Patent Application
20210103197
The present invention is related to ABX3 perovskite particles and a reverse mode light valve; more specifically is related to the halide ABX3 perovskite particles and a reverse mode light control valve that can control the light transmission. The light control valve has the property of higher light transmittance when the power is turned off (OFF state) and lower light transmittance when the power is turned on (ON state), and such a device is preferably used for windows, lenses, or a light shutter such as a sunroof. The fascinating multifunctional smart windows exhibit promising features for a wide range of applications in buildings, airplanes, automobiles, etc. The present invention provides a new use for ABX3 perovskite material. Moreover, this reverse mode light valve has the advantages of high safety and low power consumption compared with the normal mode light valve.
Technically, a light valve is a device that can regulate the amount of light passing through a media like a water valve that can control the water flow. Window shade can be viewed as a light valve too. However, in this invention, the light valve is referred a device which can electronically control the light transmittance, and such a device is also scientifically referred as an electrochromic device. Depending on science behind an electrochromic device, it can be further classified as polymer dispersed liquid crystal (PDLC) (U.S. Pat. No. 3,585,381), electrochemical device (EC) (U.S. Pat. No. 9,581,877) and suspension particles display (SPD) (U.S. Pat. No. 6,606,185).
In a typical light valve, it is general dark color and transmits less light through when the power is turned off (OFF state), and it becomes light color and transmits more light through when the power is turned on (ON state); such an electrochromic device is thus referred to a normal mode light valve. The reverse mode light valve manipulates the light in a reversed way as to that of the normal mode light valve, and it is light color and transmits more light through when the power is turned off (OFF state) and becomes dark color and transmits less light through when the power is turned on (ON state). For the normal mode light valve which is less transparent when power is off, implies that once the power supply system fails, there is less visibility between two sides of the device, this may cause an adverse situation in certain circumstances. For example, the passengers of the vehicle would be difficult to spot the hazard situation outside when the electrochromic window lose its electric power. Contrasting to a normal mode light valve, the reverse mode light valve is more transparent at an OFF state, this eventually avoids the visibility problem in case of a power failing. Furthermore, passengers in most time need visibility for driving and for sightseeing, so the light valves (electrochromic windows here specifically) need to be transparent. To maintain this long period transparency, a normal mode light valve would require to be powered ON all the time, but a reserve mode light valve would simply be in OFF state without the need of power supplying. Obviously, the reverse mode light valve would provide energy saving most time comparing to the normal mode light valve.
Considering above merits of safety and energy saving, the reverse mode light valve should be highly demanded in applications, however, the development of such a reverse mode light valve is still a scientific challenge. Of a few reports related to reverse mode light valves found in prior arts, such as CN201710186038.6, WO/2015/022980, CN201420849573.7, U.S. Pat. No. 6,383,577, and the article published in Japanese Journal of Applied Physics, L557-L559, 43 (4B), 2004), they are all basing on polymer stabilized liquid crystal (PSLC) systems with very limited success.
This invention presents the method to use ABX3 perovskite particles to control the flux of light in a reverse mode electrochromic device, i.e., a reverse mode light valve (r-LV for short hereafter). Specifically, in this invention, the reverse mode light valve is referred a device that the light transmittance can be controlled by alternating current (AC). This reverse mode is more transparent when the power is turned off (OFF state) and becomes less transparent when the power is turned on (ON state). Such a device with controllable light switching and energy-saving advantages can be used as smart windows for transportation vehicles, architect buildings and other places where the light transmittance to be electronically controlled.
Perovskite, the name of the perovskite, originated from the Russian geologist Perovski and originally single-pointed the calcium titanate (CaTiO3) mineral. Later, crystals with similar structures were collectively referred to as perovskites. The cell structure of the halide ABX3 perovskite referred to in this patent is shown in
Among them, B atom and 6 X atoms form octahedral units, and 8 octahedral units occupy the position of the hexahedral apex centered on the A atom. This kind of material has a unique structure, giving it excellent optical, electrical, magnetic and thermodynamic properties, and is a new type of materials with attractive prospects.
In 2009, the ABX3 perovskite material was first reported for solar cells (J. Am. Chem. Soc. 131, 6050-6051, 2009). “Science” rated perovskite solar cells as one of the top 10 scientific breakthroughs in 2013. In January 2018, the Swiss Federal Institute of Technology in Lausanne set a new world record efficiency of 23.25% for a perovskite solar cell. In addition, the ABX3 perovskite material has been explored in other potential applications, such as LED (Light Emitting Diodes) (Tan, Zhi-Kuang, et al., Nature Nanotechnology, 9: 687-692, 2014), Lasers (Haiming Zhu, et al., Nature Mater., 14: 636-642, 2015), Photodetectors (Zhenqian Yang, et al., Adv. Materials, 30(8):1704333, 2018), Memristors (Zhengguo Xiao, et al., Advanced Electronic Materials, 2(7): 1600100, 2016), Photocatalytic (Sunghak Park, et al., Nature Energy, 2, 16185, 2016), Thermochromic (Jia Lin, et al., Nature Materials, 17, 261-267, 2018), and Ferroelectrics (Heng-Yun Ye, et al., Science, 2018, 361, 151-155).
