Static Permittivity Research Articles

Dynamic permittivity of confined water under a static background field.

Molecular and collective reorientations in interfacial water are by-and-large decelerated near surfaces subjected to outgoing electric fields (pointing from surface to liquid, i.e., when the surface carries positive charge). In incoming fields at negatively charged surfaces, these rates show a nonmonotonic dependence on field strength where fastest reorientations are observed when the field alignment barely offsets the polarizing effects due to interfacial hydrogen bonding. This extremum coincides with a peak of local static permittivity. We use molecular dynamics simulations to explore the impact of background static field on high frequency AC permittivity in hydration water under an electric field mimicking the conditions inside a capacitor where one of the confinement walls is subject to an outgoing field and the other one to an incoming field. At strong static fields, the absorption peak undergoes a monotonic blue shift upon increasing field strength in both hydration layers. At intermediate fields, however, the hydration region at the wall under an incoming field (the negative capacitor plate) features a red shift coinciding with maximal static-permittivity and reorientation-rate. The shift is mostly determined by the variation of the inverse static dielectric constant as proposed for mono-exponentially decaying polarization correlations. Conversely, hydration water at the opposite (positively charged) surface features a monotonic blue shift consistent with conventional saturation. The sensitivity of absorption peaks on the field suggests that surface charge densities could be deduced from sub-THz dielectric spectroscopy experiments in porous materials when interfaces accommodate a major fraction of water contained in the system.

Synthesis of new liquid crystal Schiff's bases bearing ester moiety, DFT calculation and mesomorphic studies

A new homologues series of liquid crystalline material (E)-4-(((3,4-dimethylphenyl) imino) methyl) phenyl4-n-alkoxybenzoate (SBn) synthesized. SBn compounds was subjected to analysis using infrared spectroscopy, proton magnetic resonance, 13C NMR, UV- visible and mass spectroscopy for characterization. The investigation of liquid crystalline phases and their transition enthalpies was carried out using a polarized optical microscope and differential scanning calorimetry, respectively. All compounds within the homologous series display mesogenic properties. The SB1 -SB7 homologues exhibit an enantiotropic nematic mesophase within the temperature range of 180–106 °C, while the SB14 -SB18 homologues show a smectic A mesophase at temperatures between 78 and 75 °C. Additionally, the SB8 -SB10 homologues exhibit a monotropic smectic A mesophase at 61–59 °C. The phase transitions observed in series SBn are compared with those of structurally related compounds to assess the influence of central linkage and lateral tail `substitution on their mesophase behavior. With the help of DFT; EHOMO and ELUMO energy gap were computed to be negative for all derivative molecules, indicating their stability and in the following order: SB4 > SB6 > SB8 > SB12. Dielectric through determined values of complex permittivity of the synthesised liquid crystal over a broad frequency range are reported. Determined static permittivity value of liquid crystal is 2.25, at room temperature. The compound SBn exhibited a relaxation peak in the dielectric loss spectra in the microwave frequency range, which may be assigned to the rotation of the end polar group of the molecule.

Understanding water behavior through activity coefficients in aqueous solutions: insights from experimental and modeled relative static permittivity

Understanding water behavior through activity coefficients in aqueous solutions: insights from experimental and modeled relative static permittivity

How Molecular Orientation Affects the Static Permittivity Profile of the Polar and Nonpolar Liquid-Liquid Interface.

The dielectric permittivity across the liquid-liquid interface presents an intrinsic response, with respect to the instantaneous interface reference. We hypothesize that dielectric responses across the nonpolar and polar liquid-liquid interfaces have different behaviors and underlying mechanisms. Molecular dynamics simulations were used to compare and contrast the dielectric response of a nonpolar (1,2-dichloroethane/water) and a polar (1-octanol/water) liquid-liquid interface system. We found that the enhanced dielectric permittivity at the nonpolar interface is attributed to the increased water dipole orientation and polarization density. In the case of the polar interface, strong association of the immiscible solvents inhibits the molecular dipole orientation, counteracting the effect from the enhanced surface water polarization density and resulting in a standard dielectric response. Detailed knowledge of the hydrogen bond networks and molecular dipole orientation with respect to the specific instantaneous interfacial and bulk regions reveals the effect of molecular proximity and the interaction with the opposing interfacial molecules on the mechanism of the dielectric permittivity response across the liquid-liquid interface phase boundary.

