A reflective visible / thermal infrared separation regulation electrochromic thin film device

Abstract

The application discloses a reflective visible light / thermal infrared separation regulation and control electrochromic thin film device, and belongs to the technical field of wide-band electrochromic camouflage. The reflective visible light / thermal infrared separation regulation and control electrochromic thin film device comprises, from top to bottom, a visible light-thermal infrared transparent packaging thin film, a visible light / thermal infrared electrochromic working electrode, an electrolyte layer, a counter electrode and a packaging thin film; wherein the visible light / thermal infrared electrochromic working electrode comprises a patterned interdigital metal conductive layer and an electrochromic functional layer formed on the interdigital metal conductive layer; the electrochromic functional layer is an interdigital structure formed by a first electrochromic thin film and a second electrochromic thin film and is the same as the interdigital metal conductive layer. By applying a voltage to the different electrochromic thin films in the working electrode and the counter electrode, the coloration / bleaching and high / low infrared emissivity states are regulated and controlled, and the effect of visible light / thermal infrared separation regulation and control is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wide-band electrochromic camouflage, and particularly relates to a reflective visible light / thermal infrared separation regulation electrochromic film device. BACKGROUND

[0002] In recent years, with the rapid development of detection technology, a multi-optical band real-time target detection and analysis technology based on optical, electronic, infrared and other sensor detection has been formed, and the target is identified by detecting the color and infrared radiation characteristic difference between the target and the background environment. Therefore, a single color cannot meet the existing camouflage requirements. In view of this situation, the wide-band electrochromic technology has good plan adaptability, and has the characteristics of electric response optical property regulation. With the development of the technology, a wide-band electrochromic material such as a conductive polymer has been found, which can realize visible light color change and thermal infrared radiation regulation. However, due to the variability of the natural environment, there are different color changes such as yellow, light green, dark green and blue. At the same time, due to the inconsistency of the background infrared radiation characteristics, the same detection target and background will present different infrared thermal image distinguishability in different background environments such as land, sea and sky. Therefore, an electrochromic device with visible light color and thermal infrared radiation separation regulation performance is needed to adapt to different environmental backgrounds, so as to have good application potential in the field of intelligent camouflage.

[0003] Currently, due to ion injection and extraction under the color changing mechanism of electrochromic devices and the change of chemical structure of materials, it is difficult to achieve visible light and thermal infrared separation control in wide-band electrochromic technology, that is, the existing visible light and thermal infrared emissivity states are coupled with each other, and a single electrochromic device can only realize two modes of visible light coloring / thermal infrared high emissivity and visible light bleaching / thermal infrared low emissivity or two modes of visible light coloring / thermal infrared low emissivity and visible light bleaching / thermal high emissivity. The existing transmissive device uses a second electrochromic layer deposited on a single electrochromic layer or controls the depth and concentration of ion injection in the double electrochromic layer to realize the separation control of visible light and infrared. However, the transmissive electrochromic device for modulating transmittance will inevitably produce unnecessary infrared absorption in the second electrochromic layer, ion storage layer or electrolyte layer due to the inherent properties of transparent conductive electrodes such as FTO and ITO, electrolyte organic solvents and electrochromic layers, which significantly affects the infrared transmittance control performance of the electrochromic device. Therefore, with the development of detection technology, it is necessary to develop a separate control electrochromic technology with visible light color and thermal infrared radiation control performance, and to exclude unnecessary infrared absorption between the electrolyte layer and the electrochromic layer, reasonably design the electrode structure of the electrochromic working electrode, and develop a visible light / thermal infrared separate control electrochromic device. This will help the electrochromic device to be better applied in military camouflage and electronic skin, so that the device can better adapt to different color and thermal infrared radiation environments and realize the color changing effect like "chameleon skin". SUMMARY

[0004] The purpose of the present application is to provide a reflective visible light / thermal infrared separate control electrochromic thin film device to solve the problem that the existing wide-band electrochromic device does not have the function of visible light color and thermal infrared radiation separation control.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] A reflective visible light / thermal infrared separate control electrochromic thin film device, comprising a visible light-thermal infrared transparent packaging film, a visible light / thermal infrared electrochromic working electrode, an electrolyte layer, a counter electrode and a packaging film arranged in sequence from top to bottom.

