre-treatment operation comprises:exposing the substrate to a first vapour comprising a first perovskite precursor;causing the first vapour and the perovskite precursor film to undergo a first chemical reaction resulting in an intermediate perovskite phase being formed on the substrate;wherein the processing operation comprises:exposing the substrate to a second vapour comprising a second perovskite precursor;causing the second vapour and the intermediate perovskite phase to undergo a second chemical reaction resulting in a final perovskite phase being formed on the substrate, the final perovskite phase comprising a plurality of perovskite grains;wherein the humidifying operation comprises applying heat and humidity to the substrate to increase the size of the plurality of perovskite grains;wherein the finishing operation comprises applying a solvent to the substrate to smoothen a boundary between adjoining perovskite grains; andwherein the post-processing operation comprises exposing the substrate to a passivation vapour to passivate the substrate.

[0023] Causing the first vapour and the perovskite precursor film to undergo a first chemical reaction may comprise heating the substrate and / or the first vapour.

[0024] Causing the second vapour and the intermediate perovskite phase to undergo a second chemical reaction may comprise heating the substrate and / or the second vapour.

[0025] The method may be performed: (i) at atmospheric pressure; or (ii) at less than atmospheric pressure.

[0026] Some embodiments relate to a method of perovskite fabrication, the method comprising use of the apparatus as described above.Brief Description of Drawings

[0027] Embodiments are described in further detail below, by way of example, with reference to the accompanying drawings, in which:

[0028] Fig. 1 is a schematic of an apparatus for perovskite fabrication, according to some embodiments;

[0029] Fig. 2 is a schematic of an apparatus for perovskite fabrication, according to some embodiments;

[0030] Fig. 3 is a schematic of an apparatus for perovskite fabrication, according to some embodiments; and

[0031] Fig. 4 is a flowchart of a method for perovskite fabrication, according to some embodiments,Detailed Description

[0032] The present disclosure generally relates to an apparatus for perovskite fabrication, and methods of using said apparatus to manufacture perovskite.

[0033] Specifically, some embodiments of the present disclosure relate to an apparatus for chemical vapour deposition of a perovskite material with good uniformity for conformal coating on flat or rough substrates.

[0034] The apparatus may generate organic vapours for reacting with at least one inorganic precursor or framework to form perovskite materials on a substrate.

[0035] Some embodiments of the present disclosure provide a chemical vapour deposition (CVD) apparatus capable of large-scale and conformal deposition on a substrate to manufacture perovskite and perovskite / Si solar cells. Some embodiments of the present disclosure are configured to form perovskite on a substrate having a rough silicon (Si) surface. Some embodiments of the present disclosure are configured to enable large-scale, uniform formation of perovskite on a substrate, which may improve the manufacturing scale and efficiency of perovskite and perovskite / Si solar cells and accelerate commercialisation.

[0036] Some embodiments of the present disclosure provide an apparatus for use with a hybrid vapour deposition method combining physical vapour deposition (PVD) and CVD. The apparatus may receive a PVD-treated precursor film sample / substrate and subject it to CVD in a processing chamber. In some embodiments, the apparatus comprises at least two chambers. The at least two chambers may comprise a processing chamber and a humidity chamber. The at least two chambers may comprise a processing chamber and a solvent chamber. In some embodiments, the apparatus comprises at least three chambers. The at least three chambers may comprise a processing chamber, a humidity chamber, and a solvent chamber.

[0037] The different chambers may enable precise control of the perovskite formation process. Each chamber may expose the sample to different conditions, which affects the growth of perovskite crystals / grains on the substrate. The use of the apparatus may result in a perovskite film forming on the substrate with good uniformity, particularly over larger areas (-100 cm2).

[0038] In some embodiments, the apparatus is configured to enable perovskite crystals / grains coarsening. The perovskite crystals / grains may be enlarged after exposure to at least one of the humidity chamber or the solvent chamber, as will be subsequently discussed herein.

[0039] In some embodiments, the apparatus is configured to enable a passivation process. In the passivation process, the substrate may be passivated after exposure to at least one of the humidity chamber and the solvent chamber. For example, the substrate may be returned to the processing chamber, where the passivation process may occur. The passivation process may be configured to coat the substrate (and the perovskite formed thereon) with a protective film. The protective film may be configured to reduce the likelihood of oxidation or corrosion on the substrate. The protective film (which may also be referred to as a passivator) may be configured to improve the optical -electrical properties and stability of the perovskite formed on the substrate. Theprotective film may comprise a layer of 2D perovskite crystals / grains that coat 3D perovskite crystals / grains formed on the substrate. The 2D perovskite crystals / grains may address any cation / anion vacancies defects between the 3D perovskite crystals / grains that result during their formation. By addressing any cation / anion vacancies defects, an integral perovskite crystal / grain may be formed, thereby improving the overall quality of the perovskite film.

[0040] Some embodiments of the present disclosure enable manufacture of perovskite films with improved uniformity compared to traditional physical vapour deposition (PVD) and chemical vapour deposition (CVD) methods. Some embodiments of the present disclosure are suitable for mass-production. The manufacturing scale and efficiencies offered by mass-production may make one or more embodiments of the present disclosure suitable for reducing the cost of manufacturing perovskite solar cells.

