arXiv subjects

Dilshod Nematov

Publications and source records attributed to Dilshod Nematov.

12 recordsLinked to original sources

arXiv2026

Performance Analysis of Double Perovskite-Based Solar Cells Using SCAPS-1D Simulation: A brief review

Lead-free double perovskites are among the rapidly developing next-generation solar cell technologies, providing the required low toxicity, stability, as well as high optoelectronic potential. So far, experimentally prepared lead-free perovskite solar cell devices are reported to have low power conversion efficiency (PCE) for practical application as compared to the lead-based perovskites. In recent years, numerical simulations have emerged as a cost-effective approach that plays a crucial role in expediting scientific research, can bridge the gap between experiment and theory, and provide predictive information regarding the preparation of solar cells and their PCEs without undergoing real-time experiments. The tools, such as 1D numerical simulation software SCAPS-1D, are now needed to test newer architectures and determine what exactly is holding them back. So far in the field of solar cell research, SCAPS-1D has been extensively used and looks like a powerful software due to its user-friendliness and simulation of results in a few seconds. The speed and ease of simulation make SCAPS-1D a very popular tool; as a result, it enables rapid optimization of a large number of photovoltaic devices and their performances without undergoing any experimental work, which can save time and money. However, one serious drawback is that the SCAPS-1D simulator works only for 1D configurations. It is ineffective in incorporating atomistic interactions and 3D effects. Hence, the efficacy of the SCAPS-1D simulator solely relies on the accuracy of the input parameters that the user provides, failing which may give wrong results and large deviations from accuracy.

cond-mat.mtrl-sci↗

arXiv2026

First-principles Study of Structural and Electronic Properties of Mn-doped Cu2NiXY4 (X=Sn, Ge, Si; Y=S, Se) Chalcogenide Semiconductors

In this work, the effect of partial substitution of Mn by Ni on the structural and electronic properties of kesterite systems Cu2NiXY4 (X = Sn, Ge, Si; Y = S, Se) was studied using density functional theory (DFT). The mBJ+U method was used to characterize the bandgap more accurately. To the best of our knowledge, a systematic comparative study of Mn substitution in the entire Cu2NiXY4 (X = Sn, Ge, Si; Y = S, Se) family has not been previously performed. Due to crystallographic constraints of the kesterite unit cell, the substitution of a single Ni atom with Mn corresponds to 50%. This configuration was chosen to study the effect of Mn substitution on the structural and electronic properties of Cu2NiXY4 (X = Sn, Ge, Si; Y = S, Se) compounds, whereas the study of lower concentrations requires the use of a supercell and is the subject of further research. The calculation results show that the partial substitution of Ni with Mn preserves the tetragonal structure of kesterite and significantly alters the electronic structure. In all the compounds studied, the bandgap decreases from 1.028-3.397 to 1.007-3.333 eV. For example, in the Cu2NiSnS4 system, the bandgap width decreases from 1.59 eV to 1.49 eV. The narrowing of the bandgap results from hybridization between the Mn-3d, Cu-3d, and S/Se-p orbitals near the band edges, leading to a redistribution of electronic states around the Fermi level. The results demonstrate that Mn substitution is an effective strategy for controlling the electronic properties of Cu2NiXY4 kesterites, offering great promise for use in optoelectronic devices where adjustable bandgaps are required.

cond-mat.mtrl-sci↗

arXiv2026

Optoelectronic and Thermoelectric Properties of High-Performance AlSb Semiconductors