[0007] The visible light / thermal infrared electrochromic working electrode comprises a patterned interdigital metal conductive layer and an electrochromic functional layer formed on the interdigital metal conductive layer; the electrochromic functional layer is an interdigital structure formed by a first electrochromic thin film and a second electrochromic thin film, wherein the first electrochromic thin film is located on one interdigital finger of the interdigital metal conductive layer, and the second electrochromic thin film is located on the other interdigital finger of the interdigital metal conductive layer.

[0008] Further, the material of the first electrochromic film is a material that has dynamic color regulation in the 350-780 nm visible light band and maintains a constant transmittance of greater than 80% in the 2.5-15 μm thermal infrared band; the material of the second electrochromic film is a material that has the same or similar visible light color regulation as the material of the first electrochromic film and has infrared regulation function in the 2.5-15 μm thermal infrared band, or is a material that only has infrared regulation function in the 2.5-15 μm thermal infrared band.

[0009] Further, the counter electrode includes a metal conductive layer and an ion storage functional layer formed on the metal conductive layer; the metal conductive layer is an interdigital structure same as that of the interdigital metal conductive layer in the working electrode or is a complete metal film. When the metal conductive layer is an interdigital structure, the ion storage functional layer is an interdigital structure formed by the first electrochromic film and the second electrochromic film; when the metal conductive layer is a complete metal film, the ion storage functional layer is a complete first electrochromic film or a complete second electrochromic film.

[0010] Further, by applying voltage to the working electrode and the counter electrode, coloration / bleaching and high / low infrared emissivity state regulation can be achieved.

[0011] Further, the infrared regulation function of the material of the second electrochromic film can be achieved by regulating infrared emissivity or actual temperature. When the material of the second electrochromic film achieves the infrared regulation function by regulating infrared emissivity, the counter electrode and the ion storage functional layer are interdigital structures, the regulation of visible light color is achieved by applying voltage between a group of interdigitations of the visible light / thermal infrared electrochromic working electrode and the counter electrode, the regulation of infrared emissivity or infrared emissivity and color is achieved by applying voltage between another group of interdigitations of the visible light / thermal infrared electrochromic working electrode and the counter electrode; when the material of the second electrochromic film achieves the infrared regulation function by actual temperature (Joule heat), the counter electrode and the ion storage functional layer are complete film structures, the regulation of visible light color is achieved by applying voltage between an interdigitations of the visible light / thermal infrared electrochromic working electrode and the complete counter electrode, the regulation of infrared is achieved by applying voltage across the two ends of the interdigitations of the visible light / thermal infrared electrochromic working electrode.

[0012] Further, the aspect ratio of the interdigitations in the interdigital metal conductive layer is greater than or equal to 10.

[0013] Further, the interdigital metal conductive layer comprises a porous substrate and a conductive film formed on the porous substrate by electron beam evaporation or magnetron sputtering; the porous substrate is a porous polyamide-66 film, a polytetrafluoroethylene film, a fluorinated ethylene-propylene film, a polyester film or a cellulose film, and the conductive film is one or more of gold, silver, platinum, titanium and aluminum, and the thickness is 0.05-50 microns.

[0014] Further, the material of the first electrochromic film is Prussian blue, titanium dioxide or tungsten oxide; the second electrochromic film material which has the same or similar color as the first electrochromic film material and can control the visible light color and has infrared regulation function in the 2.5-15 micron thermal infrared band can be selected from polyaniline, polythiophene, polypyrrole and derivatives thereof, and the thickness is 0.5-500 microns; the second electrochromic film material which only has infrared regulation function in the 2.5-15 micron thermal infrared band can be selected from MXene materials and graphene, and the thickness is 0.5-500 microns.

[0015] Further, the visible light-thermal infrared transparent packaging film is a window material film of polyethylene, polypropylene, calcium fluoride, zinc sulfide, zinc selenide, germanium, etc., and the thickness is 0.01-1 mm.