[0041] Figs. 1-3 show apparatus 100, 200, 300 for perovskite fabrication according to three different embodiments of the present disclosure. The apparatus 100, 200, 300 of each of Figs. 1-3 comprises a chemical vapour deposition (CVD) processing chamber 110, 210, 310.

[0042] The CVD processing chamber 110, 210, 310 may be configured to receive a substrate 102, 202, 302, respectively. The substrate 102, 202, 302 may be a sheet of material, such as glass. Indium tin oxide (ITO) glass may be used as a substrate for example. Prior to entering the CVD processing chamber 110, 210, 310, the substrate 102, 202, 302 may be subjected to a physical vapour deposition (PVD) process, wherein a perovskite precursor is deposited on the substrate 102, 202, 302 to form a perovskite precursor film. The perovskite precursor may be a metal halide such as lead iodide (Pbh), for example.

[0043] The apparatus 100, 200, 300 may further comprise a substrate holder 120, 220, 320 disposed in the processing chamber 110, 210, 310. The substrate holder 120, 220, 320 is configured to support the substrate 102, 202, 302 in the respective processing chambers 110, 210, 310.

[0044] The processing chamber 110, 210, 310 may be configured to communicate via a conduit system 103, 203, 303 with respective first vapour sources 104, 204, 304 and receive first vapour from the first vapour source 104, 204, 304. The apparatus 100, 200, 300 may comprise a first pump connected to the first vapour source 104, 204, 304. The first pump may be configured to pump the first vapour from the first vapour source 104, 204, 304 into the processing chamber 110, 210, 310. The conduit system 103,203, 303 may comprise a gas output 103 A, 203 A, 303 A which is configured to allow release of excess vapour from the conduit system 103, 203, 303.

[0045] The processing chamber 110, 210, 310 may respectively comprise a first outlet device 112, 212, 312 for dispensing the first vapour into the processing chamber 110, 210, 310. The first outlet device 112, 212, 312 may be fluidly connected to the first vapour source 104, 204, 304. The first outlet device 112, 212, 312 may be a showerhead-like structure, comprising a spaced apart plurality of nozzles, configured to disperse the first vapour through the processing chamber 110, 210, 310. The first outlet device 112, 212, 312 may be disposed directly above the substrate so that the gravity assists the vapour deposition process. In contrast to a “horizontal” deposition process (where gravity generally does not assist the vapour deposition process), such a “vertical” deposition process can result in a more uniform thickness of vapour deposition, and therefore a more uniform thickness of perovskite layer formation on the substrate.

[0046] A distance between the substrate holder 120, 220, 320 and the first outlet device 112, 212, 312 may be varied, e.g. manually or automatically. Varying the distance between the substrate holder 120, 220, 320 and the first outlet device 112, 212, 312 may allow control of the intensity and / or spread of the first vapour on the substrate 102, 202, 302, and therefore control of the formation of the perovskite crystals / grains.

[0047] In some embodiments, the substrate holder 120, 220, 320 is connected to the floor of the processing chamber 110, 210, 310. The floor of the processing chamber 110, 210, 310 may be raised to bring the substrate holder 120, 220, 320 closer to the first vapour source 104, 204, 304, thereby reducing the volume of the processing chamber 110, 210, 310. Changing the volume of the processing chamber 110, 210, 310 enables control of the vapour diffusion through the processing chamber 110, 210, 310. For example, vapour will diffuse more quickly through a smaller volume than a larger volume. The chemical reaction rate can be controlled by controlling the diffusion of the vapour through the processing chamber 110, 210, 310.

[0048] The first vapour may comprise a first perovskite precursor such as an organic halide (organohalide). The first vapour may comprise Formamidinium iodide (FAI), Methylammonium chloride (MAC1), or Methylammonium bromide (MABr), for example. The first vapour may be configured to react with the Pbh perovskite precursor on the substrate 102, 202, 302 and form perovskite. For example, when FAI is used, a formamidinium lead iodide perovskite may be formed. The associated chemical reaction is:Pbl2+ FAI = FAPbI3

[0049] By combining a PVD process and a CVD process, a perovskite layer may be formed on the substrate 102, 202, 302 that exhibits improvements over perovskites formed by CVD or PVD alone. For example, in a PVD process, it may be difficult to control or stabilise the deposition ratio of the organic halide vapour. For example, in a CVD process, high temperatures may be required for effective deposition of the inorganic halide. In some embodiments of the present disclosure, a combined PVD and CVD process may be used to produce formamidinium lead iodide (FAPbL) perovskites. Such formamidinium lead iodide perovskites may exhibit higher thermal stability and a band gap of 1.48 eV. The apparatus 100, 200, 300 may provide flexibility to control the parameters which affect the perovskite formation process through the use of different chambers and / or different perovskite precursor source tanks, as described herein.

[0050] The perovskite layer formed by exposing the substrate 102, 202, 302 to the first vapour may be referred to as an intermediate perovskite phase. A subsequent or final perovskite phase may be formed on the substrate 102, 202, 302 by exposing the intermediate perovskite phase to a second vapour. An operation forming the intermediate perovskite phase may be referred to as a pre-treatment operation. An operation forming the subsequent (or final) perovskite phase may be referred to as a processing operation.

