Journals
2026 EN
Nyayban Anupriya · Das Mousumi
ABSTRACT All inorganic perovskite materials have received significant attention in the photovoltaic devices due to their remarkable optoelectronic properties. Although the efficiency ofRbPbBr 3 ${\rm RbPbBr}_3$ has been reported to increase using various electron transport layers, it is also crucial to improve the performance of the absorber layer ofRbPbBr 3 ${\rm RbPbBr}_3$ . In this work, density functional theory (DFT) and ab initio molecular dynamics (AIMD) were performed for investigating the structural, electronic, and optical properties of tetragonalRbPbBr 3 ${\rm RbPbBr}_3$ perovskite under different pressure. The results indicate that the bandgap can be tuned from2.01 $2.01$ to1.27 $1.27$ eV under the application of pressure from0 $\hskip.001pt 0$ to30 $\hskip.001pt 30$ GPa, using Heyd–Scuseria–Ernzerhof (HSE) hybrid functional including spin–orbit coupling (SOC) effect. The change in the bandgap is primarily influenced by variations in the Pb‐Br‐Pb bond angle and the short and the long bond length of Pb‐Br under pressure ranging from0 $\hskip.001pt 0$ to30 $\hskip.001pt 30$ GPa. A suitable bandgap of1.37 $1.37$ eV can be achieved at a pressure of20 $\hskip.001pt 20$ GPa, making it promising for the photovoltaic applications. The anharmonic phonon spectra at300 $\hskip.001pt 300$ K indicates the structural stability under different pressure considered. The narrowing of the bandgap implies a redshift in the absorption spectra. Moreover, the effective masses of conduction electrons and holes decrease, and excitons become weaker with increasing pressure. The exciton type changes from Frenkel to Mott–Wannier at pressure beyond15 $\hskip.001pt 15$ GPa. These results are crucial for understanding the effects of pressure on the photovoltaic properties of tetragonalRbPbBr 3 ${\rm RbPbBr}_3$ perovskite, and this can guide the experiments aimed at improving the photovoltaic performance of all inorganic perovskites.
Journals
2026 EN
Tiwary Ashish · Kumar Jitendra · Lukose Vivek
+1 more
ABSTRACT This article provides a comprehensive performance analysis of various sensing layers on one‐port surface acoustic wave (SAW) resonators exhibiting mass loading effect. Lithium Niobate (LiNbO 3 ) piezoelectric substrate, polyisobutylene (PIB) polymer and carbon nanotube (CNT) based multilayer SAW sensors were considered for device sensitivity. This study contributes to understanding the CNT‐PIB composite layer on 128° YX‐cut LiNbO 3 SAW devices for sensing applications. This research proposed four different SAW structures with optimized geometrical boundary conditions. The finite element method is applied to solve the SAW device partial differential equation (PDE) to find the device performance parameters. The proposed one‐port SAW sensor has been analyzed with the investigation of change in SAW phase velocity, electromechanical coupling coefficient ( K 2 ), device sensitivity, admittance (Y11), S parameter (S11), and quality factor. Electrical response of the proposed SAW device is equivalently modeled with the modified Butterworth‐Van Dyke (mBVD) lumped parameters, motional resistance ( R m ), motional inductor ( L m ), motional capacitor ( C m ), and electrostatic capacitance ( C 0 ). The obtained mBVD parameter describes the proposed SAW device's behavior tuned to the desired sensitivity, frequency response and signal‐to‐noise ratio. High sensitivity of 18.7 MHz/µg is reported for the proposed device. The obtained mass sensitivity is compared and is more effective than the parallel research outcome.