[0016] Further, the electrolyte layer comprises a solvent, a skeleton polymer and an electrolyte; the solvent is one or more of propylene carbonate, fluoroethylene carbonate, ethyl acetate and acetonitrile, the skeleton polymer is one or more of polymethyl methacrylate, polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride and poly(vinylidene fluoride-co-hexafluoroethylene), and the electrolyte is one or more of ionic liquid, lithium salt, sodium salt and protonic acid.

[0017] Further, the packaging film is a polymer film of polypropylene, polytetrafluoroethylene, high-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene and polyester, or an inorganic film of calcium fluoride, zinc sulfide, germanium and high-aluminum silicon glass, and the thickness is 0.01-1 mm.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1. The present application provides a reflective visible light / thermal infrared separation regulation electrochromic film device, the working electrode is a fine stripe interdigital pattern structure with an aspect ratio greater than 10, the first electrochromic film and the second electrochromic film are arranged on different interdigital structures, so that the device is regarded as a complete plane when being detected by a remote visible light or thermal infrared, thereby achieving the purpose of deceiving the detector.

[0020] 2. This invention achieves the control of coloring / fading and high / low infrared emissivity states by applying voltage to different electrochromic films in the working electrode and to the counter electrode, thereby achieving the effect of visible light / thermal infrared separation and control.

[0021] 3. In this invention, the first electrochromic film and the second electrochromic film are placed on the same layer in an interdigitated structure and placed on the top layer of the device, which effectively avoids the mutual influence of interlayer optical absorption and maximizes the color-changing performance. Attached Figure Description

[0022] Figure 1 A schematic diagram of the structure of the interdigitated metal conductive layer in a reflective visible light / thermal infrared separation-controlled electrochromic thin film device provided by the present invention;

[0023] Figure 2 This is a schematic diagram of the structure of the reflective visible light / thermal infrared separation-controlled electrochromic thin film device provided in Example 1;

[0024] Figure 3 This is a schematic diagram of the structure of the reflective visible light / thermal infrared separation-controlled electrochromic thin film device provided in Example 2;

[0025] Figure 4 Visible light color modulation diagram of the actual reflective visible light / thermal infrared separated modulated electrochromic thin film device provided in Example 1;

[0026] Figure 5 The thermal infrared radiation modulation diagram of the actual reflective visible light / thermal infrared separated modulated electrochromic thin film device provided in Example 1. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0028] Example 1

[0029] like Figure 2 The diagram shown is a schematic representation of the reflective visible light / thermal infrared separation-controlled electrochromic thin-film device provided in Example 1. It includes, from top to bottom, a visible light / thermal infrared transparent encapsulation film, a visible light / thermal infrared electrochromic working electrode, an electrolyte layer, a counter electrode, and an encapsulation film. The first electrochromic film in the working electrode is a Prussian blue film, and the second electrochromic film is a polyaniline derivative film. The conductive film in the interdigitated metal conductive layer is gold. The first electrochromic film in the ion storage layer of the counter electrode is a Prussian blue film, and the second electrochromic film is a polyaniline derivative film.

[0030] The preparation process of the reflective visible light / thermal infrared separation regulation electrochromic thin film device provided in Example 1 is as follows:

[0031] Step 1. The interdigital metal conductive layer is designed as an interdigital structure formed by two comb structures with an area ratio of 1:1, wherein the stripe width of the interdigital structure is about 0.04 mm, so that the two parts of the stripe can be regarded as a plane at a certain distance apart;

[0032] Step 2. A continuous metal conductive layer is deposited on the surface of the porous substrate by an electron beam evaporation method, and an infrared laser engraving machine is used to engrave a path of 0.01 mm on the surface of the continuous metal conductive layer at a power of 30 W, to obtain a patterned interdigital metal conductive layer;

[0033] Step 3. Deionized water and HCl are added to a reaction container, and then KCl, FeCl3 6H2O and K3[Fe(CN)6] are sequentially added, and the mixture is stirred at room temperature for 1 h to obtain a uniform solution; then a three-electrode method is used to deposit a uniform Prussian blue film on one interdigital electrode of the interdigital metal conductive layer at -15 μA / cm 2 for 800 s;