Can ABX3 perovskite material be used to make a reverse mode light valve? No report related this application has been found in prior arts. Therefore, being the first time, the present invention discloses a technology how to use ABX3 perovskite particles to make a reverse mode light valve, and is opening a new application field for ABX3 perovskite materials.
This invention presents the method to use ABX3 perovskite particles to control the flux of light in a light control device (referred as a light valve). The present invention provides a new use of the ABX3 perovskite material, and method to make such a material. More specifically, the present invention further provides a reverse mode light valve(r-LV). This invented r-LV device comprises a liquid suspension having such a material of ABX3 perovskite particles, which can electronically control transmission of light in such way that it allows more light transmitted through when the power is turned off (OFF state) and less light transmitted through when the power is turned on (ON state). Still, ABX3 perovskite particles with a more specific chemical composition is specified, where A is at least one of Cs+, CH3NH3+, and Rb+, B is at least one of Pb2+, Ge2+, and Sn2+, and X is exclusively selected from one of halide anions including Cl−, Br−, or I−. As such a specified composition, the said ABX3 perovskite material is referred as halide ABX3 perovskite material. According to this invention, the referred halide ABX3 perovskite material is to be used in a form of particles, thus more specifically these particles used are referred as halide ABX3 perovskite particles. Still according to the invention, these halide ABX3 perovskite particles are characterized in that have a non-spherical morphology. Still further, the halide ABX3 perovskite particles morphology is at least one of a nanorod (one-dimensional); a nanosheet (two-dimensional); a cuboid, irregular (three-dimensional).
According to this invention, the liquid suspension, which is used as a liquid medium to suspend the ABX3 perovskite particles, comprises one or more a mineral resistive material, a synthetic resistive material, and a vegetable oil.
According to this invention as illustrated in
The present invention provides a new use for halide ABX3 perovskite particles to control the flux of light in a light control device in a reverse mode, thus referred as a reverse light valve (r-LV).
Therefore, being the first time, the present invention provides a novel use of the ABX3 perovskite particles in a reverse mode light control device (r-LV). According to the present invention, the invented r-LV comprises a liquid suspension having such a material of ABX3 perovskite particles, which can electronically control transmission of light in such way that it allows more light transmitted through when the power is turned off (OFF state) and less light transmitted through when the power is turned on (ON state). Still, ABX3 perovskite particles with a more specific chemical composition is disclosed, where A is at least one of Cs+, CH3NH3+, and Rb+, B is at least one of Pb2+, Ge2+, and Sn2+, and X is at least one of halide anions selected from Cl−, Br−, or I−. Accordingly, the specified ABX3 perovskite material is referred as halide ABX3 perovskite material. According to this invention, the referred halide ABX3 perovskite material is to be used in a form of particles, thus more specifically these particles used are referred as halide ABX3 perovskite particles. Still according to the invention, these halide ABX3 perovskite particles are characterized in that have a non-spherical morphology. Still further, the halide ABX3 perovskite particles morphology is at least one of a nanorod (one-dimensional); a nanosheet (two-dimensional); a cuboid, irregular (three-dimensional).
As illustrated in
According to the invention, the said ABX3 perovskite particles shall have such a characteristic that the said ABX3 perovskite particles are capable of being polarized under an electric field, and still the effective maximum surface of the polarized ABX3 perovskite particles is perpendicular to direction of the electric field. In one embedment, the said ABX3 perovskite particles are nanosheets, after being polarized under an electric field, the surface of the large specific surface of the nanosheets is oriented to be perpendicular to the direction of the electric field.
According to this invention, the said liquid suspension (300), which is used as a liquid medium to suspend the ABX3 perovskite particles, comprises one or more non-aqueous, electrically resistive liquids. Such a liquid or a liquid mixture, referring as the suspension medium, can maintain the suspended ABX3 perovskite particles in gravitational equilibrium.
