Temperature control device and method

Abstract

A device is presented comprising at least one functional unit comprising first and second electrodes arranged in a spaced-apart relationship, and a chiral material, having spin-selective electron transport properties, located between and being in contact with inner surfaces of said first and second electrodes. This provides that, upon application of an electrons flux from the first electrode to the second electrode through the chiral material, a spin-polarized current is generated creating a thermal gradient across the chiral material, said thermal gradient effecting increase of temperature of the first electrode and decrease of temperature of the second electrode.

Description

[0001] TEMPERATURE CONTROL DEVICE AND METHOD

[0002] TECHNOLOGICAL FIELD

[0003] The present invention is generally in the field of thermal management, and relates to a temperature control device and method, particularly useful for reducing overheating of various media types.

[0004] BACKGROUND ART

[0005] References considered to be relevant as background to the presently disclosed subject matter are listed below:

[0006] 1. Ziabari, M. Zebarjadi, D. Vashaee, A.Shakouri, Nanoscale solid-state cooling: a review, Rep. Prog. Phys. 79, 095901 (2016). DOI 10.1088 / 0034-4885 / 79 / 9 / 095901

[0007] 2. E. Norouzi, C. Park, G. Hwang, Nanoscale heat pipe using surface-diffusion- driven condensate return, Int. J. Heat and Mass Transfer, 130, 1238-1248, (2019). https: / / doi.Org / 10.1016 / j.ijheatmasstransfer.2018.l l.021.

[0008] 3. J. Bruggemann, S. Weiss, P. Nalbach, M. Thorwart,. Exploiting the magnetomechanical interaction for cooling magnetic molecular junctions by spin- polarized currents. New Journal of Physics. 18, 023026 (2016). 10.1088 / 1367- 2630 / 18 / 2 / 023026.

[0009] 4. Gschneidner, K. A. Jr, Pecharsky, V. K. & Tsokol, A. O. Recent developments in magnetocaloric materials. Rep. Prog. Phys. 68, 1479-1539 (2005)

[0010] 5. Franco, V. et al. Magnetocaloric effect: from materials research to refrigeration devices. Prog. Mater. Sci. 93, 112-232 (2018).

[0011] 6. Giauque, W. F. & MacDougall, D. P. 1933 Attainment of temperatures below IK by demagnetization of Gd2(SO4)3- 8H2O. Phys. Rev. 43, 768 (1933).

[0012] 7. A comparative assessment on hydrogen production from low- and high- temperature electrolysis, Int. J. Hydrogen Energy, 38, 3523-3536 (2013).

[0013] 8. W. Mtangi, F. Tassinari, K. Vankayala, A. V. Jentzsch, B. Adelizzi, A. R.A. Palmans, C. Fontanesi, E.W. Meijer, R. Naaman, Control of Electrons’ Spin Eliminates Hydrogen Peroxide Formation During Water Splitting, JACS 139, 2794- 2798 (2017).

[0014] 9. B. Bloom, Y. Paltiel, R. Naaman, D. Waldeck, Chiral Induced Spin Selectivity, Chem. Rev. 124, 1950-1991 (2024).

[0015] 10. T. K. Das, F. Tassinari, R. Naaman, J. Fransson, The Temperature-Dependent Chiral-Induced Spin Selectivity Effect: Experiments and Theory. J. Phys. Chem. C, 126, 3257-3264 (2022).

[0016] 11. K. Ohe, H. Shishido, M. Kato, S. Utsumi, H. Matsuura , Y. Togawa, Chirality- Induced Selectivity of Phonon Angular Momenta in Chiral Quartz Crystals, Phys. Rev. Eett. 132, 056302 (2024).

[0017] Acknowledgement of the above references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.

[0018] BACKGROUND

[0019] Controlling temperature, particularly cooling, on micro and sub-micron scales has become a major technological challenge and a limiting factor in developing advanced microelectronics, biomedical applications, and various submicron devices. Current cooling technologies face significant limitations in efficiently removing heat from nanoscale components, which is critical for their reliable operation.

[0020] Conventional cooling technologies include liquid-vapor phase-change-based cooling devices such as heat pipes, which are widely used for cooling electronic devices due to their reliable operation and high heat flux cooling capability. However, when scaling down to nanoscale dimensions, these conventional approaches become inefficient or impractical.

[0021] Thermoelectric cooling technologies based on the Peltier effect represent another approach for controlling temperature without moving parts. In the Peltier effect, a current flowing between two electrodes made of different materials induces a temperature gradient. However, the efficiency of Peltier-based devices is limited by several parameters. The temperature difference between the cold and warm sides should be small, necessitating multi-stage Peltier elements for higher temperature differences. Additionally, efficient Peltier elements require contradictory material properties: low thermal conductivity to preserve the generated heat gradient, while simultaneously having high electrical conductivity. Since both properties are affected by electron mobility, this requirement fundamentally limits the device efficiency.