Effects of hydrostatic pressure on amorphous chiral materials: Impact on homochiral or heterochiral H-bond sequences

High pressure effects on static dielectric permittivity of homochiral and heterochiral N-acetyl-α-methyl-benzylamine (Nac-MBA) were investigated. For homochiral composition, the static permittivity increases of 178% with pressure at T = 388 K. Interestingly, as pressure continued increasing, εS drastically collapsed to reach ε∞=3±0.3. In the case of heterochiral composition, the static permittivity increases with pressure (in the same magnitude order as the pure enantiomer), and reaches a constant value depending on the isothermal temperature. Thus, the size of the H-bond aggregates is highly pressure sensitive, increasing up to a level that crystallization becomes unavoidable. For heterochiral composition, this process may be kinetically time consuming since the initial heterochiral H-bond aggregates need to be surrounded by their suitable neighbors in order to fulfilled the crystalline packing. The initial H-bond sequences are the precursors of the future crystalline arrangement under pressure application.

Anisotropic quasi-static permittivity of rare-earth scandate single crystals measured by terahertz spectroscopy

We report the real-valued static and complex-valued quasi-static anisotropic permittivity parameters of rare-earth scandate orthorhombic single crystal GdScO3 (GSO), TbScO3 (TSO), and DyScO3 (DSO). Employing continuous-wave terahertz spectroscopy (0.2–1 THz), the complex permittivity was extracted using an anisotropic ambient-film-ambient model. Data obtained from multiple samples of the same oxides and different surface cuts were analyzed simultaneously. The zero-frequency limit of the modeled data indicates that at room temperature the real part of the dielectric tensor components for GSO are ɛa = 22.7, ɛb = 19.3, and ɛc = 28.1; for DSO, ɛa = 20.3, ɛb = 17.4, and ɛc = 31.1; and for TSO, ɛa = 21.6, ɛb = 18.1, and ɛc = 30.3, with a, b, and c crystallographic axes constituting the principal directions for the permittivity tensor. These results are in excellent agreement with expectations from theoretical computations and with scarcely available data from previous experimental studies. Furthermore, our results evidence a noticeable attenuation, which increases with frequency, and are very significant especially at the higher frequency end of the measurement and along the c-direction in all samples. We suggest the attenuation is most likely caused by the onset of absorption due to long-wavelength active optical phonon modes. These results are important for electronic and potential sub-terahertz applications (e.g., quarter-wave plate) benefiting from the large index contrast along different directions in these materials.

Suppressed terahertz dynamics of water confined in nanometer gaps.

Nanoconfined waters exhibit low static permittivity mainly due to interfacial effects that span about one nanometer. The characteristic length scale may be much longer in the terahertz (THz) regime where long-range collective dynamics occur; however, the THz dynamics have been largely unexplored because of the lack of a robust platform. Here, we use metallic loop nanogaps to sharply enhance light-matter interactions and precisely measure real and imaginary THz refractive indices of nanoconfined water at gap widths ranging from 2 to 20 nanometers, spanning mostly interfacial waters all the way to quasi-bulk waters. We find that, in addition to the well-known interfacial effect, the confinement effect also contributes substantially to the decrease in the complex refractive indices of the nanoconfined water by cutting off low-energy vibrational modes, even at gap widths as large as 10 nanometers. Our findings provide valuable insights into the collective dynamics of water molecules which is crucial to understanding water-mediated processes.

Electronic and optical properties of doped monolayer MoS2 under shear deformation

The effect of O-atom doping on the electronic and optical properties of monolayer MoS2 under shear deformation has been systematically investigated using first principles. The results show that shear deformation reduces the structural stability of the doped system. The forbidden band width of the doped system decreases sequentially with increasing shear deformation, while conductivity increases. The density of states of both intrinsic and doped systems is primarily contributed by the 4d and 3p orbitals of the Mo and S atoms, respectively. Analysis of the optical properties reveals that shear deformation enhances the static permittivity of the doped systems, leading to an increased ability to bind charges. Additionally, absorption and reflection peaks of all doped systems occur in the ultraviolet region. Compared to the doped system without shear deformation, absorption peaks of the remaining doped systems shift towards the high energy region, resulting in enhanced utilization of ultraviolet light. In the energy range of 16.7–17.3 eV, peak energy loss of all doped systems decreases sequentially, suggesting that shear deformation can reduce energy loss. These results demonstrate that shear deformation can modulate the optoelectronic properties of O-doped monolayer MoS2 and provide a theoretical foundation for practical applications in semiconductor devices.