[0051] In some embodiments, the processing chamber 110, 210, 310 is configured to communicate with a second vapour source 105, 205, 305 and receive second vapour from the second vapour source 105, 205, 305. The apparatus 100, 200, 300 may comprise a second pump connected to the second vapour source 105, 205, 305. The second pump may be configured to pump the second vapour from the second vapour source 105, 205, 305 into the processing chamber 110, 210, 310.

[0052] The second vapour may comprise a second perovskite precursor such as an organic halide. The second vapour may comprise Formamidinium iodide (FAI), Methylammonium chloride (MAC1), or Methylammonium bromide (MABr), for example. The second vapour may be configured to react with the intermediate perovskite phase on the substrate 102, 202, 302 and form the subsequent or final perovskite phase.

[0053] The processing chamber 110, 210, 310 may be configured to sequentially expose the substrate 102, 202, 302 to the first vapour and the second vapour. The apparatus 100, 200, 300 may further comprise a set of valves for controlling a flow ofthe first vapour through the processing chamber 110, 210, 310. The set of valves may further control a flow of the second vapour through the processing chamber 110, 210, 310. To sequentially expose the substrate 102, 202, 302 to the first vapour and the second vapour, the set of valves may be comprise at least a first valve and a second valve. The first valve may be opened to release a required amount of first vapour into the processing chamber 110, 210, 310. The first valve may be closed, and then the second valve opened to release a required amount of second vapour into the processing chamber 110, 210, 310.

[0054] The apparatus 100, 200, 300 may further comprise a controller and a plurality of gas sensors. Operation of any one valve in the set of valves may be controlled by the controller based on measurements from at least one of the plurality of gas sensors, for example. The controller and the set of valves may be part of a mass flow controller (MFC) 106, 206, 306. Each one of the first vapour sources 104, 204, 304 and the second vapour sources 105, 205, 305 may have individual MFCs 106, 206, 306 which independently control the flow of vapour. The set of valves may be automatically operated, based on predetermined settings. Additionally or alternatively, the set of valves may be manually operated, based on user input. In some embodiments, the automatic operation of the set of valves may be overridden by the user in a manual mode of operation.

[0055] During the deposition process, the pressure in the chambers may be in the range of 0.1 mbar to 1013 mbar. The pressure in the processing chamber during the deposition process may significantly influence formation of the perovskite layer. For example, the pressure in the processing chamber may affect the crystallinity and defect properties of the perovskite layer. The pressure in the processing chamber may manipulate the reaction rate of the perovskite precursor film (e.g. a metal halide) and the organic halide vapour. The perovskite precursor film may fully react (full crystal formation and development) with the organic halide vapour when the pressure in the processing chamber reaches a certain level. Accordingly, once this pressure is reached, the crystal quality of the perovskite layer is improved. The thickness of the perovskite layer formed on the substrate is dependent on the amount of precursor vapour deposited on the substrate.

[0056] The processing chamber 110, 210, 310 may be configured to communicate with a passivation vapour source 107, 207, 307 and receive passivation vapour from the passivation vapour source 107, 207, 307. The passivation process may provide a protective layer for the perovskite formed on the substrate 102, 202, 302. The passivation process may be referred to as a post-processing operation.

[0057] The passivation process may fix defects in the perovskite crystal / grain structure formed during the PVD process and / or the CVD process. The passivation vapour may comprise phenethylammonium iodide (PEAI) although one or more other passivation vapours that may be used include:• 4-tert-butyl-benzylammonium iodide (tBBAI)• ethylammonium iodide (EAI)• Imidazolium iodide (IAI)• guanidinium iodide (GUAI)• n-hexyl trimethyl ammonium bromide (HTAB)• naphthylmethylamine iodide (NMAI)• 1 -naphthylmethylammonium bromide (NMaBr)• n-butylammonium bromide (C4Br)• n-hexylammonium bromide (C6Br)• n-octylammonium bromide (C8Br)• (IH-pyrazole-l-yr)pyridine (PZPY)• polyamide imide (PAI)

[0058] The first vapour source 104, 204, 304 may comprise a first container configured to contain the first vapour. The second vapour source 105, 205, 305 may comprise a second container configured to contain the second vapour. The first vapour and the second vapour may comprise different perovskite precursors to each other. However, in some embodiments, the first vapour and the second vapour comprise the same perovskite precursors. In some embodiments, the first vapour and the second vapour comprise the same perovskite precursors, but in different quantities.

[0059] The sublimation temperatures of the perovskite precursors of the first and second vapours may be similar, and may typically be below 200 degrees Celsius, for example. The perovskite precursors of the first and second vapours may be volatile and sublimate due to temperature or pressure changes induced in the first and / or second vapour sources.