[0022] The issue is typically addressed by using exotic materials or semiconductor pellets fabricated from N-type and P-type bismuth telluride, and more recently, from organic polymers. Nevertheless, the efficiency of Peltier-based devices remains relatively low, about 10-15% of the ideal Carnot cycle refrigerator, compared with 40-60% achieved by conventional compression-cycle systems

[0023] Another thermal phenomenon used for cooling is the magnetocaloric effect (MCE). Magnetic refrigeration (MR) based on the MCE is considered to be a promising energy-efficient refrigeration technology. It is based on cooling by adiabatic demagnetization, and it was experimentally demonstrated in the early 1930s. The MCE relies on magnetic refrigerant materials with a large magnetic entropy change. Cooling is achieved by inducing magnetization of the material by a large external magnetic field that induces a ferromagnetic phase. The material absorbs heat from the environment and the ordered magnetic phase relaxes to a paramagnetic one or a non-ordered phase. However, this effect requires an alternating large magnetic field and substantial masses of ferromagnetic material to achieve significant cooling.

[0024] For both the thermoelectric effect and the MCE, the efficiency is substantially less than 50% of the maximal possible Carnot heat engine efficiency. Furthermore, the devices often require expensive or exotic materials, limiting their widespread application.

[0025] GENERAL DESCRIPTION

[0026] There is a need in the art for improved cooling techniques that can efficiently control temperature at various scales, particularly at the nanoscale, using inexpensive materials and without the limitations of conventional heating / cooling technologies.

[0027] The present disclosure addresses the aforementioned needs by providing devices and methods that utilize the chiral induced spin selectivity (CISS) effect for performing thermal management of medium interacting with the device of the present disclosure. To this end, the technique of the present disclosure takes advantage of the unique properties of chiral materials to generate spin-polarized currents to controllably create thermal gradients through the device, enabling efficient cooling and / or heating of the respective side of the device.

[0028] In recent years, the chiral induced spin selectivity (CISS) effect has been studied extensively. The CISS effect refers to the phenomenon where electron transmission through chiral systems depends on the electron's spin. This effect has been studied by numerous research groups worldwide and has implications for various applications in spintronics, chemistry, and biology.

[0029] Recent studies have shown that the spin polarization resulting from the CISS effect can be amplified by chiral phonons, and that chiral phonons can induce spin polarization. Heat enhances spin polarization in chiral systems, and transport through these systems utilizes heat energy to reduce resistance and increase current flow through the chiral system.

[0030] The inventors have found that when electrons are passing from a first electrode to the second (while under certain potential difference between the electrodes) with a chiral material / system located between the electrodes, the spin polarized current is created in the chiral material and produces a temperature gradient along the electron flow, causing the first electrode to become hotter and the second electrode colder. The first electrode becomes hot as electrons leaving it align the spin and the second electrode becomes cold when the electrons lose their alignment.

[0031] In this connection, it should be understood that for electrons flow between such pair of first and second electrodes under potential difference between them, the first electrode from which electrons are ejected functions as a source electrode and the second electrode functions as a drain electrode, while for electric current between the first and second electrodes under the potential difference of the same sign, the electrodes function oppositely. The technique of the present disclosure can generally be implemented with any spin carrying charged particles. Therefore the terms “source electrode” and “drain electrode” should be interpreted broadly, namely, the electrode from which spin carrying charged particles are ejected is termed “source electrode”, and the other electrode, functioning as a destination electrode, is termed “drain electrode”. In the description below and in claims, electrons constitute spin carrying charged particles. Thus, when electrons are passing between the first and second electrode separated by the chiral material / system located between them, by exposing the drain electrode to interaction with a region of a medium, whose overheating is to be reduced, the drain electrode, while becoming cooled, absorbs heat from said medium. Similarly, when heating of a medium is needed, this is achieved at the source side.

[0032] Such arrangement of paired electrodes with the chiral material / system between them can be as small as needed, thus allowing its use for local cooling / heating in micro and sub-micron scales regions.

[0033] It should be noted that the technique of the present disclosure can be used for cooling a certain active device which, when operating, generates heat. In such case, the device of the present disclosure can be accommodated such that the drain electrode is in contact (physical contact) of said active device. In some other embodiments, the case may be such that an element of the active device to be cooled is an electrically conductive element. In this case, this electrically conductive element can serve as the drain electrode of the device of the present disclosure. Hence, the device of the present disclosure can be integral with the active device by adding thereto a source electrode with chiral material coating on its side facing the drain electrode.

[0034] Generally, the technique of the present disclosure can advantageously be used for affecting a temperature change of any type of medium, i.e., gas medium, liquid medium and solid medium. In the description below, just in order to simplify explanation, the term "substance" is used in relation to solid-medium element.

[0035] Thus, according to one aspect of the present disclosure, it provides a device comprising at least one functional unit, the functional unit comprising: first and second electrodes arranged in a spaced-apart relationship; and a chiral material located between and being in contact with inner surfaces of said first and second electrodes, said chiral material having spin- selective electron transport properties; thereby providing that, upon application of a flux of spin-carrying charged particles from the first to the second electrode through the chiral material, a spin-polarized current is generated creating a thermal gradient across the chiral material, said thermal gradient effecting increase of temperature of the first electrode and decrease of temperature of the second electrode.