Electronic structure and optical properties of nitrogen-doped antimonene under biaxial strain: first-principles study.

In this thesis, the role of N atom doping and biaxial strain in modulating the electronic structure and optical properties of antimonene has been deeply investigated using a first-principles approach based on density-functional theory. The results show that N doping significantly reduces the band gap of antimonene and introduces new electronic states, thus affecting its electronic structure. In terms of optical properties, N doping reduces the static permittivity of antimonene and alters its absorption, reflection, and energy loss properties. In addition, biaxial strain further enhanced the modulation effect of these properties. This study not only provides theoretical support for the application of antimonene in the field of high-performance two-dimensional electronic and optoelectronic devices, but also reveals strain and doping as an effective means to modulate the physical properties of two-dimensional materials. For the calculations, we used the DFT-based CASTEP software package for the simulation of the electronic structure. In order to more accurately characterize the weak interactions between two-dimensional materials, we specifically introduced the Van der Waals dispersion correction. We have chosen the Perdew-Burke-Ernzerhof (PBE) exchange-correlation generalization under the generalized gradient approximation (GGA) and combined it with the Van der Waals correction term in order to fully consider the electronic structure of antimonene. For the calculation parameter settings, we set the truncation energy to 400 eV to ensure the accuracy of the calculation. Meanwhile, we adopt a 6 × 6 × 1 k-point grid for Brillouin zone sampling to obtain more accurate energy band structure and density of states information. For the convergence settings, the convergence criteria for both the system energy and the interaction force between atoms were set to 1 × 10-5 eV and 0.01 eV/Å, respectively. We selected a 3 × 3 × 1 supercell model with 18 Sb atoms. A vacuum thickness of 18 Å was established in the Z direction, which is sufficient to avoid interactions between the two atomic layers above and below the periodic structure.

Molecular interaction between thiamine hydrochloride-DMSO binary mixture: a TDR spectroscopic approach

ABSTRACT The dielectric measurements of thiamine hydrochloride (vitamin B1 hydrochloride) and dimethyl sulphoxide (DMSO) binary mixtures have been carried out in the frequency range of 10 MHz to 50 GHz at 25°C, 20°C and 15°C using the TDR technique. The dielectric parameters such as complex dielectric permittivity ɛ*(ω), static dielectric permittivity (ɛs), relaxation time (τ), and asymmetric distribution parameter (β) are obtained by using Cole-Davidson model. These parameters are used to compute thermodynamic properties, Kirkwood correlation factor (geff), and excess molar volume (VE). The heteromolecular H-bonding existing in the binary mixture is explained.

H-bonding interaction study for binary mixtures of methyl cellosolve and ethanol: a dielectric, FTIR spectroscopic and volumetric approach

The dielectric measurement of neat ethylene glycol monomethyl ether (EGMME), neat ethanol and their binary mixtures have been carried out using time domain technique in frequency range of 10 MHz to 50 GHz at the temperature range from 10 °C to 25 °C with a difference of 5 °C. The frequency domain technique within the frequency range of 20 Hz to 2 MHz is used to obtain complex dielectric permittivity ε*(ω), electrical modulus M*(ω), complex electrical conductivity σ*(ω) and loss tangent (tan δ) at 25 °C. The dielectric spectra obtained using TDR technique are fitted in Cole-Davidson model to extract the dielectric parameters such as static dielectric permittivity (ε s), relaxation time (τ) and asymmetric distribution parameter (β). These relaxation parameter values are used to predict intermolecular hydrogen bonding between EGMME and ethanol molecules. Furthermore, the inter-molecular interactions through H-bonding between EGMME and ethanol molecules have been confirmed and discussed using Kirkwood correlation factor, excess permittivity, thermodynamic parameter, Bruggeman factor, excess molar volume, excess dielectric permittivity at high frequency and Fourier transform infrared (FTIR) spectra.

Estimation of Ionic Impurities in Poly(propylene Glycol) Diacrylate Monomers/Liquid Crystal E7 Mixtures Using Dielectric Spectroscopy

The study investigated the effect of the molecular weight of three difunctional poly(propylene glycol) diacrylates on the temperature-dependent ionic conductivity of these monomers and their blends with an eutectic nematic liquid crystal mixture (E7). The results revealed two distinct regions. At low temperatures, ionic conduction can be described by the Vogel–Tamman–Fulcher (VTF) equation, while at high temperatures, the conductivity data follow the prediction of the Arrhenius model. The Arrhenius and VTF parameters and their corresponding activation energies were determined using the least squares method. In addition, a conductivity analysis based on an ionic hopping model is proposed. Estimates of ion concentrations and diffusion constants were calculated. It was found that both the ionic concentration and the diffusion constant decrease with the increase in the molecular weight of the monomers. The static dielectric permittivity decreases in the following order: TPGDA, PPGDA540, and PPGDA900. This can be explained by the higher dipole moment of TPGDA, which is caused by an enhanced volume density of carbonyl groups.