[0060] The apparatus 100, 200, 300 may further comprise a carrier gas system 108, 208, 308 in fluid communication with the first vapour source 104, 204, 304 and the second vapour source 105, 205, 305. The carrier gas system 108, 208, 308 may be in fluid communication with the passivation vapour source 107, 207, 307. The carrier gassystem 108, 208, 308 may be directly in fluid communication with the processing chamber 110, 210, 310. The carrier gas system 108, 208, 308 may dispense a carrier gas (e.g., an inert gas such as nitrogen or argon) which may help disperse the first and / or second vapours through the processing chamber 110, 210, 310. The carrier gas may help to control the flow rate of the first and / or second vapours. The carrier gas system 108, 208, 308 may also be used in a purging operation to clear the processing chamber 110, 210, 310 of any leftover gas.

[0061] The apparatus 100, 200, 300 may further comprise a vacuum system 109, 209, 309 connected to at least one of the processing chamber 110, 210, 310 to remove vapour. The vacuum system 109, 209, 309 may configured to evacuate the chamber 110, 210, 310 of dust and other particulates (purging operation). The vacuum system 109, 209, 309 may be configured to reduce the pressure in the chamber to less than atmospheric pressure. The vacuum system 109, 209, 309 may be configured to facilitate the chemical deposition of the vapour on the substrate 102, 202, 302. The vacuum system 109, 209, 309 may work in cooperation with the carrier gas system 108, 208, 308. The purging operation may comprise using the purging / vacuum system 109, 209, 309.

[0062] In the embodiments of Figs. 1 to 3, the processing chamber 110, 210, 310 is defined by at least one wall, a floor, and a ceiling. The at least one wall, floor, and ceiling may be connected to define the interior volume of the processing chamber 110, 210, 310.

[0063] The processing chamber 110, 210, 310 may comprise a processing chamber heater for adjusting a temperature of the processing chamber 110, 210, 310. In some embodiments, the at least one wall of the processing chamber 110, 210, 310 is heatable. The at least one of the walls of the processing chamber 110, 210, 310 may contain or may be associated with a heating element. Heating of the at least one wall of the processing chamber 110, 210, 310 may increase the temperature of the interior volume of the processing chamber 110, 210, 310. When the substrate 102, 202, 302 is received in the processing chamber 110, 210, 310, the increase in the temperature of the interior volume may encourage the formation of perovskite crystals / grains on the substrate 102, 202, 302.

[0064] Additionally or alternatively, the substrate holder 120, 220, 320 may be heatable. For example, the substrate holder 120, 220, 320 may contain a heating element. When the substrate is received in the processing chamber 110, 210, 310,heating of the substrate holder 120, 220, 320 is configured to heat the substrate 102, 202, 302 to facilitate perovskite crystal / grain growth on the substrate 110, 210, 310.

[0065] The temperature of the interior volume of the processing chamber 110, 210, 310 may reach a maximum temperature of around 400°C during use. This maximum temperature may be achieved by heating of the at least one wall and / or by heating of the substrate holder 120, 220, 320. In some embodiments, the temperature of the interior volume of the processing chamber 110, 210, 310 is in the range of around 30°C to around 250°C during use. In some embodiments, the temperature of the interior volume of the processing chamber 110, 210, 310 is in the range of around 30°C to around 300°C during use.

[0066] In the apparatus 100 illustrated in Fig. 1, the apparatus 100 further comprises a humidity chamber 130. The humidity chamber 130 may be configured to communicate with a humidity source 132 and receive humidity from the humidity source 132. The humidity may be steam or other form of water vapour, for example. In some embodiments, the humidity source 132 contains water which is heated and evaporated on the way to the humidity chamber 130 (or by the humidity chamber 130) to become steam. By receiving steam, the humidity levels in the humidity chamber 130 may be increased. The humidity chamber 130 may comprise a humidity chamber heater for adjusting a temperature of the humidity chamber 130.

[0067] When the substrate is received in the humidity chamber 130, the increased humidity and / or temperature may encourage the growth of perovskite crystals / grains on the substrate 102. This humidifying process may be referred to as a humidifying operation. In some embodiments, the humidifying operation in the humidity chamber 130 comprises applying heat and humidity to the substrate 102 to increase the size of the perovskite grains.

[0068] The humidity chamber 130 is configured to receive the substrate 102 from the processing chamber 110. The humidity chamber 130 may comprise a substrate holder 120. The substrate holder 120 in the humidity chamber 130 may not be height adjustable in the same way as described in relation to some embodiments of the substrate holder 120 in the processing chamber 110. The substrate holder 120 in the humidity chamber 130 may be heatable. In some embodiments, at least one wall of the humidity chamber 130 is heatable.

[0069] In some embodiments, the apparatus 100 further comprises a first transfer system 150 comprising a first passage 152. The first passage 152 may connect the processing chamber 110 and the humidity chamber 130. The first transfer system 150is configured to transfer the substrate 102 through the first passage 152 from the processing chamber 110 to the humidity chamber 130.

[0070] The first transfer system 150 may comprise a conveyor belt to facilitate the transfer of the substrate 102 through the first passage 152 from the processing chamber 110 to the humidity chamber 130. The first transfer system 150 may comprise one or more sealable doors to the processing chamber 110 and / or to the humidity chamber 130, so that heat loss and / or moisture loss from the chambers 110, 130 into the passage 152 is reduced. The first transfer system 150 may allow the substrate 102 to be transferred from the processing chamber 110 to the humidity chamber 130 without the substrate 102 being exposed to the outside atmosphere and / or environment. This may be advantageous as the perovskite may be unstable. Alternatively, the perovskite formed on the substrate 102 may be damaged or contaminated by exposure to the outside, for example by oxidation or dust. This damage or contamination may impede further perovskite growth or development, and affect the efficiency of the finished perovskite solar cell.

