Optical Absorption Coefficient Research Articles

Photovoltaic Cell Prepared from Nanoparticles of CdS/CdTe on ITO Substrate and its Characterization

CdS/CdTe based photovoltaic cell has shown the markable efficiency. The CdS/CdTe nanoparticles are being synthesized and deposited on the ITO glass plate. ITO glass has a large bandgap of about approximately 3.6 eV and is suitable to use in the fabrication of photovoltaic cell. As ITO behaves as negative terminal, it is used as front layer for capturing the light intensity. During fabrication of photovoltaic cell, the deposition of Cadmium sulphide and Cadmium telluride nanoparticles layer was done by brush painting technique. The CdS layer is used as window layer and CdTe acts as absorbing layer. The window layer’s primary function is to absorb light particularly in the visible region of the spectrum to generate electricity. The CdS layer forms p-n junction with the CdTe layer. The nanoparticles of CdS and CdTe have been synthesized first and optical characterization was carried out using UV-visible spectroscopy to obtain bandgap of CdTe and CdS. Structural characterization was being obtained by XRD. The size of the nanocrystallites of CdS and CdTe have been obtained by Debye Scherrer equation and the result was 1.64 nm and 4.09 nm respectively. The CdTe layer which was used as absorbing layer consists of high optical absorption coefficient with high mobility, good carrier lifetime and an enhanced properties of crystallographic. Silver paste was used as a back contact for good conduction.

First-principles study of the electronic and optical properties of two-dimensional PtS2/GaS van der Waals heterostructure

Heterostructures based on two-dimensional materials have received increasing attention due to their extraordinary properties and application potential. In this paper, the electronic and optical properties of the PtS2/GaS van der Waals (vdW) heterostructure as well as the effects of biaxial strain and external electric field are systematically investigated based on first-principles calculations. The PtS2/GaS vdW heterostructure has an interlayer distance of 3.01 Å and is a type-Ⅱ semiconductor of band gap 1.54 eV. Large optical absorption coefficients are observed in both the ultraviolet and the visible regions. Furthermore, its band structure can be effectively tuned by applying biaxial strain and external electric field. The transition between the type-Ⅱ and type-I band alignments can be realized. The absorption spectra and their peaks can be then manipulated effectively by applying biaxial strain with good stability under external electric field. The predicted tunable electronic properties and unique optical absorption properties suggests promising potential for the application of the PtS2/GaS vdW heterostructure in future optoelectronic nanodevices.

Anisotropic optical property of ferroelectric Bi2O2X(X = S,Se,Te) monolayer and strain engineering

Based on the first-principles calculations, ferroelectric Bi2O2X(X = S,Se,Te) monolayers with unequivalent in-plane lattice constants are confirmed to be the ground state, which is consistent with the experiment result (Ghosh et al 2019 Nano Lett. 19 5703–09), and the anisotropic optical property is firstly investigated. We find that the polarizations of Bi2O2X monolayers points along the direction of a-axis, and Bi2O2Te monolayer process the largest polarization. Furthermore, both the biaxial and uniaxial strains are favor for the enhancement of polarization of Bi2O2X monolayers. It should be mentioned that the type of band gap will convert from indirect to direct for Bi2O2Te monolayer when the a-axial tensile strain is larger than 2%. At last, the optical absorption coefficient for Bi2O2X monolayers are calculated, and we obtain that Bi2O2Te monolayer has the strongest optical absorption within the range of visible light, the anisotropy and possible strain engineering to improve the optical absorption are discussed in detail. Our findings are significant in fields of optoelectronics and photovoltaics.