[0036] More specifically, the technique of the present disclosure utilizes electrons as spin-carrying charged particles, and is therefore described below using this terminology, which however, as noted above, should be interpreted broadly.

[0037] In some embodiments, the functional unit is configured and operable to control the temperature of interaction regions of media with which the electrodes at their outer surfaces are in contact, such that the decrease of temperature of the second electrode affects cooling of the interaction region of the second electrode and the increase of temperature of the first electrode warms the interaction region of the first electrode.

[0038] The chiral material suitable to be used in the technique of the present disclosure comprises at least one of the following: chiral organic molecules, chiral organic polymer, chiral polymer with tunable chiroptical properties that enhance spin selectivity via chiral phonon interactions, chiral inorganic material, chiral self-assembled structure, helicene- based material, supramolecular helical assembly, chiral perovskite, and biological chiral molecules, biological material (DNA, peptides, proteins, and / or oligopeptides).

[0039] In some embodiments, the device includes an array of at least two of the functional units arranged in a spaced-apart relationship, thereby providing a corresponding array of interaction regions associated with one of the first and second electrodes. The different functional units of said array of the functional units may include the same or different configurations of the chiral material.

[0040] The first and second electrodes of the functional unit(s) may be configured in spaced-apart vertical arrangement and / or spaced-apart lateral arrangement and / or spaced- apart radial arrangement.

[0041] One of the first and second electrodes of the functional unit may include a material selected to be in electron energy level alignment with the chiral material between the first and second electrodes to thereby optimize temperature change efficiency of the respective electrode.

[0042] In some embodiments, the device further comprises a temperature controller configured and operable to regulate temperature of at least one of the first and second electrodes of the functional unit. In some embodiments, the first and second electrodes are made of ferromagnetic materials, said spin polarized current inducing magnetization.

[0043] In some embodiments, the second electrode is an element of an active heat generating device. For example, the second electrode of the functional unit is configured as an interface in an electrical junction. The spin polarized current creates the thermal gradient, such that the first electrode increases its temperature while the electrical junction decreases its temperature.

[0044] The present disclosure also provides a system comprising the above-described device and a heat producing device, wherein the second electrode (of the functional unit in the above-described device) at its external surface is in contact with the heat producing device. This provides that the second electrode can controllably absorb heat generated by the heat producing device.

[0045] The present disclosure also provides a device comprising a substance carrying the above-described device, in which the second electrode of the functional unit is exposed to interaction with medium of surroundings of said substance, thereby causing said second electrode to absorb heat from the surroundings of said substance to thereby improve performance of the substance.

[0046] Such substance may comprise at least one of the following: an electronic component, an integrated circuit, a semiconductor device, a battery, an electrode in an electrochemical cell, or a biological system.

[0047] In yet another broad aspect of the present disclosure, it provides a temperature control method comprising: providing a chiral material between at least one pair of spaced-apart first and second electrodes, said chiral material having spin-selective electron transport properties, wherein said chiral material is in physical contact with inner facing surfaces of said first and second electrodes; and applying an electric current between the first and second electrodes through the chiral material to generate a spin-polarized current, thereby creating a thermal gradient via the spin-polarized current causing heat absorbance at one of the first and second electrodes, thereby cooling said electrode. In some embodiments, the heat absorbing electrode is exposed to thermal contact with an interaction region of a medium.

[0048] In some embodiments, an array of at least two of said pairs of the first and second electrodes are provided, such that the second electrodes of the at least two pairs are exposed to thermal contact with at least two respective interaction regions.

[0049] The medium may be constituted by a substance in physical contact with the second electrode.

[0050] Such substance may comprise at least one of the following: an electronic component, an integrated circuit, a semiconductor device, a battery, an electrode in an electrochemical cell, or a biological system.

[0051] In some embodiments, the second electrode is exposed to the medium of surroundings.

[0052] The chiral material can be selected based on its chiroptical activity to enhance spin polarization.

[0053] The method may further comprise controlling temperature of the first electrode to optimize cooling efficiency at the second electrode.

[0054] The interaction region of the medium may comprise a material exhibiting magnetocaloric properties, in which case the spin-polarized current induces magnetization of said material.

[0055] The present disclosure also provides a method of manufacturing the abovedescribed device, according to which the manufacturing of the functional unit includes: forming the first electrode on a substrate; depositing or assembling a chiral material in contact with the first electrode; and forming the second electrode in contact with the chiral material; wherein an arrangement of the first electrode, the chiral material, and the second electrode is configured to create a thermal gradient upon application of an electric current between the electrodes through said chiral material.

[0056] The technique of the present disclosure provides several advantages over conventional cooling (or heating) technologies. Due to the spin-dependent current, the ohmic resistance of the chiral material is reduced while enabling low heat conduction. The reduction of resistance results from the coupling of the electron's spin with its linear momentum, which reduces backscattering. This property eliminates the need for exotic materials and increases efficiency compared to conventional thermoelectric devices.