[0071] The substrate 102 may be loaded directly into the processing chamber 110. In some embodiments, the apparatus 100 further comprises a loading chamber 160. The loading chamber 160 is connected to, or may be considered to form part of, the first transfer system 150. Instead of loading the substrate 102 directly into the processing chamber 110, the loading chamber 160 is configured to receive the substrate 102 and transfer it via the first transfer system 150 into the processing chamber 110. The first transfer system 150 may subsequently transfer the substrate 102 from the processing chamber 110 into the humidity chamber 130 via the loading chamber 160. The loading chamber 160 may comprise one or more sealable doors, e.g. similar to the processing chamber 110 and / or the humidity chamber 130, so that heat loss and / or moisture loss from the chambers 110, 130 is reduced. The loading chamber 160 may be sealable to avoid the substrate 102 from being exposed to the outside atmosphere and / or environment during transfer of the substrate 102 between the processing chamber 110 and to the humidity chamber 130.

[0072] The carrier gas system 108 may be connected to the processing chamber 110 and / or the humidity chamber 130 to clear any leftover gas or vapour in a purging operation. The purging / vacuum system 109 may be connected to extract gas or vapour from the processing chamber 110 and / or the humidity chamber 130. The vacuum system 109 may be configured to independently operate with each chamber 110, 130, thereby reducing the pressure in one chamber without the affecting the pressure in the other chamber. The purging operation may occur before the substrate 102 istransferred from the processing chamber 110 to the humidity chamber 130.Alternatively or in combination, the purging operation may occur after the substrate 102 has completed the humidifying operation in the humidity chamber 130.

[0073] In the apparatus 200 illustrated in Fig. 2, the apparatus 200 further comprises a solvent chamber 240. The solvent chamber 240 may be configured to communicate with a solvent source 242 and receive solvent from the solvent source 242. The solvent chamber 240 may comprise a second outlet device 214 for dispensing the solvent into the solvent chamber 240. The second outlet device 214 may be fluidly connected to the solvent source 242. The second outlet device 214 may be a showerhead-like structure, comprising a spaced apart plurality of nozzles, configured to disperse the solvent through the solvent chamber 240. The solvent chamber 240 may comprise a substrate holder 220. The substrate holder 220 may be heatable. In some embodiments, at least one wall of the solvent chamber 240 is heatable.

[0074] The second outlet device 214 may be disposed directly above the substrate 202 so that the gravity assists the vapour deposition process. In contrast to a “horizontal” deposition process (where gravity generally does not assist the vapour deposition process), such a “vertical” deposition process can result in a more uniform thickness of vapour deposition, and therefore a more uniform thickness of perovskite layer formation on the substrate 202. A distance between the substrate holder 220 in the solvent chamber 240 and the second outlet device 214 may be varied, e.g. manually or automatically. Varying the distance between the substrate holder 220 and the second outlet device 214 may allow control of the intensity and / or spread of the solvent on the substrate 202.

[0075] In some embodiments, the substrate holder 220 is connected to the floor of the solvent chamber 240. The floor of the solvent chamber 240 may be raised to bring the substrate holder 220 closer to the second vapour source 214, thereby reducing the volume of the solvent chamber 240. Changing the volume of the solvent chamber 240 enables control of the solvent diffusion through the solvent chamber 240. For example, the solvent may diffuse more quickly through a smaller volume than a larger volume. The chemical reaction rate can be controlled by controlling the diffusion of the vapour through the solvent chamber 240.

[0076] The solvent may comprise dimethylformamide (DMF) or dimethyl sulfoxide (DMSO), for example. Exposing of the substrate 202 to a solvent in the solvent chamber 240 may be referred to as a finishing operation.

[0077] The solvent chamber 240 is configured to receive the substrate from the processing chamber 210. Unless noted otherwise, the processing chamber 210 is structurally and / or functionally identical to the processing chamber 110. During formation of the perovskite in the processing chamber 210, adjoining perovskite grains may have a rough boundary. Some perovskite grains may have lattice structure defects. The solvent may be configured to smoothen the boundary between adjoining perovskite grains. The solvent may be configured to address the lattice structure defects. This may improve the light conversion efficiency of the perovskite solar cell, for example.

[0078] In some embodiments, the apparatus 200 comprises a second transfer system 270 comprising a second passage 272. The second passage 272 may connect the processing chamber 210 and the solvent chamber 240. The second transfer system 270 is configured to transfer the substrate 202 through the second passage 272 from the processing chamber 210 to the solvent chamber 240. The second transfer system 270 may comprise a conveyor belt to facilitate the transfer of the substrate 202 through the second passage 272 from the processing chamber 210 to the solvent chamber 240. The second transfer system 270 may comprise one or more sealable doors to the processing chamber 210 and / or to the solvent chamber 240, so that heat loss and / or moisture loss from the chambers 210, 240 into the passage 272 is reduced. The second transfer system 270 may allow the substrate 202 to be transferred between the processing chamber 210 to the solvent chamber 240 without the substrate 202 being exposed to the outside atmosphere and / or environment. This may be advantageous as the perovskite formed on the substrate 202 may be damaged or contaminated by exposure to the outside, for example by oxidation or dust. This damage or contamination may impede further perovskite growth or development, and affect the efficiency of the finished perovskite solar cell.