The structural, stability, electronic, optical and thermodynamic properties of MoX2 (X= S, Se, and Te) under hydrostatic pressures: a plasmon approach and first-principle study.

The new equations have been developed for the structural and electronic properties using the plasmon calculations for the first time for 2-D MoX2 structures. Literature shows still an extensive study is required on the stability and optical properties of MoX2 under different hydrostatic pressures and thermal properties under different temperatures using the first principles, for electronic industrial applications. The stability is analyzed using binding energy and phonon calculations. The phase transition of metallization of MoX2 is discussed using band structure calculations under different hydrostatic pressures. The calculated work function shows the photoemission starts from the threshold frequency of 4.189×104 cm-1, 3.184×104 cm-1, and 3.651×104 cm-1, respectively, for MoS2, MoSe2, and MoTe2 materials. The optical properties such as refractive index n(0), and static dielectric permittivity ε(0) for three successive materials are calculated under different hydrostatic pressures, applicable for optoelectronic applications. The calculated theoretical and computational values agree well with each other and also agree with reported and experimental values. Some of the values are calculated for the first time. The theoretical equations are derived using the molecular weight, effective valence electrons, and density of molecule of MoX2 structures. The simulation work is performed using GGA-PBE approximation in the CASTEP simulation package with DFT+D semi-empirical dispersion correction. An ultra-soft pseudopotential representation calculates the electronic and optical properties with a finite basis set kinetic energy cut-off of 381.0 eV. Each geometry has been optimized using Broyden, Fletcher, Goldfarb, and Shanno's (BFGS) algorithm for 100 iterations with a fixed basis quality variable cell method and finite electronic minimization parameters. The phonon calculations were performed using TDFT with a kinetic energy cut of 460 eV in a norm-conserving linear response method. The interpolation with a finite dispersion quality and q-vector grid spacing is performed.

Terahertz permittivity parameters of monoclinic single crystal lutetium oxyorthosilicate

The anisotropic permittivity parameters of monoclinic single crystal lutetium oxyorthosilicate, Lu2SiO5 (LSO), have been determined in the terahertz spectral range. Using terahertz generalized spectroscopic ellipsometry (THz-GSE), we obtained the THz permittivities along the a, b, and c⋆ crystal directions, which correspond to the εa, εb, and εc⋆ on-diagonal tensor elements. The associated off diagonal tensor element εac⋆ was also determined experimentally, which is required to describe LSO's optical response in the monoclinic a–c crystallographic plane. From the four tensor elements obtained in the model fit, we calculate the direction of the principal dielectric axes in the a–c plane. We find good agreement when comparing THz-GSE permittivities to the static permittivity tensors from previous infrared and density functional theory studies.

Optical sensitivity of mono and hybrid nanomaterials dispersed PEG-based semiconducting nanofluids with high viscosity and dielectric permittivity

ABSTRACT Semiconducting nanofluids (SNFs), based on poly(ethylene glycol) (PEG200) fluid with the dispersion of 0.01 wt% mono (ZnO, TiO2, and OMMT) and 0.01+ 0.01 wt% hybrid (ZnO+OMMT, ZnO+TiO2, and TiO2+OMMT) nanomaterials, are prepared through mixing and then ultrasonic cavitation homogenised process. Ultraviolet-visible (UV-Vis) absorbance spectra of these SNFs are recorded in the 200–800 nm range and analysed for their photosensitivity and UV shielding performance and also for nanomaterials tunable dual band gaps ranging from 3 to 5 eV. The rheological investigations on these samples, at 303.15 K, validate Newtonian nanofluids of high dynamic viscosity (η ≈ 32 mP.s). Static dielectric permittivity (εs ≈ 22) and electrical conductivity (σdc ≈ 8 μS/cm) of these SNFs at 303.15 K are found marginally affected by the dispersed mono and hybrid nanomaterials. Comparative experimental results presented here in on a variety of SNFs provide a guideline for their uses in developing soft condensed matter based innovative devices.

