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US-12623960-B2 - Composite material and preparation for the same

US12623960B2US 12623960 B2US12623960 B2US 12623960B2US-12623960-B2

Abstract

A composite material comprising a first layer of thermochromic perovskite; a second layer of antireflection material including an organic or inorganic polymer deposited on the first layer; and a third layer of hydrophobic material deposited on the second layer. A method for preparing the composite material is also addressed.

Inventors

  • Sai Liu
  • Chi Yan TSO

Assignees

  • CITY UNIVERSITY OF HONG KONG

Dates

Publication Date
20260512
Application Date
20230607

Claims (20)

  1. 1 . A composite material comprising: a first layer of thermochromic perovskite including a surface; a second layer of antireflection material including a surface and comprising an organic or inorganic polymer, the second layer is deposited on the surface of the first layer; and a third layer of hydrophobic material deposited on the surface of the second layer; wherein the second layer and the third layer are configured to permit a suitable amount of water vapor to reach the first layer to allow for hydration and dehydration of the first layer for supporting thermochromism of the first layer, and wherein each of the first, second, and third layers remains light-permeable after the thermochromism.
  2. 2 . The composite material as claimed in claim 1 , wherein the first layer comprises a substrate being made of glass or PET with a layer of thermochromic perovskite deposited thereon.
  3. 3 . The composite material as claimed in claim 2 , wherein the layer of thermochromic perovskite is 1.6 μm thick.
  4. 4 . The composite material as claimed in claim 1 , wherein the thermochromic perovskite comprises a halide perovskite-based compound having a general formula of A 4 BX 6 ·2H 2 O, with A being a monovalent organic cation, B being a bivalent cation, and X being one or more of a halide.
  5. 5 . The composite material as claimed in claim 4 , wherein A 4 BX 6 ·2H 2 O is reversibly changed to ABX 3 in response to a temperature change.
  6. 6 . The composite material as claimed in claim 5 , wherein A is selected from any one of C ⁢ H 3 ⁢ N ⁢ H 3 + and C ⁢ H ⁡ ( N ⁢ H 2 ) 2 + ; B is selected from any one of Pb 2+ , Sn 2+ , Ge 2+ , Mg 2+ , and Ca 2+ ; and X is selected from any one of I − , Br − , Cl − and a combination thereof.
  7. 7 . The composite material as claimed in claim 6 , wherein the halide perovskite-based compound has a general formula of (CH 3 NH 3 ) 4 PbI 6-x-y Br x Cl y ·2H 2 O, with x and y each being 0 or a positive integer, and x+y≤6.
  8. 8 . The composite material as claimed in claim 7 , wherein the halide perovskite-based compound is (CH 3 NH 3 ) 4 PbI 6-y Cl y ·2H 2 O, with y being 0 to 6.
  9. 9 . The composite material as claimed in claim 1 , wherein the antireflection material has a refractive index that is in between air and the thermochromic perovskite.
  10. 10 . The composite material as claimed in claim 9 , wherein the antireflection material comprises any one of epoxy, poly(methyl methacrylate), polyvinylpyrrolidone, poly(vinyl alcohol), polydimethylsiloxane, poly(acrylic acid), poly(acrylamide), poly(aniline), poly(ethylene oxide), poly(N-acryloxysuccinimide), poly(N-isopropylacrylamide), poly(N-isopropylmethacrylamide), poly(N-vinylcaprolactam), poly(N-vinylpyrrolidone), poly(methacrylic acid), poly(styrene sulfonic acid), polyurethane, poly(propylene oxide), perhydropolysilazane or a combination thereof.
  11. 11 . The composite material as claimed in claim 10 , wherein the antireflection material is perhydropolysilazane.
  12. 12 . The composite material as claimed in claim 11 , wherein the perhydropolysilazane takes the form of a homogenous inorganic film comprising SiO x /SiON x .
  13. 13 . The composite material as claimed in claim 1 , wherein the hydrophobic material comprises a superhydrophobic layer.
  14. 14 . The composite material as claimed in claim 13 , wherein the superhydrophobic layer comprises a layer of fluorinated nanocoating.
  15. 15 . The composite material as claimed in claim 14 , wherein the layer of fluorinated nanocoating is any one of fluorinated SiO 2 , fluorinated TiO 2 , and fluorinated ZnO.
  16. 16 . A method for preparing the composite material as claimed in claim 1 , comprising the steps of: coating a thermochromic perovskite on a substrate being made of glass or PET to form a first layer; coating an antireflection material on the first layer to form a second layer; and coating a silica-based nanoparticles on the second layer to form a third layer.
  17. 17 . The method as claimed in claim 16 , wherein the thermochromic perovskite is subjected to annealing after it is coated on the substrate to form the first layer.
  18. 18 . The method as claimed in claim 17 , wherein the thermochromic perovskite is a halide perovskite-based precursor of (CH 3 NH 3 ) 4 PbI 6-y Cl y ·2H 2 O, with y being 0 to 6, prepared by mixing CH 3 NH 3 I and PbCl 2 in a molar ratio of about 6.5:1.
  19. 19 . The method as claimed in claim 17 , wherein the annealing is at about 100° C. for about 1 hour.
  20. 20 . The method as claimed in claim 16 , wherein the antireflection material comprises a homogenous inorganic material that is solidified by curing after being spin-coated or blade-coated on the first layer.