[0079] In some embodiments, the apparatus 200 further comprises a loading chamber 260. The loading chamber 260 is connected to, or may be considered to form part of, the first transfer system 270. The loading chamber 260 is configured to receive the substrate 202 and transfer it via the second transfer system 270 into the processing chamber 210. The second transfer system 270 may subsequently transfer the substrate 202 from the processing chamber 210 into the solvent chamber 240 via the loading chamber 260. The loading chamber 260 may comprise one or more sealable doors, e.g. similar to the processing chamber 210 and / or the solvent chamber 240, so that heat loss and / or moisture loss from the chambers 210, 240 is reduced. The loading chamber 260 may be sealable to avoid the substrate 202 from being exposed to the outsideatmosphere and / or environment during transfer of the substrate 202 between the processing chamber 210 and to the solvent chamber 240.

[0080] The carrier gas system 208 may be connected to the processing chamber 210 and / or the solvent chamber 240 to clear any leftover gas or vapour in a purging operation. The purging / vacuum system 209 may be connected to extract gas or vapour from the processing chamber 210 and / or the solvent chamber 240. The vacuum system 209 may be configured to independently operate with each chamber 210, 240, thereby reducing the pressure in one chamber without the affecting the pressure in the other chamber. The purging operation may occur before the substrate 202 is transferred from the processing chamber 210 to the solvent chamber 240. Alternatively or in combination, the purging operation may occur after the substrate 202 has completed the finishing operation in the solvent chamber 240.

[0081] In the apparatus 300 illustrated in Fig. 3, the apparatus 300 comprises the processing chamber 310, a humidity chamber 330, and a solvent chamber 340. Unless noted otherwise, the processing chamber 310 is structurally and / or functionally identical to the processing chamber 110, 210. Unless noted otherwise, the humidity chamber 330 is structurally and / or functionally identical to the humidity chamber 130. For example, the humidity chamber 330 may be configured to communicate with a humidity source 332 and receive humidity from the humidity source 332. Unless noted otherwise, the solvent chamber 340 is structurally and / or functionally identical to the solvent chamber 240. For example, the solvent chamber 340 may be configured to communicate with a solvent source 342 and receive solvent from the solvent source 342. In some embodiments, at least one wall of the humidity chamber 330 is heatable. In some embodiments, at least one wall of the solvent chamber 340 is heatable.

[0082] In this apparatus 300, the humidity chamber 330 may be configured to receive the substrate 302 from the processing chamber 310 and the solvent chamber 340 may be configured to receive the substrate 302 from the humidity chamber 330. The humidity chamber 330 and / or the solvent chamber 340 may comprise respective substrate holders 320. The substrate holder 320 in the humidity chamber 330 and / or in the solvent chamber 340 may be heatable. The substrate holder 320 in the humidity chamber 330 may not be height adjustable in the same way as described in relation to some embodiments of the substrate holder 120, 220, 320 in the processing chamber 110, 210, 310 and / or in the solvent chamber 240, 340. The processing chamber 310 may comprise a first outlet device 312 for dispensing the first and / or second vapours into the processing chamber 310. The solvent chamber 340 may comprise a second outlet device 314 for dispensing the solvent into the solvent chamber 340.

[0083] The apparatus 300 may further comprise a third transfer system 380 comprising a third passage 382. The third passage 382 may connect the humidity chamber 330 and the solvent chamber 340 to facilitate movement of the substrate 302 therebetween. The third transfer system 380 may move the substrate 302 between the processing chamber 310, the humidity chamber 330, and the solvent chamber 340.

[0084] In some embodiments, the apparatus 300 further comprises a loading chamber 360. The loading chamber 360 is connected to, or may be considered to form part of, the third transfer system 380. The loading chamber 360 is configured to receive the substrate 302 and transfer it via the third transfer system 380 into the processing chamber 310, where the substrate 302 may, for example, undergo the pre-treatment and processing operations.

[0085] The third transfer system 380 may subsequently transfer the substrate 302 from the processing chamber 310 into the humidity chamber 330 via the loading chamber 360. In the humidity chamber 330 the substrate 302 may, for example, undergo the humidifying operation.

[0086] The third transfer system 380 may subsequently transfer the substrate 302 from the humidity chamber 330 into the solvent chamber 340 via the loading chamber 360. In the solvent chamber 340 the substrate 302 may, for example, undergo the finishing operation.

[0087] The third transfer system 380 may subsequently transfer the substrate 302 from the solvent chamber 340 into the processing chamber 310 via the loading chamber 360. In the processing chamber 310 the substrate 302 may, for example, undergo the post-processing operation.