Study of Fabrication Process and Performance Analysis of the CDS/CDTE Based Photovoltaic Cell

Fabrication of CDS/CDTE based heterojunction photovoltaic cell has been undertaken to explore better light conversion efficiency. We have developed a photovoltaic cell using glass coated with Indium doped Tin Oxide (ITO) which works as transparent conducting oxide (TCO). ITO coated glass has promising prospects of enhancing the efficiency of the photovoltaic cell. ITO layers are known to be employed as anode terminal due to the negative polarity they possess compared to the whole PV cell; here, we have employed it for the same function as the front layer. During fabrication of the photovoltaic cell, the deposition of nanoparticles of CDS and CDTE layer is undertaken through doctor-blade method. We have employed pure CDS as window layer for its high band gap of 3.8 eV (particle size: 8 nm) and CDTE as absorber layer due to its high optical absorption coefficient with high mobility, good carrier lifetime and enhanced crystallographic properties. The CDS window layer and CDTE absorber layer together constitute a p-n junction where the CDS window layer captures high intensity photons and transmits the photo-excited electron to CDTE absorber layer, thereby leading to photo-current output, which serves as a base to explore and test its further applications. To obtain band gap of respective CDTE and CDS nanoparticles, optical characterization is used. Silver paste is used as rear contact to form anode terminal having good conductivity and providing better mechanical support to the photovoltaic cell.

Theoretical study on photoelectric properties of ferroelectric photovoltaic perovskite CsGeBr3 based on first-principle calculations

Ferroelectric photovoltaic materials have attracted great attention because of their unique photoelectric conversion mechanism, high photo-generated voltage, and adjustable polarization intensity. Traditional ferroelectric oxide perovskites such as BaTiO3, BiFeO3, and Pb(ZrTi)O3 have attracted much attention but they are not suitable as light absorbing layers in solar cells, due to the large optical bandgap, low light absorption rate, and small photogenerated current. Therefore, it is necessary to seek prominent materials with both ferroelectric and suitable band gaps. Recently, the evidence of ferroelectricity in the typical three-dimensional all-inorganic halide perovskites CsGeX3, with band gaps of 1.6 eV to 2.3 eV has been confirmed. However, the spontaneous polarization of ferroelectric perovskite CsGeX3 is ∼10 to 20 μc cm−2 which is weaker than that of ABO3 (∼26 to 75 μc cm−2). Strain engineering has a significant influence on the properties of semiconductor materials by controlling the lattice scaling and the internal atomic spacing. Hence, in this work, strain engineering is introduced to adjust the ferroelectric polarization and the photoelectric properties of ferroelectric perovskite CsGeBr3. The calculated results show that when the applied compressive strain increases from 0% to −4%, the spontaneous polarization of ferroelectric perovskite CsGeBr3 increases from 14.23 μc cm−2 to 51.61 μc cm−2, and the band gap reduces from 2.3631 eV to 1.5310 eV. The effective mass of electrons and holes gradually reduces, exciton binding energies decrease from 48 meV to 5 meV, and the optical absorption coefficient is strongly enhanced from 3 × 105 cm−1 to 5 × 105 cm−1 in the visible range. Besides, the power conversion efficiency(PCE) of CsGeBr3 is significantly increased from 16.95% to 26.77%. Therefore, the results indicate that the application of compressive strain can increase the ferroelectric polarization and enhance the original photovoltaic performance of ferroelectric perovskite CsGeBr3. Our theoretical calculations can provide useful insights and beneficial guidance into experimental studies of ferroelectric perovskites in photoelectric applications.

Impact of PCBM as a Third Component on Optical and Electrical Properties in Ternary Organic Blends.

This paper investigates the influence of constituent weight ratios on optical and electrical properties, with a particular focus on the intrinsic properties (such as electrical mobility) of ternary organic blends, highlighting the role of a third component. The study explores novel donor:acceptor1:acceptor2 (D:A1:A2) matrix blends with photovoltaic potential, systematically adjusting the ratio of the two acceptors in the mixtures, while keeping constant the donor:acceptor weight ratio (D:A = 1:1.4). Herein, depending on this adjustment, six different samples of 100-400 nm thickness are methodically characterized. Optical analysis demonstrates the spectral complementarity of the component materials and exposes the optimal weight ratio (D:A1:A2 = 1:1:0.4) for the highest optical absorption coefficient. Atomic force microscopy (AFM) analysis reveals improved and superior morphological attributes with the addition of the third component (fullerene). In terms of the electrical mobility of charge carriers, this study finds that the sample in which A1 = A2 has the greatest recorded value [μmax=1.41×10-4cm2/(Vs)]. This thorough study on ternary organic blends reveals the crucial relationship between acceptor ratios and the properties of the final blend, highlighting the critical function of the third component in influencing the intrinsic factors such as electrical mobility, offering valuable insights for the optimization of ternary organic solar cells.