Description

TECHNICAL FIELD The present invention relates a composite material for example particularly, but not exclusively, a thermochromic composite material comprising a thermochromic perovskite and a layer of material arranged to protect the thermochromic perovskite from excessive water contact; and a method for preparing the composite material. BACKGROUND OF THE INVENTION As a result of rapid urbanization, modern buildings are responsible for over 40% of the global primary energy consumption, causing over 30% of greenhouse gas emissions in cities. With stricter aesthetic requirements for buildings, an extremely high window-to-wall ratio has become a characteristic of modern architecture. However, both the unchangeable high transmittance under intense sunlight and the high U value of glass make windows the major sources of heat loss/gain among all building envelopes. Therefore, energy-saving smart windows whose solar transmittance can be dynamically regulated have recently attracted increasing attention to balance the goal of less energy consumption with the aesthetic demand for more glazing. One of the widely studied smart windows may be thermochromic smart windows, which generally makes use of the thermochromism of metal halide perovskites for managing buildings' energy usage and temperature. The color switch of thermochromic perovskites (T-Perovskites) generally relies on the H2O dissociation from and rebonding to the T-Perovskite layer, such as by the following chemical reaction: MAPbX3+3 MAX+2H2O↔MA4PbX6·2H2O where MA is CH3NH3+, and X is the halide anion. That said, on the one hand, water is essential to induce the thermochromic effect of T-Perovskites. On the other hand, water could degrade/corrode T-Perovskites especially when the T-Perovskites are continuously subjected to high-humidity environments or water droplets. In particular, excessive water may cause ultrahigh optical haze and blurry view through the T-Perovskites windows as a result of the presence of excessive MAX that would influence the crystallization process upon the color switch. In addition, the excessive water may also act as a solvent to dissolve the lead content in the T-Perovskites upon the thermochromic process, leading to lead leakage, threatening the environment and public health. Whilst there are reports of circumventing the problems above, those methods typically would either cause another problem or have to sacrifice the optical and transition performance of T-Perovskites. For example, one common method to protect T-Perovskites may be sealing them in a double-glazed window. However, this method requires tight packaging, making assembly of the window difficult, with a risk of leakage during long-term use. Alternatively, the T-Perovskites may be protected by covering with a protection layer, yet this method could result in insufficient water vapor supply to the T-Perovskites for enabling color switching. In another method, it may reduce the dimensions of the T-Perovskite to 2D. However, 2D T-Perovskites generally suffer from high Tc(>60° C.) and a long transition time (t>6 hours), which is basically not comparable with their 3D counterparts whose Tc values are near room temperature and t values are only several minutes. Thus, the development of durable and water-repellent T-Perovskite windows with outstanding optical and transition properties remains a challenge. The invention seeks to eliminate or at least to mitigate such shortcomings by providing a new or otherwise improved composite material, in particular, a composite material comprising a thermochromic perovskite and a layer of material arranged to protect the thermochromic perovskite from excessive water contact upon window application. SUMMARY OF THE INVENTION In a first aspect of the present invention, there is provided a composite material comprising: a first layer of thermochromic perovskite; a second layer of antireflection material comprising an organic or inorganic polymer deposited on the first layer; and a third layer of hydrophobic material deposited on the second layer. In an optional embodiment, the first layer comprises a substrate being made of glass or PET with a layer of thermochromic perovskite deposited thereon. Optionally, the thermochromic perovskite comprises a halide perovskite-based compound having a general formula of A4BX6·2H2O, with A being a monovalent organic cation, B being a bivalent cation, and X being one or more of a halide. It is optional that A4BX6·2H2O is reversibly changed to ABX3 in response to a temperature change. Optionally, A is selected from any one of CH3NH3+ and CH(NH2)2+; B is selected from any one of Pb2+, Sn2+, Ge2+, Mg2+, and Ca2+; and X is selected from any one of I−, Br−, Cl− and a combination thereof. In an optional embodiment, the halide perovskite-based compound has a general formula of (CH3NH3)4PbI6-x-yBrxCly·2H2O, with x and y each being 0 or a positive integer, and x+y≤6. In an embodiment of the invention, the halide