[0088] The loading chamber 360 may comprise one or more sealable doors, e.g. similar to the processing chamber 310, the humidity chamber 330 and / or the solvent chamber 340, so that heat loss and / or moisture loss from the chambers 310, 330, 340 is reduced. The loading chamber 360 may be sealable to avoid the substrate 302 from being exposed to the outside atmosphere and / or environment during transfer of the substrate 302 between the processing chamber 310 and to the humidity chamber 330, between the humidity chamber 330 to the solvent chamber 340, and between the solvent chamber 340 and the processing chamber 310.

[0089] The carrier gas system 308 may be connected to the processing chamber 310, the humidity chamber 330 and / or the solvent chamber 340 to clear any leftover gas or vapour in a purging operation. The purging / vacuum system 309 may be connected to extract gas or vapour from the processing chamber 310, the humidity chamber 330and / or the solvent chamber 340. The vacuum system 309 may be configured to independently operate with each chamber 310, 330, 340 thereby reducing the pressure in each chamber without the affecting the pressure in the other chambers. The purging operation may occur before the substrate 302 is transferred between the chambers 310, 330, 340. Alternatively or in combination, the purging operation may occur after the substrate 302 has completed the associated operations in the chambers 310, 330, 340.

[0090] In an alternative embodiment of the apparatus 300 (not shown), the first transfer system 150, the second transfer system 270, and the third transfer system 380 cooperate to move the substrate 302 between the processing chamber 310, the humidity chamber 330, and the solvent chamber 340.

[0091] For example, the first transfer system 150 may be configured to transfer the substrate 302 through the first passage 152 from the processing chamber 310 to the humidity chamber 330. For example, this may be after the substrate 302 has completed the pre-treatment and processing operations in the processing chamber 310. The third transfer system 380 may be configured to transfer the substrate 302 through the third passage 382 from the humidity chamber 330 to the solvent chamber 340. For example, this may be after the substrate 302 has completed the humidifying operation in the humidity chamber 330. The second transfer system 270 may be configured to transfer the substrate through the second passage 272 from the solvent chamber 340 to the processing chamber 310. For example, this may be after the substrate 302 has completed the finishing operation in the solvent chamber 340. In the processing chamber 310, the substrate 302 may undergo the post-processing operation.

[0092] Fig. 4 shows a flowchart of a method of perovskite fabrication, 400. The method 400 comprises a pre-treatment operation 410. The method 400 may comprise a processing operation 420. The processing operation 420 may occur after the pretreatment operation 410. The method 400 may be a method of using the apparatus 300.

[0093] The method 400 may comprise a humidifying operation 430. The humidifying operation 430 may occur after the processing operation 420.

[0094] The method 400 may comprise a finishing operation 440. The finishing operation 440 may occur after the humidifying operation 430.

[0095] The method 400 may comprise a post-processing operation 450. The postprocessing operation 450 may occur after the finishing operation 440.

[0096] In some embodiments, the pre-treatment operation 410 comprises subjecting a substrate comprising a perovskite precursor film to a pre-treatment operation in aprocessing chamber. For example, the substrate may be the substrate 302, and the processing chamber may be the processing chamber 310.

[0097] The perovskite precursor film may be a lead iodide perovskite film formed by PVD, for example. The pre-treatment operation 410 may comprise exposing the substrate 302 to a first vapour comprising a first perovskite precursor. The pretreatment operation 410 may further comprise causing the first vapour and the perovskite precursor film to undergo a first chemical reaction resulting in an intermediate perovskite phase being formed on the substrate 302.

[0098] In some embodiments, the processing operation 420 comprises exposing the substrate to a second vapour comprising a second perovskite precursor. The processing operation 420 may further comprise causing the second vapour and the intermediate perovskite phase to undergo a second chemical reaction resulting in a final perovskite phase being formed on the substrate 302, wherein the final perovskite phase may comprise a plurality of perovskite grains.

[0099] In some embodiments, the humidifying operation 430 comprises applying heat and humidity to the substrate 302 to increase the size of the plurality of perovskite grains.

[0100] In some embodiments, the finishing operation 440 comprises applying a solvent to the substrate 302 to smoothen a boundary between adjoining perovskite grains.

[0101] In some embodiments, the post-processing operation 450 comprises exposing the substrate 302 to a passivation vapour to passivate the substrate 302.

[0102] It will be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. An apparatus for perovskite fabrication, the apparatus comprising:a chemical vapour deposition (CVD) processing chamber configured to communicate with a first vapour source and a passivation vapour source, wherein the CVD processing chamber is configured to receive: (i) a substrate; (ii) first vapour from the first vapour source; and (iii) passivation vapour from the passivation vapour source; anda heatable substrate holder disposed in the processing chamber, the heatable substrate holder configured to: (i) support the substrate; and (ii) heat the substrate to facilitate perovskite crystal growth on the substrate.

2. The apparatus of claim 1, further comprising a humidity chamber configured to communicate with a humidity source, wherein the humidity chamber is configured to receive the substrate from the CVD processing chamber, and wherein the humidity chamber is configured to receive humidity from the humidity source.