Strain modulated optical properties of MoSi2P4 monolayer – insights from DFT

Strain plays a very important role in tuning the properties of the materials for the desired applications. In the present work, we have investigated the variation of strain on the electronic and optical properties of a recently synthesized class of compound MoSi2P4 monolayer using the first principle methods. The MoSi2P4 monolayer is found to be dynamically and thermally stable at room temperature. The electronic structure of studied monolayer indicates a direct bandgap (at K-point) of 0.685 eV and 1.177 eV using the PBE and HSE06 hybrid functionals, respectively. To tune the electronic bandgap and optical properties, mechanical strain was applied (up to ±10%). A high optical absorption coefficient of the order of 105 cm−1 is observed. The absorption starts in the infrared and visible region covering a large part in the ultraviolet region. The absorption coefficient is found to decrease (increase) under tensile (compressive) strain. Our study indicates the potential application of MoSi2P4 monolayer in flexible optoelectronic devices for absorption and detection in the infrared, visible and ultraviolet region.

Kerr coefficient and third-order nonlinear optical absorption coefficient of isotropic diacrylate mesogens at 632.8 nm wavelength

ABSTRACT Third-order optical nonlinearities of diacrylate mesogens RM82 and RM257 in the isotropic phase for a low-power continuous wave laser irradiation at 632.8 nm wavelength have been studied. In their isotropic state, the diacrylate mesogens exhibit quite large nonlinear absorption. We observe a large two-photon absorption coefficients, on an order of 10−6 m/W, for the mesogens. The Kerr coefficients of the mesogens are characterised using single beam Z-scan technique, and found to reach an order of 10−7 m/W. Both diacrylate mesogens exhibit a good material figure of merit.

Optical Properties of Tlinse2<Au> Single Crystals

This paper presents the results of studying the surface microrelief in 2D and 3D models and analyzing the spectroscopy of a three-junction TlInSe2<Au> crystal. Analysis of the results obtained showed that with a change in the composition of the TlInSe2<Au> crystal, sharp changes occur in the microrelief of its surface. An X-ray optical diffraction analysis of the TlInSe2<Au> crystal was experimentally carried out. Based on ellipsometric data, optical functions were determined - the real and imaginary parts of the dielectric permittivity of crystals, the coefficients of optical absorption and reflection, the dependence of energy losses and electric field power on the effective density, the spectral dependences of the real (σr) and imaginary (σi) parts, optical electrical conductivity were experimentally studied. The fluorescence spectra of the ternary compound TlInSe2<Au> were isolated and analyzed when excited by light with a wavelength of 532 nm. X-ray studies of TlInSe2<Au> showed that this phase crystallizes into tetragonal systems. Ellipsometric measurements showed that the real (ε1) and imaginary (ε2) parts of the dielectric constant are components of the dielectric constant tensor of the uniaxial joints under consideration and do not depend on the angle. Analysis of the dependence of the real and imaginary parts of the refractive index of the TlInSe2<Au> crystal on photon energy showed that the nature of the change in the real and imaginary parts of the dielectric constant does not differ significantly. When analyzing the spectral dependences of the real (σr) and imaginary (σi) parts of the optical electrical conductivity, it was noticed that the real part of the optical electrical conductivity increases exponentially in the energy range 0.894-3.505 eV. In the energy range of 0.654-2.91 eV, the imaginary part of the optical electrical conductivity increases linearly, reaches a maximum value, and decreases at an energy of 2.91 eV. At 3.6 eV, an inversion of the imaginary part of the optical electrical conductivity of the TlInSe2<Au> compound is observed. From the graphs of the effective power density versus electric field energy losses, it is known that the effective power density increases significantly in the energy range of 0.805–3.52 eV. The fluorescence spectrum of the ternary compound TlInSe2<Au> upon excitation with light with a wavelength of 532 nm has been studied and it has been established that this phase has luminescent properties.