[0057] Additionally, in contrast to the magnetocaloric effect, the cooling / heating effect of the present disclosure is based on spin currents rather than magnetization. Thus, no magnetic components are required, and there are no moving parts. Based on the unique combination of electro- and magneto -thermal effects, the efficiency of the temperature change effect of the devices of the present disclosure is expected to be very high.

[0058] Furthermore, the device of the present disclosure can be configured with a wide range of dimension scales, from nanoscale to macroscopic scale, and are cost-efficient due to the inexpensive materials required.

[0059] It should also be noted that the technique of the present invention can advantageously be used in electrochemistry since it provides heat conversion to spin polarized current. The ability to widely use renewable energies depends on developing methods to store the produced energy in an efficient way. For a long time, hydrogen has been considered as an important way for storing energy and hence its efficient production remains in focus of research and development methods. A possible approach for efficient hydrogen production are the electrochemical methods by which electricity is used in combination with catalysts and / or light to “split” water into hydrogen and oxygen. It is well established that upon heating the water in the electrolyzer from room temperature to about 80 °C, the overpotential in the reaction is reduced by about 250 mV.

[0060] In the oxygen evolution reaction hydrogen and oxygen are formed from water. This reaction is considered to be spin forbidden, since the oxygen is formed in its triplet ground state while all other reactants and products are in their singlet electronic state. It was established that the reaction can be enhanced if the cathode, on which the oxygen is formed, is coated with a chiral film. This was explained by the spin selective electron transfer to the cathode that also eliminates the production of the byproduct hydrogen peroxide. The spin selectivity is a result of the chiral induced spin selectivity (CISS) effect. In recent studies it has been found that the spin polarization resulting from the CISS effect can be amplified by chiral phonons and chiral phonons can induce spin polarization. The heat enhances spin polarization in the chiral system. Transport through these systems utilizes the heat energy to further reduce resistance and increase the total current passing through the chiral system. This means that for the same operation voltage in chiral systems, heating the system will enhance the hydrogen production beyond the standard improvement that is expected for standard oxygen evolution reactions. In other words, in chiral systems, when heated, the chiral vibrations / phonons, couple better the linear momentum of the electrons and their spin and therefore reduce the efficiency of spin randomization and back scattering of the electrons.

[0061] Waste heat at low temperatures is difficult to utilize as an energy source. For example, warm water is the byproduct of electrical powerplants and are also available from geo-sources. Typically, this relatively low temperature water (between 40 to 70 C) is difficult to use as energy source. This thermal energy could be utilized directly and efficiently for storing energy by the technique of the present disclosure. It

[0062] It is important to note that in many cases cooling should be very local. In order to reduce the cooling power in integrated circuits one wants to cool only the hot spots. The technique of the present disclosure utilizes a local current, therefore the cooling can be controlled and achieved with nanometric resolution.

[0063] BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

[0065] Fig. 1A illustrates schematically a device of the present disclosure comprising a functional unit configured according to the present disclosure for affecting temperature changes at opposite sides of the functional unit;

[0066] Fig. IB shows various examples of the arrangement of the elements of the functional unit;

[0067] Fig. 1C exemplifies a device of the present disclosure including an array of the functional units;

[0068] Figs. ID and IE illustrate the mechanism underlying the operational principles of the device of the present disclosure; Figs. 2A to 2D illustrate different types of chiral materials suitable for use in the device of the present disclosure, wherein Fig. 2A shows a molecular structure corresponding to topological molecular knot; Figs. 2B to 2D show examples of weakly self-assembled helicenes;

[0069] Figs. 3A and 3B illustrate two examples, respectively, of a device / system utilizing the device of the present disclosure; and

[0070] Figs. 4A to 4D illustrate experimental results, showing configuration and operation of the exemplary devices of the present disclosure.

[0071] DETAILED DESCRIPTION OF EMBODIMENTS

[0072] Before the present disclosure is described in detail, it is to be understood that unless otherwise indicated, this disclosure is not limited to specific materials, chiral structures, or electronic configurations. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present disclosure.

[0073] As used herein, the term "chiral material" or "chiral system" refers to any material that lacks an internal plane of symmetry and has a non-superimposable mirror image. As a result, chiral material exhibits Chiral-Induced Spin Selectivity (CISS), which is the phenomenon where electron transmission through chiral systems depends on the electron's spin.

[0074] The present disclosure is based on the inventors' understanding that when passing electric current (typically electron flux) from source electrode to drain electrode via a chiral material between the electrodes, the spin current produces a temperature gradient such that the source becomes hotter and the drain colder. This effect can be viewed as the inverse of the chiral-phonon-activated spin Seebeck effect, in which a spin current is induced in a chiral material due to a temperature gradient between its two ends.

[0075] Although the technique of the present disclosure can be used for inducing both heating and cooling effects at opposite sides of the functional unit when operated, in the disclosure herein, the term "CISSCO" is used referring to Chiral-Induced Spin Selectivity Cooling effect of the present disclosure, which is the effect whereby a spin-polarized current flowing through a chiral material enclosed between two electrodes creates a thermal gradient causing cooling of one electrode (operable as a drain electrode) and heating of the other electrode (operable as a source electrode). It should, however, be understood that the vice versa effect is created at the source electrode side.