This study presents a comprehensive first-principles investigation of the optoelectronic and thermoelectric properties of aluminum antimonide (AlSb) in its cubic (F-43m) and hexagonal (P63mc) phases. Structural optimization was performed using the SCAN functional, and all electronic and optical properties were evaluated using the modified Becke-Johnson potential combined with the Hubbard correction (mBJ+U), which best describes the band-edge electronic structure, explicitly accounting for the contribution of the d-states of the Sb half-core, which cannot be adequately accounted for by conventional functionals and may be overestimated by hybrid approaches. Both AlSb phases are found to be quasi-direct bandgap semiconductors, with calculated band gaps of 1.71 eV for the cubic phase and 1.50 eV for the hexagonal phase, in good agreement with available experimental data. The optical response reveals strong absorption in the visible and ultraviolet regions, moderate reflectivity, and high refractive indices, indicating pronounced light-matter interaction characteristic of III-V semiconductors. The hexagonal phase exhibits enhanced low-energy optical absorption due to its reduced symmetry and narrower band gap. Thermoelectric analysis demonstrates large negative Seebeck coefficients, thermally activated carrier generation, and a monotonic increase of the power factor with carrier concentration for both phases. The cubic phase shows higher power factor values due to enhanced carrier mobility, whereas the hexagonal phase benefits from reduced thermal conductivity, which is favorable for thermoelectric performance at elevated temperatures. These results establish AlSb as a multifunctional semiconductor with tunable optoelectronic and thermoelectric properties and highlight the importance of an accurate treatment of Sb d-electron effects for reliable property prediction.

cond-mat.mtrl-sci↗

arXiv2026

SAM Molecular Stacking with Heterogeneous Orientationfor High-Performance Perovskite Photovoltaics

This study demonstrates that thermal-evaporated SAM (eSAM) films, particularly in a thick configuration, spontaneously adopt a heterogeneous molecular orientation, forming a vertical-to-horizontal gradient in molecular packing. This unique architecture establishes a graded energy barrier, which is shown to facilitate more efficient hole transport compared with the single energy barrier presented by conventional thin SAMs. In conclusion, while solution-processed SAMs present formidable scalability challenges, the thermal evaporation of SAMs offers a viable pathway toward industrial-scale fabrication. The strategy of employing thick eSAM films with gradient molecular packing not only circumvents the uniformity issues of solution methods but also introduces a superior structure for charge transport, positioning it as a promising enabler for the commercialization of high-efficiency perovskite photovoltaics. The inability to achieve uniform hole transport with solution-processed self-assembled monolayers (SAMs) constitutes a fundamental bottleneck for scaling perovskite photovoltaics. Herein, we demonstrate that thermal-evaporated SAMs (eSAMs) overcome this limitation by enabling precise thickness control. Crucially, a thickened eSAM spontaneously forms a vertical-to-horizontal gradient in molecular orientation, which creates a descending energy barrier that directionally facilitates hole transport. This tailored interface also ensures excellent surface coverage and directs the growth of high-quality perovskite films. Consequently, the resultant photovoltaic devices set new benchmarks, delivering impressive power conversion efficiencies (PCEs) of 21.46% (small-area, 0.108 cm2) and 19.38% (large-area module, 15.52 cm2) for fully vacuum-evaporated devices, while also setting an impressive PCE of 23.67% for eSAM-based devices with solution-processed perovskites.

cond-mat.mtrl-sci↗

arXiv2026

A high-performance cobalt-free cathode for proton-conducting solid oxide fuel cells via multi-element doping in Sr2Fe2O6

The development of efficient and stable intermediate-temperature solid oxide fuel cells (SOFCs) necessitates high-performance cathode materials that are cobalt-free, cost-effective, and compatible with proton-conducting electrolytes. While Sr2Fe2O6 (SFO)-based ferrites offer a promising cobalt-free alternative, their electrochemical performance requires further enhancement to compete with state-of-the-art cathodes. This study proposes and validates a multi-element doping strategy as a superior approach to tailor the properties of SFO. The specific oxide Sr2Fe1.5Mo0.125Sn0.125Sc0.125Zr0.125O6 (SFO-ZSSM) is designed, synthesized via a solid-state reaction method, and systematically evaluated as a cathode for proton-conducting SOFCs (H-SOFCs). Its performance is benchmarked against a series of SFO cathodes modified with single dopants (Mo, Sn, Sc, Zr). Structural characterization confirms the successful formation of a phase-pure perovskite structure with homogeneous elemental distribution. Electrical conductivity relaxation (ECR) measurements reveal that SFO-ZSSM exhibits dramatically enhanced oxygen and proton transport kinetics compared to all singly-doped counterparts, demonstrating a significant synergistic effect. Consequently, fuel cells employing the SFO-ZSSM cathode deliver exceptional peak power densities of 1580, 1137, and 854 mW cm-2 at 700, 650, and 600 {\deg}C, respectively, significantly outperforming cells with single-doped cathodes. Electrochemical impedance spectroscopy further corroborates its superior catalytic activity, showing the lowest polarization resistance. Moreover, the SFO-ZSSM cell demonstrates excellent operational stability over 100 hours, attributed to its robust microstructure and Ba-free composition.