Effect of Sulfur on Characterization of AgInSe1.8S0.2 Thin Film and n-AgInSe1.8S0.2 / p-Si Solar Cell

Ternary Silver Indium selenide Sulfur AgInSe1.8S0.2 in pure form and with a 0.2 ratio of Sulfur were fabricated via thermal evaporation under vacuum 3*10-6 torr on glasses substrates with a thickness of (550) nm. These films were investigated to understand their structural, optical, and Hall Characteristics. X-ray diffraction analysis was employed to examine the impact of varying Sulfur ratios on the structural properties. The results revealed that the AgInSe1.8S0.2 thin films in their pure form and with a 0.2 Sulfur ratio, both at room temperature and after annealing at 500 K, exhibited a polycrystalline nature with a tetragonal structure and a predominant orientation along the (112) plane, indicating an enhanced degree of crystallinity. The Atomic Force Microscopy (AFM) was utilized to explore how Sulfur affects roughness of surfaces and sampls Grain Size. Furthermore, optical parameters, such as the optical gap and absorption coefficient, were calculated to assess the influence of Sulfur on the optical properties of the AgInSe1.8S0.2 thin films. The UV/Visible measurements indicated a reduction in the energy band gap to 1.78 eV for AgInSe1.8S0.2 at 500 K, making these films potentially suitable for photovoltaic applications. These thin films exhibited donor characteristics, with an increase in electron concentration observed with higher Sulfur content and annealing temperature.

Photoresponse in sequentially stacked antimony selenide thin films

Antimony selenide (Sb2Se3), a binary semiconducting compound has widespread research attention due to its excellent optoelectronic properties in the visible region and usefulness in applications such as solar cells, photosensors and photoelectrodes. The presented study explores the thickness dependent photoresponse in Sb2Se3 thin films, prepared by reactive selenization of antimony films having thickness values of ∼938 nm and ∼1879 nm when stacked second time. Growth orientation along [001] direction was achieved through carefully optimized selenization conditions to enable favourable charge transport in anisotropic Sb2Se3. Predominant Sb2Se3 formation was inferred from x-ray diffraction, Raman spectroscopy, secondary electron microscopy and energy-dispersive X-ray analyses. High optical absorption coefficient values of about 1 × 105 cm−1 and 5.7 × 104 cm−1 were observed for ∼938 nm and ∼1879 nm thick Sb2Se3 thin films. Further, the optoelectronic properties were elucidated through current–voltage and transient photoresponse measurements under dark and illumination conditions. The measurements were done under zero and different bias voltages. Sb2Se3 films having∼ 938 nm thickness exhibited self-driven photoresponse with a responsivity of 4.3×10−8 A W−1 and detectivity of 3.5 × 106 jones respectively, under AM 1.5 G illumination conditions.

Photocatalytic activity and mechanism of YMnO3/NiO photocatalyst for the degradation of oil and gas field wastewater.

One-step hydrothermal method has been used to synthesize YMnO3@NiO (YMO@NO) photocatalysts with high photocatalytic activity for the degradation of oil and gas field wastewater under simulated solar irradiation. Through various characterization methods, it has been confirmed that the YMO@NO photocatalyst comprises only YMO and NO, without any other impurities. The microstructure characterization confirmed that the YMO@NO photocatalyst was composed of large squares and fine particles, and heterojunction was formed at the interface of YMO and NO. The optical properties confirm that the YMO@NO photocatalyst has high UV-vis optical absorption coefficient, suggesting that it has high UV-vis photocatalytic activity. Taking oil and gas field wastewater as degradation object, YMO@NO photocatalyst showed the highest photocatalytic activity (98%) when the catalyst content was 1.5g/L, the mass percentage of NO was 3%, and the irradiation time was 60min. Capture and stability experiments confirm that the YMO@NO photocatalyst is recyclable and electrons, holes, hydroxyl radicals and superoxide radicals play major roles in the photocatalysis process. Based on experiments and theoretical calculations, a reasonable photocatalytic mechanism of the YMO@NO photocatalyst is proposed.