Journals
2026 EN
Sharma Pooja · Ranjan Prabhat · Chakraborty Tanmoy
ABSTRACT Perovskite materials have emerged as a focal point for scientific research, owing to their ability for plausible applications in optoelectronic and photovoltaic systems. We have explored Al‐based fluoro‐perovskite compounds AlMF 3 (M = Ca, Zn, Ge) studied through Density Functional theory (DFT) and Time‐Dependent (TD)‐DFT methodology. Functional CAM‐B3LYP/ LanL2MB and CAM‐B3LYP/LANL2DZ are employed for geometry optimization. This study examined the structural, optoelectronic, and thermochemical properties of these materials. The tolerance factors of AlCaF 3 , AlZnF 3, and AlGeF 3 are found as 0.85, 0.93, and 0.96. The negative formation energy of AlMF 3 compounds indicates thermodynamic stability. The HOMO–LUMO gap of AlCaF 3 , AlZnF 3 , and AlGeF 3 using LANL2MB is obtained as 2.82, 2.44, and 2.40 eV, respectively, whereas using LANL2DZ it is found in the range of 1.90–2.40 eV. AlGeF 3 and AlCaF 3 exhibit a minimum and maximum energy gap, respectively. CDFT‐based descriptors of AlMF 3 are analyzed and discussed. Among the examined fluoro‐perovskites, AlCaF 3 exhibits high stability. AlGeF 3 shows the maximum value of electronegativity, which indicates that it has high electron‐accepting capability. The refractive index and dielectric constant of these fluoro‐perovskite increase as the replacement of the M‐site cation, Ca to Zn to Ge, takes place. The thermochemical properties of these materials are also calculated. The estimated findings show a pattern consistent with earlier reports on perovskite materials.
Journals
2026 EN
AyalaRuano A.S. · OlivaAvilés A.I.
ABSTRACT A carbon nanotube (CNT) interconnected network model is proposed to evaluate the electrical properties of polymer nanocomposites through a resistor‐inspired approach. The model is able to control morphological characteristics of CNTs such as length, degree of orientation, and waviness, and then analyze their impact on the effective electrical conductivity of polymer nanocomposites. An algorithm based on stochastic elements to generate, identify, and analyze interconnected CNTs networks by assigning equivalent electrical resistances is developed. For each case, electrical resistance values were assigned to the CNT network considering CNT‐CNT contact, electron tunneling, and intrinsic conduction mechanisms. The model was able to identify and correlate the impact of each type of CNT‐CNT interactions (direct contact/tunneling) on the global electrical properties, confirming the tunneling mechanism as the main driver at the electrical percolation stage. Longer, straighter, and moderately aligned CNTs generate nanocomposites with more electrical pathways. The model is capable to adequately predict experimental reports, evidencing its relevance for the optimization of CNT‐based nanocomposites for technological applications.
Journals
2026 EN
Nguyen Duy Khanh · Ly Nguyen Hai · Ha Chu Viet
+4 more
ABSTRACT In this work, we propose novel doping approaches to induce sp magnetism inGeI 2 ${\rm GeI}_{2}$ monolayer. Pristine monolayer is a nonmagnetic 2D semiconductor with a relatively large indirect gap of 2.10 eV, whose Ge‐I chemical bond is proven to exhibit both covalent and ionic characters. Arsenic (As) impurity induces the in‐plane magnetic anisotropy (IMA) with total magnetic moments of 1.00 and 2.00μ B $\mu _{B}$ when doping at Ge ( As G e ${\rm As}_{Ge}$ ) and I ( As I ${\rm As}_{I}$ ) sublattices, respectively. The out‐of‐plane magnetic anisotropy (PMA) with overall magnetic moment of 2.00μ B $\mu _{B}$ is achieved by doping with Selenium (Se) atom at Ge site ( Se G e ${\rm Se}_{Ge}$ ), meanwhile the nonmagnetic nature ofGeI 2 ${\rm GeI}_{2}$ monolayer is preserved when Se impurity is incorporated at I site ( Se I ${\rm Se}_{I}$ ). The PMA can be also induced by doping with pair As and Se atoms (pAs and pSe). Interestingly, the half‐metallicity is obtained in all the magnetic dopedGeI 2 ${\rm GeI}_{2}$ systems, where impurities and their neighboring atoms produce mainly the magnetism and regulate the electronic properties. Further, As and Se codoping is found to reduce significantly the monolayer band gap. Herein,As G e ${\rm As}_{Ge}$ + Se I ${\rm Se}_{I}$ andAs I ${\rm As}_{I}$ + Se G e ${\rm Se}_{Ge}$ doping configurations determine the reduction rates of 12.86% and 50.48%, respectively. In addition, our calculations show that impurities incorporated at Ge sublattice lose charge, meanwhile those doped at I sublattice attract charge from the host monolayer. Our findings may introduce effective sp doping approaches to makeGeI 2 ${\rm GeI}_{2}$ monolayer suitable for spintronic and optoelectronic applications.