cond-mat.mtrl-sci↗

arXiv2026

A brief review of high-entropy oxides in solid oxide fuel cell applications

Solid oxide fuel cells are efficient energy conversion devices essential to clean energy development, yet their broad application is limited by material challenges, including sluggish oxygen reduction kinetics at intermediate temperatures, electrode instability and vulnerability to contaminants. High-entropy oxides, a novel class of materials characterized by multiple principal elements and high configurational entropy, present a promising approach to overcome these issues via their distinctive "four core effects". This review begins with the fundamentals of high-entropy materials, covering their definition, phase stabilization mechanisms, and relevant descriptors, then systematically reviews their progress as SOFC cathodes, electrolytes, and anodes. Key advances are summarized, and current challenges are analyzed, offering guidance for the design of high-performance and stable high-entropy oxides for solid oxide fuel cells.

cond-mat.mtrl-sci↗

arXiv2026

Tuning Optoelectronic Properties and Photoelectrochemical Performance of \b{eta}-TaON via Vanadium Doping

The application of beta-TaON for solar-driven water splitting is hindered by limitations in phase purity, stoichiometry, crystallinity, visible-light absorption, carrier mobility, and high recombination rates. This study investigates the impact of vanadium doping (0-25 at.% V) on the structural, optoelectronic, and photoelectrochemical properties of beta-TaON using both experimental and density functional theory (DFT) approaches. Phase-pure beta-TaON is retained up to 10 at.% V, beyond which secondary phases (Ta2O5 and VN) form, indicating a threshold of ~10 at.% under the applied synthesis conditions. All samples exhibit a porous microstructure. Increasing vanadium content induces a redshift in the absorption edge, reducing the bandgap from 2.72 eV (undoped) to 2.38 eV at 25 at.% V for the main beta-TaON phase, in agreement with DFT results. X-ray photoelectron spectroscopy confirms substitutional incorporation of V5+ for Ta5+ in the beta-TaON lattice. DFT calculations reveal reduced electron effective mass, enhanced n-type conductivity, and favorable band edge shifts enabling spontaneous overall water splitting at <=10 at.% V. Photoelectrochemical measurements show improved photocurrent and more negative onset potentials for 5-10 at.% V, while higher V doping degrades performance due to phase segregation, which likely increases recombination and hinders interfacial charge transport. Vanadium doping (<=10 at.% V) is an effective strategy for tuning the electronic structure and enhancing the optical properties and photoelectrochemical performance of beta-TaON.

cond-mat.mtrl-sci↗

arXiv2026

Molecular Adsorption of H2O on TiO2 and TiO2:Y Surfaces

In this work, using theoretical calculations within the framework of the density functional theory, taking into account the dispersive VDW interaction, the processes of adsorption and interaction of a water molecule with a TiO2 surface in various configurations are investigated. At the atomic/molecular level, the interactions of a water molecule with a TiO2 surface have been studied for various orientations. The results of calculations within the framework of DFT+ VDW show that the adsorption energies of single water molecules in different initial positions on the substrate surface vary from-0.72 to-0.84 eV, and the most stable adsorbate structure is the TiO2+ H2O system upon adsorption of a molecule of water, parallel to the Y axis, because during the adsorption of H2O parallel to the Y axis, some favorable effects are observed in the band structure of titanium dioxide. On the one hand, the band gap decreases to 2.59 eV, and on the other hand, a new energy state appears in the band gap with an energy contribution of 0.17 eV, when water is physisorbed and interacts with a titanium atom at a distance of 2.12 {\AA} and occupies a perpendicular position relative to the surface.