A holistic approach of strain-induced and spin-orbit coupling governed structural, optical, electrical and phonon properties of Janus MoSSe heterostructure via DFT theory

Spintronics and optoelectronic equipment benefit from efficient modification of electrical and optical characteristics for Van der Waals heterostructures. Janus MoSSe, in two dimensions, has superior electronic, optical, and phonon properties. Based on these characteristics, we evaluate the effects of biaxial compressive and tensile strain ranges of −6% to +6% on the structural, optical, spin–orbit coupling, and phonon properties of two-dimensional MoSSe employing first-principles-based density functional theory calculations. At K-point, MoSSe possesses a direct band gap of 1.665 eV, making it a semiconductor. Yet, applying tensile strain, we can observe that the bandgap of MoSSe has declined. On the other hand, the bandgap of MoSSe rises due to the compressive strain. From the phonon properties, it is clear that the stability of the monolayer MoSSe is observed in the case of tensile strain. With the increase of compressive strain, it loses its stability. With a photon energy of 2.5 eV, MoSSe exhibits three times greater optical absorption than other photon energy levels. In comparison to two monolayers (MoS2, MoSe2), the MoSSe heterostructure shows an elevated optical absorption coefficient in the visible light band, according to our calculations of its dielectric constant and optical absorptionThe MoSSe dielectric constant’s peaks shift to the stronger photon energy as compressive strain is increased; in contrast, if tensile strain is added, the highest points shift to the less powerful photon energy. This suggests that the spin–orbit coupling (SOC) in MoSSe heterostructures can be enhanced under strain, which has implications for spintronics. The effect of strain can be used to tailor the phonon behaviors of MoSSe, which can be useful for controlling the material’s mechanical and thermal characteristics. The versatility of the electronic and optical properties of the material under strain can be harnessed to design novel devices such as strain sensors, optoelectronic modulators, and detectors.

The combination of DFT and OghmaNano framework to study the heat stability and minimizing voltage losses in perovskite solar cells

This study employs DFT calculation to inspect the influence of Zirconium (Zr) element on heat stability and minimizing voltage losses in perovskite solar cells (PSCs) electron transport layer (ETL) constructed from TiO2 bulk semiconductor. The band structure (BS), density of states (TDOS and PDOS), optical dielectric properties, refractive index, extinction coefficient, absorption coefficient, and energy loss phenomena for both pristine TiO2 and Zr-doped TiO2 were comprehensively analyzed. To keep the empirical results consistent, organic and hybrid material Nano (OghmaNano) simulation tools were used to simulate the behavior of 6.25 % Zr-doped TiO2 as an ETL within PSCs. Further simulation explored PSCs' electrical and optical behavior utilizing CH3NH3PbI3 with Zr-doped TiO2 as the ETL. Crucial parameters were determined, including charge carrier density, charge carrier recombination, quantum efficiency, I–V characteristics, device performance, and heat stability. The significant results of this study establish the fact that Zr doping into the TiO2 produces good device performance and maintains thermal stability in PSCs. Interestingly, the band gap achieved from BS and the density of states for pure and doped TiO2 were almost the same. A comparative evaluation of the effects of double ETL structure devices, shedding light on their distinctive contributions to device architecture, was presented. This research provides valuable insights into optimizing efficiency and stability in PSCs for sustainable energy applications.