[0076] Therefore, the term "CISSCO effect" or "CISSCO-based effect / device" as used at times herein below, should be interpreted broader covering also the heating effect occurring at the side of the source-type electrode.

[0077] In the CISSCO effect, a spin-polarized current flows through the chiral system / material. Due to the coupling between the angular momentum of the electrons (their spin) and the linear momentum, the backscattering within the chiral system is reduced, since any backscattering event requires changing of the spin. Hence, the ohmic heating per transferred electron is reduced by a factor of two or more. Moreover, in CISSCO, the spin information can pass via super-exchange interactions like in spintronics, reducing the loss to phonons while passing the information. In that sense, similar to the planar Hall effect, the spin degree of freedom is decoupled from the current, providing a thermodynamic advantage over the Peltier effect.

[0078] Referring to Fig. 1A, a schematic illustration of a device 12 of the present disclosure is shown. The device includes at least one functional unit - single such functional unit 10 being exemplified in the figure. The functional unit 10 includes a first electrode El, a second electrode E2, and a chiral material / system (layer) CM having spin- selective electron transport properties located between the electrodes. The chiral material is in contact with inner surfaces S’in and S2in of the electrodes El and E2 (i.e., surface of the electrodes by which they face each other). When electric current (electrons' flux) flow from the first electrode El (operable as a source electrode) to the second electrode E2 (operable as a drain electrode), the first electrode becomes heated while the temperature of the second electrode decreases (it cools).

[0079] It should be noted that the first and second electrodes of the functional unit may be configured in a spaced-apart vertical arrangement, or a spaced-apart lateral arrangement, or a spaced-apart radial arrangement. This is exemplified in Fig. IB.

[0080] As also shown in Fig. 1A, the functional unit can be equipped and controllably operated by an electric power supply circuit 14, which (although not specifically shown) is controllably operated to regulate the electric current through the functional unit 10. It should be noted that a temperature controller 16 can be provided, being configured and operable to regulate the temperature of at least one of the first and second electrodes of the functional unit 10. This temperature control may assist in optimizing the cooling efficiency by maintaining appropriate temperature gradients.

[0081] The functional unit can thus be configured and operable to control the temperature of an interaction region IR of a medium (Medium l)cooi with which the second electrode E2 at its outer surface S20ut is in contact and which is to be cooled. Hence, the decrease of temperature of the second electrode E2 effects cooling of said interaction region IR. Alternatively or additionally, the functional unit can be configured and operable to control the temperature of an interaction region IR of a medium (Medium2)heat with which the first electrode El (source) at its outer surface S’out is in contact and which is to be heated.

[0082] In the description below, the technique of the present disclosure is described as being used to induce a cooling effect. However it should be understood that the present disclosure is not limited to the cooling effect and can be similarly used to alternatively or additionally utilize the heating occurring at the source side of the functional unit.

[0083] It should be noted that the surrounding heat generating medium (heat source) may include at least one of waste heat from an electronic device, geothermal energy, and heat generated by an electrochemical reaction.

[0084] In some embodiments, the medium in which a temperature change is to be affected (e.g., the temperature is to be reduced) by interaction with the electrode of the functional unit may be a substance (a physical element) with which the second electrode is in physical contact. Such substance may be an electronic component, an integrated circuit, a semiconductor device, a battery, an electrode in an electrochemical cell, or a biological system. The substance may be configured for attachment to the electrode, or may be integral with the functional unit. This will be exemplified further below.

[0085] In some other embodiments, the functional unit is used to reduce (generally affect the temperature change) the temperature of the surroundings, i.e., gas and / or liquid medium. The functional unit is thus arranged such that the drain electrode is exposed to the medium of surroundings to induce cooling effect therein, or the source electrode is exposed to the medium to induce heating effect therein. The device 12 of the present disclosure can include an array of N (at least two) functional units 10, as exemplified in Fig. 1C. Although not specifically shown in the figure, the functional units can be independently operable by the power supply circuits and possibly also temperature controllers. Further, different functional units of the array may include the same or different configurations of the chiral material, as well as may include similar or different relative accommodation of the paired electrodes. As shown in the figure, the functional units of the array are arranged in a spaced-apart relationship, thereby providing a corresponding array of interaction regions IR1, IR2, . . . IRn.

[0086] Reference is made to Figs. ID and IE illustrating more specifically the mechanism underlying the principles of the present disclosure implemented in the CISSCO-based functional unit 10 of the present disclosure. As shown, the functional unit 10 includes first and second electrodes El and E2 (being operable as source and drain electrodes in the operational scheme shown in the figure), and chiral material / system CM between them.