Investigations on the optical, dielectric, electrical, and rheological properties of PEG200/ZnO semiconducting nanofluids for soft matter based technological innovations

Semiconducting nanofluids (SNFs) consisting of poly (ethylene glycol) (PEG200) as a green biocompatible base fluid with homogeneous dispersion of eco-friendly zinc oxide (ZnO) nanomaterial, concentrations ranging from 0.01 to 0.20 wt%, are prepared by state-of-the-art ultrasonic cavitation homogenized process. These PEG200/ZnO SNFs are characterized by employing an ultraviolet-visible (UV-Vis) spectrophotometer, precision inductance-capacitance-resistance (LCR) meter, and rotational viscometer. A detailed analysis of 200–800 nm range UV–Vis absorbance spectra of these SNFs revealed longer stability of suspended ZnO nanoparticles in PEG200 fluid, and their nanomaterial concentrations dependent absorbance and extinction coefficient with tunable dual energy band gaps ranging from 3 to 5 eV. Optical performance recognized the potential applications of these SNFs in the advances of soft matter based optoelectronic and photosensitive devices and also as an excellent UV radiation shielding material. The study of 20 Hz – 1 MHz range dielectric and electrical spectra explained that the ZnO concentrations have a significant impact on the electrical conductivity of these SNFs, while the dielectric permittivity and electrode polarization relaxation process are marginally altered. High static dielectric permittivity (∼ 22) and low electrical conductivity of about μS/cm order, at 303.15 K, evidence the suitability of these SNFs in advances of energy storage devices. The rheological behaviour of PEG200/ZnO materials is carried out at different temperatures ranging from 303.15 to 323.15 K, which illustrates the Newtonian characteristics of these nanofluids with moderate dynamic viscosity and activation energy, and therefore, they could be utilized as effective heat transfer materials in photovoltaic/thermal devices and systems.

First-principles study of the effect of doping on the optoelectronic properties of defective monolayers of MoSe2.

In this paper, the structural stability, electronic structure, and optical properties of monolayer MoSe2 doped with C, O, Si, S, and Te atoms, respectively, under defective conditions are investigated based on first principles. It is found that the system is more structurally stable when defecting a single Se atom as compared to defecting a single Mo or two Se atoms. The electronic structure analysis of the system reveals that intrinsic MoSe2 is a direct bandgap semiconductor. The bandgap value of the system decreases with a single Se atom defect and introduces two new impurity energy levels in the conduction band. The defective systems doped with C and Si atoms all exhibit P-type doping. The total density of states of intrinsic MoSe2 is mainly contributed by the Mo-d and Se-p orbitals, and new density of state peaks appears near the conduction band after the defects of Se atoms. The total density of states of the defective system doped by each atom is mainly contributed by Mo-d, Se-p, and the result of the p orbital contribution of each dopant atom. By analyzing the dielectric function of each system, it is found that the intrinsic MoSe2 has the lowest static permittivity and the C-doped defect system has the highest static permittivity, which reaches 21.42. The C- and Si-doped defect systems are the first to start absorbing the light, and the intrinsic MoSe2 absorbs the light later, with its absorption edge starting at 1.25eV. In the visible range, the reflection peaks of the systems move toward the high-energy region and the blue-shift phenomenon occurs. It is hoped that applying modification means to modulate the physical properties of the two-dimensional materials will provide some theoretical basis for broadening the application of monolayer MoSe2 in the field of optoelectronic devices. This study utilizes the first principle computational software package MS8.0 (Materials studio8.0) under density functional theory (DFT). The exchange-correlation potential (GGA-PBE) is described by the Perdew-Burke-Ernzerhof correlation function in CASTEP, and the potential function adopts the ultrasoft pseudopotential in the inverse space formulation. The plane wave truncation energy Ecut is set to 400eV, the K-point is taken as 5 × 5 × 1, and the force convergence criterion is 0.05eV/Å. The convergence accuracy of the total energy of the system is less than 1.0 × 10-5eV/atom, the tolerance shift is less than 0.002Å, and the stress deviation is less than 0.1 GPa. The vacuum layer is taken as 15Å, which is intended to minimize the interlayer force. The vacuum layer was set to 15Å to avoid the effect of layer-to-layer interaction forces in the crystal cell.

Effect of Water Adsorption on Lubricating Film Stability in Slippery Coatings.