[0034] Step 4. Deionized water and H2SO4 are added to a reaction container, and then triphenylamine and aniline are sequentially added, and the mixture is stirred at room temperature for 12 h to obtain a uniform solution; then a three-electrode method is used to deposit a uniform polyaniline derivative film on the other interdigital electrode of the interdigital metal conductive layer at a constant voltage of 0.60 V for 100 s;

[0035] Step 5. Lithium perchlorate, 1-ethyl-3-methylimidazolium tetrafluoroborate and polymethyl methacrylate are added to a reaction container, and then propylene carbonate and fluoroethylene carbonate are sequentially added, and the mixture is stirred at 60°C for 5 h to obtain an electrolyte layer;

[0036] Step 6. The working electrode and the counter electrode which are completely identical to the working electrode are packaged by a “roll-to-roll” hot pressing method, and then the electrolyte layer is coated on the back of the packaged visible light / thermal infrared electrochromic working electrode and counter electrode, and the visible light / thermal infrared electrochromic working electrode, the electrolyte layer and the counter electrode are stacked in the order of “visible light / thermal infrared electrochromic working electrode / electrolyte layer / counter electrode” to obtain a reflective visible light / thermal infrared separation regulation electrochromic thin film device.

[0037] The working principle of the reflective visible light / thermal infrared separation regulation electrochromic thin film device of Example 1 is as follows:

[0038] At an applied voltage of -1.6V, the Prussian blue of the first electrochromic film undergoes a lattice structure change due to cation implantation, resulting in a colorless and transparent state. This color, combined with the color of the interdigitated metal conductive layer, produces a yellow hue. At an applied voltage of +0.6V, the Prussian blue film undergoes a lattice structure change due to cation desorption, resulting in a blue hue. This color, combined with the yellow hue of the interdigitated metal conductive layer, produces a green hue. At an applied voltage of +0.6V, the polyaniline derivative of the second electrochromic film undergoes a reversible oxidation reaction, resulting in a change in its molecular structure and the generation of a polaron / bipolaron structure, exhibiting a green hue and a high emission state. At an applied voltage of -1.6V, the polyaniline derivative film undergoes a reversible reduction reaction, resulting in a change in its molecular structure and the elimination of the polaron / bipolaron structure, resulting in a colorless, transparent state and a low emission state. This color, combined with the color of the interdigitated metal conductive layer, produces a yellow hue and other colors. At a constant electrolyte concentration, the first / second electrochromic films can be subjected to positive / negative, positive / positive, negative / negative, or negative / positive external voltages, respectively, to achieve transitions between different control states. Due to the small stripe width of the interdigital pattern, the first / second electrochromic films exhibit similar effects to their independent continuous electrochromic films during observation, ultimately achieving separate control of visible light and thermal infrared radiation.

[0039] Example 2

[0040] like Figure 3 The diagram shown is a schematic representation of the reflective visible light / thermal infrared separation-controlled electrochromic thin-film device provided in Example 2. It includes, from top to bottom, a visible light / thermal infrared transparent encapsulation film, a visible light / thermal infrared electrochromic working electrode, an electrolyte layer, a counter electrode, and an encapsulation film. The first electrochromic film in the working electrode is a Prussian blue film, and the second electrochromic film is an MXene film. The conductive film in the interdigitated metal conductive layer is gold. The electrochromic film in the ion storage layer of the counter electrode is a Prussian blue film.

[0041] The fabrication process of the reflective visible light / thermal infrared separation-controlled electrochromic thin film device provided in Example 2 is as follows:

[0042] Step 1. The interdigitated metal conductive layer is designed as an interdigitated structure formed by two comb-like structures with an area ratio of 1:1. The stripe width of the interdigitated structure is about 0.04 mm, so that the two stripes can be regarded as a plane when they are a certain distance apart.

[0043] Step 2. A continuous metal conductive layer is deposited on the surface of a porous substrate by electron beam evaporation. Then, an infrared laser etching machine is used at a power of 30W to etch a path with a width of 0.01mm on the surface of the continuous metal conductive layer to obtain a patterned interdigitated metal conductive layer.