[0087] Fig. ID shows an electron current flowing from the source to the drain through the chiral system. Due to the CISS effect described above, the current is formed of electrons with mostly one spin direction. Fig IE shows the energy splitting in the chiral material due to spin polarization of the electrons. When electrons leave states below the Fermi level, the filling of the empty states involves heating of the source electrode due to energy release in the source. When the electrons enter the drain, they have to enter empty states above the Fermi level, and this requires transferring phonons' energy to electronic energy, hence cooling of the drain.

[0088] The energy level alignment between the electrodes and the chiral material is appropriately adjusted to define the cooling efficiency. To this end, one of the first and second electrodes of the functional unit may include a material selected, e.g., semiconductors in which either the valence band edge or the conduction band edge (for holes or electrons transfer, respectively) are aligned with electron energy levels of the chiral material located between the electrodes, to thereby optimize the cooling efficiency of the second (drain) electrode.

[0089] The CISSCO effect has several advantages over conventional thermoelectric and thermomagnetic effects. Due to the spin-dependent current, the ohmic resistance of the chiral system is reduced while enabling low heat conduction. The reduction of the resistance results from the coupling of the electron's spin with its linear momentum, which reduces backscattering. This property eliminates the need for exotic materials and increases efficiency compared to conventional thermoelectric devices. In contrast to the thermomagnetic effect, the CISSCO effect is based on spin currents rather than magnetization. Thus, no magnetic components are required, and there are no moving parts. Based on the unique combination of the electro- and magneto-thermal effects in CISSCO, the efficiency of the CISSCO effect is expected to be very high. The CISSCO devices can be made on a wide range of length scales, from nanoscale to macroscopic scale, and are cost-efficient due to the inexpensive materials required.

[0090] The chiral material suitable to be used in the functional unit of the present disclosure, i.e., chiral material having spin- selective electron transport properties, may include at least one of the following: chiral organic molecules, chiral organic polymers, chiral inorganic materials, chiral self-assembled structures, helicene-based materials, supramolecular helical assemblies, chiral perovskites, and biological chiral molecules.

[0091] Figs. 2A to 2D illustrate different types of chiral material suitable for use in the functional unit of the present disclosure. Fig. 2A shows a molecular structure corresponding to topological molecular knot. In the chiral molecular trefoil knot, there are no stereogenic carbon atoms, and chirality results from the spatial arrangements of crossings in the trefoil knot structures. The molecules show a very high spin polarization of nearly 90%. Figs. 2B to 2D show examples of weakly self-assembled helicenes. Helicenes are ortho-fused aromatic compounds with helical chirality. Fig 2B shows examples of two [6]helicenes (compounds 1 and 2), 2,15- and 4,13-disubstituted [6]helicenes, respectively, substituted in their periphery with two 3,4,5-tris(dodecyloxy)- N-(4-ethynylphenyl)benzamide moieties. The [6]helicene 1 self-assembles in a head-to- tail manner (Fig. 2C) to form aggregated species, whereas [6] helicene 2 self-assembles in a head-to-head fashion (Fig. 2D). Both [6]helicenes 1 and 2 show CISS effects, with spin selectivity during electron transport through a chiral layer of the helicene-based polymer.

[0092] In some embodiments, the chiral material includes a material with temperature- enhanced spin selectivity, for example, polypeptides and oligopeptides that have strong temperature dependence around room temperature. Phonons play a key role in the CISS effect. Temperature-dependent spin selectivity measurements on chiral polymers can provide insight into the role of temperature on the spin polarization generated via the CISS effect and the optimal operation temperature for CISSCO devices.

[0093] In some embodiments, the chiral material includes at least one chiral polymer with tunable chiroptical properties that enhance spin selectivity via chiral phonon interactions. The CISS effect is known to increase with the chiroptical activity of the organic spin filter. Different types of chiralities (central, axial, helical) and different types of polymers (supramolecular, covalent) can be used to tune the chiroptical properties. An example of a chiral material exhibiting chiroptical properties are the [6]helicenes 1 and 2 described above.

[0094] The CISSCO-based functional unit of given dimensions, due to the spin- selective nature of electron transport through the chiral material, can provide cooling efficiency higher than that of a Peltier cooling device of similar dimensions. The improvement depends on the exact conditions and temperature, and the efficiency of the CISSCO-based functional unit of given dimensions can be 2- 10 times higher than that of the Peltier effect in a cooling device of similar dimensions.

[0095] It should be noted that the chiral material may be selected to have relatively low thermal conductivity, while maintaining high spin- selective electrical conductivity. This combination of properties is advantageous for efficient cooling, as it allows for maintaining the thermal gradient while facilitating efficient electron transport.

[0096] In some embodiments, the chiral material includes a biological material selected from DNA, peptides, proteins, and oligopeptides. These biological materials naturally possess chiral structures and can exhibit the CISS effect, making them suitable for use in CISSCO devices.

[0097] As mentioned above, the medium in which a temperature change is to be affected by interaction with the electrode of the functional unit may be a substance (physical element) with which the electrode of the functional unit is in physical contact, thus enabling controllable temperature change (typically cooling) of said substance. Such substance may be an electronic component, an integrated circuit, a semiconductor device, a battery, an electrode in an electrochemical cell, or a biological system. The substance may be configured for attachment to the electrode, or may be integral with the functional unit. This will be exemplified further below. This is exemplified in Fig. 3A.