Journals
2026 EN
Abdullah Ahmed Choukri · Tasoglu Savas
ABSTRACT The integration of microrobotic stents into biomedical applications has the potential to revolutionize invasive procedures by enabling precise drug delivery, imaging, and vascular interventions. These interventions demand alloys with high radial stiffness for structural integrity and low density for biocompatibility. We developed a machine learning (ML)‐finite element analysis (FEA) framework to optimize titanium (Ti)‐based and Ti‐based high‐entropy alloys (Ti‐HEAs) compositions using a curated database of 238 alloys. Gaussian process regression (GPR) is trained on FEA‐simulated radial stiffness and constrained optimization (interior‐point, sequential quadratic programming (SQP), active‐set) identified high‐performance candidates. The interior‐point algorithm yielded the highest stiffness (483.54 kN/m) with balanced composition (Ti: 76.29 at%, Nb: 6.88%, Zr: 7.34%, Ta: 7.31%), outperforming the dataset maximum (TiSn 20, 472.49 kN/m) by 2.32% and Ti‐6Al‐4 V (368.96 kN/m) by 31%. All algorithms converged to at least 469 kN/m despite compositional diversity, confirming robustness. The framework enables rapid, physics‐informed alloy design for next‐generation biomedical microrobotics.
Journals
2026 EN
Rana Md. Zuel · Hasan Jahid · Islam Md. Saiful
+6 more
ABSTRACT This study offers a comprehensive first‐principles study on the electrical, thermodynamic, and optical characteristics of the cubic perovskite CsTaO 3 and CsNbO 3 with an emphasis on their potentials in energy conversion applications. We systematically analyze their electronic band structures using DFT with the GGA; improved by hybrid functional corrections (HSE06). The bandgaps predicted by HSE06 are 2.42 (0 GPa) and 1.67 eV (100 GPa) for CsTaO 3 , whereas GGA‐PBE yields 1.43 and 0.94 eV, respectively. In comparison to 1.36 and 1.01 eV with GGA‐PBE, the band gaps for CsNbO 3 are 1.59 (0 GPa) and 1.32 eV (100 GPa) with HSE06. Direct bandgap in the visible region, and optical calculations indicate that CsNbO 3 can be used for photovoltaic systems and photocatalysis. A solar cell model of CsXO 3 (X = Ta, Nb) exhibits the band alignment of charge transport layers and substantial optical absorption throughout the visible range, suggesting a high potential for solar‐to‐electric conversion. The results of this study indicate that the optimized device on CsNbO 3 could achieve an outstanding power conversion efficiency (PCE) of 28.79%, which is higher than PEC of CsTaO 3 (25.47%). These materials can be theoretically understood through this study, resulting in energy harvesting and conversion technologies, especially photocatalysis and photovoltaics.