Influence of Hot Carrier Cooling and Band‐Filling Effect on Linewidth of Perovskite Microlasers

AbstractIn semiconductor‐based microlasers, the generated excited carriers can affect both the optical absorption coefficient and refractive index, influencing the lasing behavior and device performance. In this study, the lasing behavior of individual MAPbBr3 microrods pumped by femtosecond laser pulses is investigated using an ultrafast optical Kerr gating technique. By analyzing the spectral and temporal evolution of the lasing behavior, it is found that the band‐filling (BF) effect can cause a significant change in the refractive index of the material, which results in an unfavorable red‐shift and broadening of the resonant modes, deteriorating the laser linewidth and quality factor. The hot carrier cooling process can provide a buffer for alteration of the energy level occupation state, resulting in a small transient refractive index change and slight red‐shift. These results offer insights into the lasing behavior driven by photogenerated carrier dynamics and provide an optimization strategy for semiconductor‐based microlasers.

Exploring the influence of the contact resistance on perovskite phototransistors

Organic–inorganic hybrid perovskites are widely used in photodetection owing to their high optical absorption coefficients. A variety of research has been conducted on perovskite phototransistors and their optoelectronic properties, but the exploration of the influence of contact resistance remains limited. In this work, we employed the transmission-line method to separate the contact resistance Rc × W (ranging from 4.81 × 104 to 4.77 × 103 Ω cm) and the channel resistance Rch × W (ranging from 1.93 × 104 to 1.16 × 104 Ω cm) of (PEA)2SnI4 perovskite phototransistors at different light intensities (520 nm, ranging from 0 to 2550 μW/cm2). Further analysis reveals that illumination-induced accumulation of charge carriers at the metal/semiconductor interface reduces the Schottky barrier. Approximately 90% of the observed increase in photocurrent can be attributed to the reduction in the contact resistance. Our finding underscores the crucial role of charge injection in influencing perovskite-based phototransistors.

A DFT Investigation for structural, electronic, optical, and elastic properties of inorganic oxide perovskites CsXO3 (X = Ti, Mn, Cu) for photosensitive applications

The investigation of inorganic oxide perovskites, specifically CsXO3 (X = Ti, Mn, Cu), has been carried out utilizing density functional theory (DFT) to gain deeper insights into their structural electronic, optical, and elastic attributes. The calculated band gaps for CsTiO3, CsMnO3 and CsCuO3 are determined to be 1.68 eV, 3.26 eV, and 4.62 eV, respectively, while the lattice parameters are measured at 4.098 Å, 3.987 Å, and 4.059 Å. Our findings indicate that CsMnO3 and CsCuO3 possess moderate-sized, indirect band gaps, showcasing potential for enhanced conductivity. And CsTiO3 shows direct band gap. Additionally, CsTiO3 and CsCuO3 exhibit ductile and anisotropic behavior, as evidenced by both Poisson's ratio and the anisotropic factor. And CsMnO3 shows brittle nature. The anisotropic factors are 2.14 for CsTiO3, 1.99 for CsMnO3, and 1.89 for CsCuO3, whereas the Poisson's ratios are measured at 0.45, 0.34, and 0.49, respectively. Notably, CsTiO3 demonstrates significant photovoltaic activity within the visible spectrum, accompanied by a high optical conductivity and absorption coefficient, positioning it as a promising material for solar cell applications. The favorable attributes of CsTiO3 suggest its potential suitability for integration in optical and electronic devices.

Effect of metal (Cr, Sr, Ag, Cu) doping on the performance of lead-free RbSnI3 based perovskite solar cells: A theoretical approach