[0098] Fig. 3A illustrates schematically a system 20 in which the device 12 of the present disclosure (only its functional unit 10 being shown in the figure) is associated with an active device 22 constituting the substance whose temperature is to be controllably managed (e.g., decreased to avoid overheating of the substance). The functional unit 10 may be attachable to the active device 22 or may be integral with such active device 22. For example, the active device 22 is of the type which during its operation presents a heat producing device. Typical examples of such active device include: an electronic component, an integrated circuit, a semiconductor device, a battery, an electrode in an electrochemical cell, etc. By providing a contact between the outer surface of the drain electrode of the functional unit and the active device 22, and properly operating the functional unit 10 as described above, the temperature of the drain electrode is decreased, and the drain electrode absorbs heat produced by the active device 22.

[0099] It should be noted, and also exemplified in Fig. 3B, that the functional unit can be integral with the active device 20 such that the source or drain electrode El or E2 (depending on the temperature change effect to be achieved) of the functional unit is constituted by an electrically conductive element 22a of the active device. In other words, the respective electrode (e.g., drain electrode of the functional unit) is arranged as an interface in an electrical junction defined by the active device. For example, the chiral cooling layer may be part of the connecting wire to the memory units which can work at very high frequency and produce high local heat . This configuration can be particularly useful for cooling electrical junctions, which are often hotspots in electronic devices.

[0100] Turning back to Fig. 1A, it should be noted that the first and second electrodes can be made of ferromagnetic materials. In this case, the spin-polarized current induces magnetization. In such configuration, the temperature change effect is combined with magnetic properties, potentially enhancing the cooling / heating effect or enabling additional functionalities.

[0101] Reference is made to Figs. 4A-4D showing experimental results obtained by the inventors. Fig. 4A shows a cross-sectional view of the assembled device of the present disclosure utilizing the functional unit 10 with a vertical configuration of the electrodes and chiral material between them. In Fig. 4B a similar device is constructed on a 10x10 mm Si / Si O2 substrate, where a ~50 nm Au / Ni bottom contact is first deposited, followed by the deposition of a chiral middle layer and finally, a ~50 nm Au top contact is applied. In this example, 30nm S-PANI (polyalanine with a sulphonic acid end group) chiral polymer is used between the electrodes.

[0102] The inventors have manufactured several such devices with different thicknesses of the chiral layer. The inventors conducted specific heat measurements performed as a function of temperature. The measurements were performed using pulsed current for heating and measuring of the resistive decay rate. For each thickness, chiral, non-chiral and racemic based devices were compared. As shown in Figs. 4A and 4B, a very thin semitransparent Au layer may be used as a top contact (Fig. 4B) or this can be replaced by ITO contact (Fig. 4A).

[0103] For cooling efficiency measurements, an AC current was applied from the top contact to the bottom contact through the chiral middle layer. To measure the temperatures at the bottom and top contacts, two methods were used. The first method involves monitoring the change in resistance of the Au layers as a function of temperature, while the second method utilizes a negative temperature coefficient (NTC) thermocouple, which is coupled to the Au layers, to directly measure the temperature change.

[0104] Fig. 4C illustrates experimental results obtained from a vertical CISSCO device, in the form of the temperature change AT as a function of the electric current through the device. The electric current was applied in a pulsed mode (as exemplified in Fig. 4D).

[0105] As can be seen at 500mA electric current, the temperature difference AT=80°C is achieved between the Au and Cu electrodes.

[0106] The present disclosure also provides a method of manufacturing the device described above. The method includes manufacturing the functional unit by forming the first electrode on a substrate, depositing or assembling a chiral material in contact with the first electrode, and forming the second electrode in contact with the chiral material. For the purposes of some applications, one of the electrodes is configured to contact with an interaction region of a specific substance. The manufacturing method can be adapted for different configurations of the device, including vertical, lateral, and radial arrangements of the electrodes. Different chiral materials can be used depending on the specific application and desired cooling performance.

[0107] While the disclosure has been described with reference to specific embodiments, these descriptions are merely illustrative and are not intended to be limiting. Various modifications and applications may occur to those skilled in the art without departing from the true spirit and scope of the disclosure as defined by the appended claims.

Claims

CLAIMS:

1. A device comprising at least one functional unit, the functional unit comprising: first and second electrodes arranged in a spaced-apart relationship; and a chiral material located between and being in contact with inner surfaces of said first and second electrodes, said chiral material having spin- selective electron transport properties; thereby providing that, upon application of a flux of spin-carrying charged particles from the first electrode to the second electrode through the chiral material, a spin-polarized current is generated creating a thermal gradient across the chiral material, said thermal gradient effecting increase of temperature of the first electrode and decrease of temperature of the second electrode.