Journals
2026 EN
Yacham Ashok · Patra Tarak K. · Varghese Jithin John
ABSTRACT Understanding how gas mixtures diffuse and distribute within porous frameworks is central to designing advanced separation and storage materials. Here, the transport and spatial distribution of binary gas mixtures in a porous metal‐organic framework, viz., ZIF‐90, using molecular simulations is investigated. We performed grand canonical Monte Carlo (GCMC) simulations to examine the competitive adsorption of carbon dioxide (CO 2 ) and nitrogen (N 2 ) from a binary gas mixture in ZIF‐90, while molecular dynamics (MD) simulations are conducted to investigate the transport behavior of the adsorbed molecules within the framework. These integrated simulations reveal that the framework topology and pore chemistry jointly dictate diffusion pathways and preferential occupancy of gas species, underscoring their intrinsic interdependence. Competitive adsorption leads to distinct spatial partitioning within the pores, which in turn modulates mixture diffusivity inside the porous medium compared to their bulk properties. These results provide molecular‐level insight into how ZIF‐90 accommodates and separates gas mixtures, offering design principles for optimizing metal‐organic frameworks in energy and environmental applications.
Journals
2026 EN
Saddique Sadia · Muhammad Shabbir · Bibi Shamsa
+3 more
ABSTRACT The focus of the current work investigation was structural isomerism, caused by variations in atomic connectivity and positional isomerism, resulting in unique molecular geometries and electronic structures that significantly influence the photoelectronic behavior of isomers. This study examines three sets of structural isomers, based on tetracene, pyrene, and chrysene cores, namely PTA‐1 and PTA‐2 , PTA‐3 and PTA‐4 , PTA‐5 and PTA‐6 , respectively. Among all the isomers, PTA‐5 has the best aromatic character, with average HOMA score of 0.749, underscoring that the substitution position holds the key to π‐electron delocalization. The charge transfer character of excited states is examined through Hole–Electron analysis. Among all the investigated systems, PTA‐5 exhibits the highest D ‐index with a value of 0.529 Å, clearly indicating pronounced charge transfer in excited states. A quantum chemical approach utilizing the M06‐2X functional and 6–311G** basis set is employed to examine the optical and nonlinear optical properties. PTA‐1 stands out with a higher α iso value (110.75 × 10 −36 esu), whereas PTA‐3 exhibits the largest <γ> with the value of 486.23 × 10 −36 esu, with the lowest transition energy 3.54 eV. Additionally, a red‐shift absorption peak at 312.7 nm in the UV‐visible spectra of PTA‐5 indicates potential of these compounds in optoelectronic applications.
Journals
2026 EN
Rached Djamel · Elahmar Mohamed Hichem · Caid Messaoud
+5 more
ABSTRACT We report a first‐principles investigation of the structural, mechanical, electronic, and optical properties of the double perovskite hydrides Cs 2 RbAlH 6 and Rb 2 CaNiH 6 . Density functional theory calculations were performed within the GGA‐PBE framework, with an on‐site Hubbard correction applied to Ni‐3d states, using the FP‐LAPW method as implemented in the Wien2k code and plane‐wave calculations in CASTEP. Both compounds are found to crystallize in the cubic Fm‐3m (No. 225) structure and satisfy the mechanical stability criteria, exhibiting brittle behavior according to Pugh's and Poisson's ratios. The calculated hydrogen storage capacities amount to 1.55 and 2.14 wt.% for Cs 2 RbAlH 6 and Rb 2 CaNiH 6 , respectively, with corresponding volumetric densities of 56.16 and 73.36 g H 2 /L, comparable to those reported for related hydride perovskites. Electronic structure calculations indicate that Cs 2 RbAlH 6 is an indirect‐gap semiconductor with a bandgap of 2.35 eV, while Rb 2 CaNiH 6 exhibits an indirect bandgap of 1.10 eV after inclusion of the Hubbard U. The optical response is characterized by pronounced absorption in the ultraviolet region, finite optical conductivity, and distinct plasmonic features. These results establish Cs 2 RbAlH 6 and Rb 2 CaNiH 6 as representative model systems for exploring structure‐property relationships in double perovskite hydrides relevant to hydrogen‐based energy applications.