[0044] Step 3. Deionized water and HCl were added into the reaction vessel, and then KCl, FeCl3 6H2O and K3[Fe(CN)6] were added in sequence, and a uniform solution was obtained after stirring at room temperature for 1 h; then a three-electrode method was used to deposit Prussian blue film on the gold conductive layer at -15 μA / cm2. 2 The Prussian blue film was deposited on one of the interdigital metal conductive layers for 800 s to obtain a uniform Prussian blue film on the interdigital metal conductive layer;

[0045] Step 4. HF and HCl were added into the reaction vessel, and then Ti3AlC2 powder was added in small amounts in sequence, and the mixture was stirred and heated at 45℃ for 12-24 h; the mixture was centrifuged and washed with deionized water for multiple times until the supernatant was close to neutral, and the precipitate was collected; then the collected precipitate was added into distilled water, and LiCl was added, and the mixture was stirred at room temperature for 12-24 h; single-layer Ti3C2T x MXene was obtained by multiple expansion and centrifugation, and the upper suspension was collected by low-speed centrifugation to obtain single-layer / few-layer Ti3C2T x MXene dispersion liquid;

[0046] Step 5. The above Ti3C2T x MXene dispersion liquid and deionized water were mixed uniformly, and a self-supporting MXene film was obtained by vacuum filtration device;

[0047] Step 6. Lithium perchlorate, 1-ethyl-3-methylimidazolium tetrafluoroborate and polymethyl methacrylate were added into the reaction vessel, and then propylene carbonate and fluoroethylene carbonate were added in sequence, and the mixture was stirred at 60℃ for 5 h to obtain an electrolyte layer;

[0048] Step 7. The Prussian blue film deposited on the gold conductive layer was used as a counter electrode, the working electrode and the counter electrode were packaged by a "roll-to-roll" hot pressing method, and then the electrolyte layer was coated on the back of the packaged visible light / thermal infrared electrochromic working electrode and counter electrode, and the visible light / thermal infrared electrochromic working electrode / electrolyte layer / counter electrode was stacked in sequence to obtain a reflective type visible light / thermal infrared separation regulation electrochromic film device.

[0049] The working principle of the reflective type visible light / thermal infrared separation regulation electrochromic film device of Example 2 is as follows:

[0050] When the applied voltage is-1.6V, the lattice structure of the first electrochromic film of Prussian blue changes due to the injection of cations, and it presents colorless transparency, and after superimposed with the color of the interdigital metal conductive layer, it presents yellow; when the applied voltage is +0.6V, the lattice structure of the Prussian blue film changes due to the extraction of cations, and it presents blue, and after superimposed with the yellow of the interdigital metal conductive layer, it presents green. When the applied voltage is 3.0V, the MXene of the second electrochromic film can rapidly heat up due to the Joule heating effect, and according to the Stefan-Boltzmann law, the thermal infrared radiation power of the MXene film rises; after the applied voltage is removed, due to the low emissivity characteristics and planar thermal conductivity of the MXene film, the surface will rapidly dissipate heat and present low thermal infrared radiation. Since the MXene film is generated by the Joule heating effect by applying voltage on the electrode surface, the first / second electrochromic film can be applied with positive / negative, positive / positive, negative / negative or negative / positive voltage and realize the transition of different regulation states. Since the stripe width of the interdigital pattern is small, the first / second electrochromic film presents similar effects compared with its independent continuous electrochromic film when observed, and finally realizes the separation and regulation of visible light and thermal infrared radiation.

Claims

1. A reflective visible / thermal infrared separation modulating electrochromic thin film device, characterized in that, The visible light-thermal infrared transparent packaging film, the visible light / thermal infrared electrochromic working electrode, the electrolyte layer, the counter electrode and the packaging film are sequentially arranged from top to bottom. The visible light / thermal infrared electrochromic working electrode comprises a patterned interdigital metal conductive layer and an electrochromic functional layer formed on the interdigital metal conductive layer; the electrochromic functional layer is an interdigital structure formed by a first electrochromic film and a second electrochromic film, wherein the first electrochromic film is located on one interdigital electrode of the interdigital metal conductive layer, and the second electrochromic film is located on another interdigital electrode of the interdigital metal conductive layer. The material of the first electrochromic film has dynamic color regulation in the visible light wave band of 350-780 nm and transmittance of greater than 80% in the thermal infrared wave band; the material of the second electrochromic film is the same as or the same color system as the material of the first electrochromic film and has visible light color regulation in the visible light wave band of 2.5-15 The material has transmittance of greater than 80% in the thermal infrared wave band; the material of the second electrochromic film is the same as or the same color system as the material of the first electrochromic film and has visible light color regulation in the visible light wave band of 2.5-15 The material has transmittance of greater than 80% in the thermal infrared wave band; the material of the second electrochromic film is the same as or the same color system as the material of the first electrochromic film and has visible light color regulation in the visible light wave band of 2.5-15 The material has transmittance of greater than 80% in the thermal infrared wave band.