Perovskite solar cells based on lead have witnessed unprecedented growth over the past decade, achieving an impressive power conversion efficiency (PCE) of 26.1%. However, lead toxicity remains a concern for commercialization. In order to resolve the matter, scientists have been investigating alternative materials; in this context, rubidium-based lead-free perovskites like RbSnI3 may be a promising alternative because it has a high optical conductivity and absorption coefficient. Density Functional Theory (DFT)-based first-principles studies are used in this work to examine the effect of metal doping (specifically Cr, Sr, Ag, and Cu) on the optoelectronic and structural characteristics of orthorhombic RbSnI3 perovskite. In addition, we conducted a comprehensive study to investigate the impact of metal doping on the formation energy, structural stability, and HOMO–LUMO energy levels of RbSnI3 perovskite. Introducing transition metal cations (Cr2+, Ag+, and Cu+) at the Rb site results in a flat band in the conduction band region, transforming the RbSnI3’s indirect band gap into a direct one and significantly affecting the optoelectronic properties. The DFT results are then integrated into the Solar Cell Capacitance Simulator (SCAPS-1D) to estimate the effectiveness of the modeled device. The Cu-doped RbSnI3 device exhibits the highest PCE of 20.2%. Furthermore, Ag and Cu doping in RbSnI3 increases bond length, which reduces exciton binding energy and helps with charge carrier generation.

Exploring the microscopic effects of surrounding matrices (HfO2 and SiO2) on CdSe/ZnS and ZnS/CdSe cylindrical core/shell quantum dot for microelectronic transport applications

The primary goal of this study is to comprehensively describe the physical impact of surrounding dielectrix oxides on the electronic and optical properties of a confined electron within CdSe/ZnS and ZnS/CdSe cylindrical core/shell quantum dot (CCSQD). The effective mass approximation and the compact density matrix approach have been employed to compute the energy eigenvalues as well as the optical absorption coefficients (OACs) and the refractive index changes (RICs). Our calculations revealed that the presence of enveloping oxides acts as an additional confinement tool altering the electron energy spectrum. The ZnS/CdSe CCSQD exhibited more pronounced response and the exploitation of the local electric factor can effectively enhance the optical nonlinearity of OACs and RICs. We demonstrated that confined electrons within the ZnS/CdSe CCSQD are subjected to an intense interaction at the microscopic scale with the host medium. In addition, saturation effects in the nonlinear computed coefficients have been meticulously analyzed in terms of size and dielectric surroundings. Our findings demonstrated that electronic band edge states are heavily impacted by the sharp dielectric mismatch occurring at QD/matrix interface which could be exploited for the creation of novel optoelectronic devices in the future.

Comparative first principles investigation on the structural, optoelectronic and vibrational properties of strain-engineered graphene-like AlC3, BC3 and C3N monolayers

Three cardinal two-dimensional semiconductors viz., AlC3, BC3 and C3N, closely resembling the graphene structure, are intriguing contenders for emerging optoelectronic and thermomechanical applications. Starting from a critical stability analysis, this density functional theory study delves into a quantitative assessment of structural, mechanical, electronic, optical, vibrational and thermodynamical properties of these monolayers as a function of biaxial strain (ε) in a sublinear regime (−2%⩽ε⩽4%) of elastic deformation. The structures with cohesive energies slightly smaller than graphene, manifest exceptional mechanical stiffness, flexibility and breaking stress. The mechanical parameters have been deployed to further cultivate acoustic attributes and thermal conductivity. The hexagonal structures with mixed ionic-covalent molecular bonds have indirect electronic band-gap and work-function acutely sensitive to ε . Dispersions of optical dielectric function, energy loss, refractive index, extinction coefficient, reflectivity, absorption coefficient and conductivity are deciphered in the UV–Vis–NIR regime against strain, where particular frequency bands featuring high polarization, dissipation, absorbance or reflectance are identified. Phonon band-structure and density of states testify dynamic stability in the ground state for all systems except the compressed ones. A comprehensive group theoretical analysis is performed to cultivate rotational; infrared and Raman-active modes, and the nature of molecular vibrations is delineated. The red-shifting of phonon bands and E2g/A1g Raman peaks with increasing ε , associates estimation of Grüneisen parameter. Finally, strain-induced alterations of thermodynamic quantities such as entropy, enthalpy, free energy, heat capacity and Debye temperature are studied, followed by a molecular dynamics-based stability assessment under canonical ensemble.