3. The apparatus of claim 2, further comprising a first transfer system comprising a first passage connecting the CVD processing chamber and the humidity chamber, wherein the first transfer system is configured to transfer the substrate through the first passage from the CVD processing chamber to the humidity chamber.

4. The apparatus of any one of claims 1 to 3, further comprising a solvent chamber configured to communicate with a solvent source.

5. The apparatus of claim 4, wherein the solvent chamber is configured to receive the substrate from the CVD processing chamber, and wherein the solvent chamber is configured to receive solvent from the solvent source.

6. The apparatus of claim 5, further comprising a second transfer system comprising a second passage connecting the CVD processing chamber and the solvent chamber, wherein the second transfer system is configured to transfer the substrate through the second passage from the CVD processing chamber to the solvent chamber.

7. The apparatus of claim 2 or claim 3, further comprising a solvent chamber configured to communicate with a solvent source and wherein the solvent chamber is configured to receive the substrate from the humidity chamber, and wherein the solvent chamber is configured to receive solvent from the solvent source.

8. The apparatus of claim 7, further comprising a third transfer system comprising a third passage connecting the humidity chamber and the solvent chamber, wherein:(i) the first transfer system is configured to transfer the substrate through the first passage from the CVD processing chamber to the humidity chamber; and (ii) the third transfer system is configured to transfer the substrate through the third passage from the humidity chamber to the solvent chamber.

9. The apparatus of any one of claims 1 to 8, wherein:the CVD processing chamber is configured to communicate with a second vapour source containing a second vapour, wherein the CVD processing chamber is configured to sequentially expose the substrate to the first vapour and the second vapour.

10. The apparatus of claim 7 or claim 8, further comprising a vacuum system connected to at least one of the CVD processing chamber, the humidity chamber, and / or the solvent chamber to remove vapour.

11. The apparatus of any one of claims 1 to 10, wherein the CVD processing chamber comprises a CVD processing chamber heater for adjusting a temperature of the CVD processing chamber.

12. The apparatus of claim 2 or claim 3, wherein the humidity chamber comprises a humidity chamber heater for adjusting a temperature of the humidity chamber.

13. The apparatus of any one of claims 1 to 12, wherein the CVD processing chamber comprises a first outlet device for dispensing the first vapour into the CVD processing chamber, the first outlet device being fluidly connected to the first vapour source.

14. The apparatus of claim 13, wherein a distance between the heatable substrate holder and the first outlet device is variable.

15. The apparatus of any one of claims 4 to 6, wherein the solvent chamber comprises a second outlet device for dispensing the solvent into the solvent chamber, the second outlet device being fluidly connected to the solvent source.

16. The apparatus of claim 15, wherein the solvent chamber further comprises a substrate holder for holding the substrate, wherein a distance between the substrate holder and the second outlet device is variable.

17. The apparatus of claim 9, further comprising a carrier gas system in fluid communication with the first vapour source and the second vapour source, wherein the carrier gas system is directly in fluid communication with the CVD processing chamber.

18. The apparatus of any one of claims 1 to 17, further comprising a set of valves for controlling a flow of the first vapour through the CVD processing chamber.

19. The apparatus of claim 18, further comprising a controller and a plurality of gas sensors, wherein operation of any one valve in the set of valves is controlled by the controller based on measurements from at least one of the plurality of gas sensors.

20. A method of perovskite fabrication, the method comprising:subjecting a substrate comprising a perovskite precursor film to a pretreatment operation;after the pre-treatment operation, subjecting the substrate to a processing operation;after the processing operation, subjecting the substrate to a humidifying operation;after the humidifying operation, subjecting the substrate to a finishing operation; andafter the finishing operation, subjecting the substrate to a post-processing operation;wherein the pre-treatment operation comprises:exposing the substrate to a first vapour comprising a first perovskite precursor;causing the first vapour and the perovskite precursor film to undergo a first chemical reaction resulting in an intermediate perovskite phase being formed on the substrate;wherein the processing operation comprises:exposing the substrate to a second vapour comprising a second perovskite precursor;causing the second vapour and the intermediate perovskite phase to undergo a second chemical reaction resulting in a final perovskite phase being formed on the substrate, the final perovskite phase comprising a plurality of perovskite grains;wherein the humidifying operation comprises applying heat and humidity to the substrate to increase the size of the plurality of perovskite grains;wherein the finishing operation comprises applying a solvent to the substrate to smoothen a boundary between adjoining perovskite grains; andwherein the post-processing operation comprises exposing the substrate to a passivation vapour to passivate the substrate.

21. The method of claim 20, wherein causing the first vapour and the perovskite precursor film to undergo a first chemical reaction comprises heating the substrate and / or the first vapour.

22. The method of claim 20 or claim 21, wherein causing the second vapour and the intermediate perovskite phase to undergo a second chemical reaction comprises heating the substrate and / or the second vapour.

23. The method of any one of claims 20 to 22, wherein the method is performed: (i) at atmospheric pressure; or (ii) at less than atmospheric pressure.

24. A method of perovskite fabrication, the method comprising use of the apparatus of any one of claims 1 to 19.

25. The steps, features, integers, compositions and / or compounds disclosed herein or indicated in the specification of this application individually or collectively, and any and all combinations of two or more of said steps or features.

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