2. The reflective visible / thermal infrared separation modulating electrochromic thin film device according to claim 1, characterized in that, The counter electrode comprises a metal conductive layer and an ion storage functional layer formed on the metal conductive layer; the metal conductive layer is an interdigital structure same as the interdigital metal conductive layer in the working electrode or is a complete metal film.

3. The reflective visible / thermal infrared separation modulating electrochromic thin film device of claim 1, wherein, When the second electrochromic film material realizes the infrared regulation function by regulating the infrared emissivity, the counter electrode and the ion storage functional layer are in an interdigital structure, the visible light color is regulated by applying a voltage between a group of interdigital electrodes of the visible light / thermal infrared electrochromic working electrode and the counter electrode, and the infrared emissivity or the infrared emissivity and color are regulated by applying a voltage between another group of interdigital electrodes of the visible light / thermal infrared electrochromic working electrode and the counter electrode; when the second electrochromic film material realizes the infrared regulation function by temperature, the counter electrode and the ion storage functional layer are in a complete film structure, the visible light color is regulated by applying a voltage between one interdigital electrode of the visible light / thermal infrared electrochromic working electrode and the complete counter electrode, and the infrared is regulated by applying a voltage at two ends of one interdigital electrode of the visible light / thermal infrared electrochromic working electrode. 4.The reflective visible / thermal infrared separation regulated electrochromic thin film device of claim 1, wherein, The length-width ratio of the interdigital electrode in the interdigital metal conductive layer is greater than or equal to 10.

5. The reflective visible / thermal infrared separation modulating electrochromic thin film device of claim 1, wherein, The interdigital metal conductive layer comprises a porous substrate and a conductive film formed on the porous substrate by an electron beam evaporation method or a magnetron sputtering method; the porous substrate is a porous polyamide-66 film, a polytetrafluoroethylene film, a fluorinated ethylene-propylene film, a polyester film or a cellulose film, and the conductive film is one or more of gold, silver, platinum, titanium and aluminum.

6. The reflective visible / thermal infrared separation modulating electrochromic thin film device of claim 1, wherein The material of the first electrochromic film is Prussian blue, titanium dioxide or tungsten oxide; the visible light color modulation is the same as or in the same color system as the first electrochromic film material and is in the range of 2.5~15 The second electrochromic film material with infrared modulation function in the thermal infrared wave band is polyaniline, polythiophene, polypyrrole and derivatives thereof; only with infrared modulation function in the range of 2.5~15 The second electrochromic film material with infrared modulation function in the thermal infrared wave band is MXene material, graphene.

7. The reflective visible / thermal infrared separation modulating electrochromic thin film device of claim 1, wherein The visible light-thermal infrared transparent packaging film is polyethylene, polypropylene, fluorinated calcium, zinc sulfide, zinc selenide or germanium.

8. The reflective visible / thermal infrared separation modulating electrochromic thin film device of claim 1, wherein, The electrolyte layer comprises a solvent, a skeleton polymer and an electrolyte; the solvent is one or more of propylene carbonate, fluorinated ethylene carbonate, ethyl acetate and acetonitrile, the skeleton polymer is one or more of polymethyl methacrylate, polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride and poly(vinylidene fluoride-co-hexafluoroethylene), and the electrolyte is one or more of ionic liquid, lithium salt, sodium salt and protonic acid.

9. The reflective visible / thermal infrared separation modulating electrochromic thin film device of claim 1, wherein, The packaging film is polypropylene, polytetrafluoroethylene, high-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, polyester, fluorinated calcium, zinc sulfide, germanium or high-aluminum-silicon glass.

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