The absorption of water by slippery coatings is a ubiquitous phenomenon that arises due to small but finite water dissolution during the contact of aqueous media with lubricants. In this study, using the concept of surface forces, we have analyzed the influence of trace amounts of water in lubricants on the stability of slippery coatings for both coatings with hydrophilic porous bases, prone to form hydrogen bonds with water, and those with hydrophobic porous bases. To perform such analysis, we have considered for the first time the electrostatic problem of the distribution of the electric potential and electric field strength in stratified films that contain two thin dielectric layers imitating the lubricant and a hydrophobic layer sandwiched between the porous substrate and air or water. Based on the developed approach, the equations for the calculation of the excess free energy and the disjoining pressure, associated with water dissolution in the lubricant film, were derived. An analysis of the excess film energy and the contribution of the image interaction to the disjoining pressure isotherm indicates that the dissolved water can both stabilize and destabilize the oil film, depending on the ratio of the static and dynamic dielectric permittivities of the lubricant and the phases confining the film. The results of calculations and simple experiments carried out here indicate much better water contact stability of silicone films impregnating a hydrophobized porous substrate than films impregnating a hydrophilic porous substrate. The obtained results indicate the preference for using the hydrophobic bases for the fabrication of long-lived slippery coatings characterized by better preservation of slippery functional properties under conditions of lubricant depletion and prolonged contact with water.

Определение диэлектрических свойств воды в тонком слое

A technique is proposed for determining the dielectric properties of water in a nanoscale layer at frequencies corresponding to orientation polarization. The method is based on the registration of the change in the velocity of elastic surface waves resulting from the interaction with a thin layer of a liquid. It was assumed that the dispersion of the dielectric permittivity of water in the thin layer is described by the Debye's equations of dielectric relaxation. In order to demonstrate the capabilities of the proposed method, the values of the real part of the dielectric permittivity of adsorbed water at various frequencies f (43.2; 64.8; 108; 129.6, 194.4, 302.4, 388.8 MHz) were experimentally determined at a fixed thickness of the adsorption layer h (2.2; 2.8; 3.7; 13 nm). The determination of the value of the imaginary part of the dielectric permittivity as well as the calculation of the time of dielectric relaxation, static, and high-frequency dielectric permittivities was enabled by the use of the experimental values and Debye's equations. A comparison was made between the dielectric properties of adsorbed water and those of water in the bulk liquid phase. The high-frequency dielectric permittivity of adsorbed water was found to be lower than that of water in the bulk liquid phase, while the static dielectric permittivity was significantly higher. The dielectric relaxation time of adsorbed water is dependent on the thickness of the adsorption layer and is significantly longer than that of water in the bulk liquid phase.

Observation of ferroelectric behaviour in non-symmetrical cholesterol-based bent-shaped dimers.

Non-symmetrical cholesterol-based dimers have emerged as crucial materials in the field of liquid crystal research, owing to their remarkable ability to stabilize various exotic mesophases, including the blue phases (BPIII, BPII, BPI), cholesteric nematic (N*) phase, smectic blue phase (SmBP), twist grain boundary (TGB) phase, smectic A/smectic A* (SmA/SmA*) phase, and smectic C/smectic C* (SmC/SmC*) phase. These mesophases have garnered considerable attention due to their diverse applications in spatial light modulation, chiro-optical devices, optical switching, thermochromic materials, and more. In this study, we present the synthesis and comprehensive characterization of a series of non-symmetrical cholesterol-based bent-shaped dimers (1/12, 1/14, 1/16) in which the cholesterol unit is intricately linked to an aromatic mesogenic core through a flexible spacer. These novel materials exhibit the intriguing ability to stabilize a variety of mesophases, including the N*, TGBA, SmA, and SmC* phases. The chiro-optical properties of the helical SmC* phase have been meticulously investigated through temperature-dependent chiro-optical measurements, shedding light on their potential for advanced optoelectronic applications. Additionally, we have conducted a thorough examination of the physical characteristics of these cholesterol-based dimers, including static permittivity measurements, dielectric spectroscopy, and electro-optical performance analysis. Remarkably, two homologues (1/14, 1/16) exhibit negative dielectric anisotropy, a crucial parameter for liquid crystal devices. Furthermore, our investigation reveals that these materials exhibit ferroelectric behaviour in the SmC* phase, with compounds 1/14 and 1/16 demonstrating substantial spontaneous polarization (PS) values of approximately 132 nC cm-2 and 149 nC cm-2, respectively. These findings underscore the potential of non-symmetrical cholesterol-based dimers as versatile components for the development of innovative electro-optical devices.