More specifically in this invention, the liquid suspension (300) comprises one or more a mineral resistive material, a synthetic resistive material, a vegetable oil. Mineral resistive materials, such as transformer oils; synthetic resistive materials, such as silicone oils, fluorocarbon organic compounds, plasticizers (such as Dioctyl phthalate, Dibutyl phthalate, Diisobutyl phthalate, Triisodecyl trimellitate (TDTM) etc.), dodecylbenzene, polybutene oil, etc.; vegetable oils, such as castor oil, soybean oil, rapeseed oil, etc., are good liquid suspension mediums. As a broad scope, the liquid suspension medium used in the light valve of the present invention can be any liquid light valve suspension known in the art and can be formulated according to techniques well known to those skilled in the art.
According to this invention as illustrated in
Since the halide ABX3 perovskite particles are sensitive to moisture and oxygen, the liquid suspension containing the said halide ABX3 perovskite particles sandwiched between the two transparent electrodes is preferably to be sealed with a resistive material, such as epoxy resin, etc. An alternating current is thus applied through the transparent electrodes (110) to control the light transmittance through the assembled r-LV, and the voltage of such an alternating current is preferably in the range of 5-500 V, more preferably in a range of 30-220 V, which can be easily achieved by a common transformer.
The invention will now be described in more detail with reference to the following examples. However, these examples are given for illustration only and are not intended to limit the scope of the present invention. All chemicals used in the examples are purchased from Sigma-Aldrich Company unless otherwise specified. In all these examples, all parts and percentages are by weight unless otherwise noted. The light transmittance and absorption spectrum of the r-LV device was measured by an Oceanview spectrometer.
Cesium carbonate (Cs2CO3, 4.07 g) was loaded into a 250 mL 3-neck flask along with octadecene (ODE, 50 mL) and oleic acid (11.088 g), and the mixture was dried for 1 h at 120° C. and then heated under Argon (Ar) to 150° C. until all Cs2CO3 reacted with oleic acid. The obtained Cs-Oleate may precipitate out of ODE at room temperature, and it can be preheated to make it soluble before further using.
N,N-dimethylformamide (DMF, 100 mL) and lead iodide (PbI2, 2.305 g) were charged into a 250 mL flask. Oleic acid (0.438 g) and octylamine (2.339 g) were added. After complete solubilization of PbI2, 5 mL Cs-Oleate solution was added (prepared as described in Example 1). Then, the resulted solution was added into a 5 L flask along with 4200 mL of toluene. Subsequently, the resulted solution was centrifuged at 5000 G for 1.5 hours and the supernatant was discarded to yield the light control CsPbI3 nanosheets. Finally, the CsPbI3 nanosheets were further dispersed with 500 mL of toluene, mixed well with shaking and sonication (referring as LCP-Example-2).
In the same manner as in Example 2, but 1.835 g of PbBr2 was used instead of 2.305 g of PbI2. A toluene mixture containing CsPbBr3 nanosheets is obtained and referred as LCP-Example-3.
Into a 250 mL round bottom glass flask was weighted 10 g of Triisodecyltrimellitate (TDTM), then the LCP-Example-2 prepared in the Example 2 was added in portions. After thoroughly mixing the resulted suspension by shaking, toluene was subsequently removed by a rotary evaporator for 3 hours at 80° C. to yield a r-LV suspension containing CsPbI3 nanosheets, which is referred as r-LV Suspension Example-4.
Into a 250 mL round bottom glass flask was weighted 10 g of silicone oil, then the LCP-Example-3 prepared in the Example 3 was added in portions. After thoroughly mixing the resulted suspension by shaking, toluene was subsequently removed by a rotary evaporator for 3 hours at 80° C. to yield a r-LV suspension containing CsPbBr3 nanosheets, which is referred as r-LV Suspension Example-5.
In this example, a layer of the r-LV Suspension—Example 4 made in Example 4 at a thickness of 200 um was sealed between two transparent electrodes of ITO conductive glass using epoxy resin to produce a light valve referring as r-LV Device-6. When no electric voltage was applied (OFF State), r-LV Device-6 exhibited an orange tint and light transmission was measured to be 19.4%. When it was electrically activated using 220 Volts AC at 50 Hz (ON State), the r-LV Device-6 became darker and light transmission was measured to be 7.0% only. Table 1 summaries these results. Further,
In this example, a layer of the r-LV Suspension—Example 5 made in Example 5 at a thickness of 180 um was sealed between two transparent electrodes of ITO conductive glass using epoxy resin to produce a light valve referring as r-LV Device-7. When no electric voltage was applied (OFF State), r-LV Device-7 exhibited an orange tint and light transmission was measured to be 25.1%. When it was electrically activated using 220 Volts AC at 50 Hz (ON State), the r-LV Device-7 became darker and light transmission was measured to be 12.5% only as listed in Table 1.