2. The device according to claim 1, wherein the spin-carrying charged particles are electrons.

3. The device according to claim 1 or 2, wherein the functional unit is configured and operable to control the temperature of interaction regions of media with which said electrodes at their outer surfaces are in contact, such that said decrease of temperature of the second electrode affects cooling of the interaction region of the second electrode and said increase of temperature of the first electrode warms the interaction region of the first electrode.

4. The device according to any one of the preceding claims, wherein the chiral material comprises at least one of the following: chiral organic molecules, chiral organic polymer, chiral inorganic material, chiral self-assembled structure, helicene-based material, supramolecular helical assembly, chiral perovskite, and biological chiral molecules.

5. The device according to any one of the preceding claims, wherein the chiral material comprises a material with temperature-enhanced spin selectivity.

6. The device according to any one of claims 3 to 5, comprising an array of at least two of the functional units arranged in a spaced-apart relationship, thereby providing a corresponding array of interaction regions associated with one of the first and second electrodes.

7. The device according to claim 6, wherein different functional units of said array of the functional units comprise the same or different configurations of the chiral material.

8. The device according to any one of the preceding claims, wherein the first and second electrodes of the functional unit are configured in at least one of: a spaced-apart vertical arrangement, a spaced-apart lateral arrangement, or a spaced-apart radial arrangement.

9. The device according to any one of the preceding claims, wherein the chiral material comprises at least one chiral polymer with tunable chiroptical properties that enhance spin selectivity via chiral phonon interactions.

10. The device according to any one of claims 2 to 9, wherein one of the first and second electrodes of the functional unit comprises a material selected to be in electron energy level alignment with the chiral material between the first and second electrodes to thereby optimize temperature change efficiency of the respective electrode.

11. The device according to any one of the preceding claims, further comprising a temperature controller configured and operable to regulate temperature of at least one of the first and second electrodes of the functional unit.

12. The device according to any one of the preceding claims, wherein the chiral material comprises a biological material selected from the following: DNA, peptides, proteins, and oligopeptides.

13. The device according to any one of claims 2 to 12, wherein said first and second electrodes are made of ferromagnetic materials, said spin polarized current inducing magnetization.

14. The device according to any one of the preceding claims, wherein said second electrode is an element of an active heat generating device.

15. The device according to any one of claims 2 to 14, wherein the second electrode of the functional unit is configured as an interface in an electrical junction, said spin polarized current creating the thermal gradient, such that the first electrode increases its temperature while the electrical junction decreases its temperature.

16. A system comprising: a heat producing device and the device of any one of the preceding claims 1 to 13, wherein the second electrode at its external surface is in contactwith said heat producing device providing that said second electrode controllably absorbs heat generated by the heat producing device.

17. A device comprising a substance carrying the device of any one of claims 1 to 13, in which the second electrode of the functional unit is exposed to interaction with medium of surroundings of said substance, thereby causing said second electrode to absorb heat from the surroundings of said substance to thereby improve performance of the substance.

18. The device according to claim 17, wherein the spin-carrying charged particles are electrons, said substance comprising at least one of the following: an electronic component, an integrated circuit, a semiconductor device, a battery, an electrode in an electrochemical cell, or a biological system.

19. A temperature control method comprising: providing a chiral material between at least one pair of spaced-apart first and second electrodes, said chiral material having spin-selective electron transport properties, wherein said chiral material is in physical contact with inner facing surfaces of said first and second electrodes ; applying an electric current between the first and second electrodes through the chiral material to generate a spin-polarized current, thereby creating a thermal gradient via the spin-polarized current causing heat absorbance at one of the first and second electrodes, thereby cooling said electrode.

20. The method according to claim 19, comprising exposing said heat absorbing electrode to thermal contact with an interaction region of a medium.

21. The method according to claim 19, wherein an array of at least two of said pairs of the first and second electrodes are provided, such that the second electrodes of the at least two pairs are exposed to thermal contact with at least two respective interaction regions.

22. The method according to claim 19 or 20, wherein said medium is a substance in physical contact with the second electrode.

23. The method according to claim 22, wherein said substance comprises at least one of the following: an electronic component, an integrated circuit, a semiconductor device, a battery, an electrode in an electrochemical cell, or a biological system.

24. The method according to claim 19 or 20, wherein said second electrode is exposed to the medium of surroundings.

25. The method according to any one of claims 19 to 24, wherein the chiral material is selected based on its chiroptical activity to enhance spin polarization.

26. The method according to any one of claims 19 to 25, further comprising controlling a temperature of the first electrode to optimize cooling efficiency at the second electrode.

27. The method according to any one of claims 19 to 26, wherein said interaction region of the medium comprises a material exhibiting magnetocaloric properties, the spin- polarized current inducing magnetization of said material.

28. A method of manufacturing the device according to any one of claims 1 to 13, the method comprising manufacturing the functional unit by carrying out the following: forming the first electrode on a substrate; depositing or assembling a chiral material in contact with the first electrode; and forming the second electrode in contact with the chiral material; wherein an arrangement of the first electrode, the chiral material, and the second electrode is configured to create a thermal gradient upon application of an electric current between the electrodes through said chiral material.

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