cond-mat.mtrl-sci↗

arXiv2026

Analysis of the Optical Properties and Electronic Structure of Semiconductors of the Cu2NiXS4 (X = Si, Ge, Sn) Family as New Promising Materials for Optoelectronic Devices

In this work, the optoelectronic characteristics of kesterites of the Cu2NiXS4 system (X = Si, Ge, Sn) were studied. The electronic properties of the Cu2NiXS4 (X = Si, Ge, Sn) system were studied using first-principles calculations within the framework of density functional theory. For calculations, ab initio codes VASP and Wien2k were used. The high-precision modified Beke-Jones (mBJ) functional and the hybrid HSE06 functional were used to estimate the bandgap, electronic and optical properties. Calculations have shown that when replacing Si with Ge and Sn, the band gap decreases from 2.58 eV to 1.33 eV. Replacing Si with Ge and Sn reduces the overall density of electronic states. In addition, new deep (shallow) states are formed in the band gap of these crystals, which is confirmed by the behavior of their optical properties. The obtained band gap values are compared with existing experimental measurements, demonstrating good agreement between HSE06 calculations and experimental data. The nature of changes in the dielectric constant, absorption capacity and optical conductivity of these systems depending on the photon energy has also been studied. The statistical dielectric constant and refractive index of these materials were found. The results will help increase the amount of information about the properties of the materials under study and will allow the use of these compounds in a wider range of optoelectronic devices, in particular, in solar cells and other devices that use solar radiation to generate electric current.

cond-mat.mtrl-sci↗

arXiv2025

Thermodynamic Phase Stability, Structural, Mechanical, Optoelectronic, and Thermoelectric Properties of the III-V Semiconductor AlSb for Energy Conversion Applications

This study presents a first principles investigation of the structural, thermodynamic, electronic, optical and thermoelectric properties of aluminum antimonide (AlSb) in its cubic (F-43m) and hexagonal (P63mc) phases. Both structures are dynamically and mechanically stable, as confirmed by phonon calculations and the Born Huang criteria. The lattice constants obtained using the SCAN and PBEsol functionals show good agreement with experimental data. The cubic phase exhibits a direct band gap of 1.66 to 1.78 eV, while the hexagonal phase shows a band gap of 1.48 to 1.59 eV, as confirmed by mBJ and HSE06 calculations. Under external pressure, the band gap decreases in the cubic phase and increases in the hexagonal phase due to different s p orbital hybridization mechanisms. The optical absorption coefficient reaches 1e6 cm-1, which is comparable to or higher than values reported for other III V semiconductors. The Seebeck coefficient exceeds 1500 microV per K under intrinsic conditions, and the thermoelectric performance improves above 600 K due to enhanced phonon scattering and lattice anharmonicity. The calculated formation energies (-1.316 eV for F-43m and -1.258 eV for P63mc) confirm that the cubic phase is thermodynamically more stable. The hexagonal phase exhibits higher anisotropy and lower lattice stiffness, which is favorable for thermoelectric applications. These results demonstrate the strong interplay between crystal symmetry, phonon behavior and charge transport, and provide useful guidance for the design of AlSb based materials for optoelectronic and energy conversion technologies.

cond-mat.mtrl-sci↗

arXiv2025

A Review on Improving PSC Performance through Charge Carrier Management: Where We Stand and What's Next?

Perovskite solar cells (PSCs) represent a breakthrough in photovoltaic technology, combining high power conversion efficiencies (PCEs), ease of fabrication, and tunable optoelectronic properties. However, their commercial viability is limited by critical issues such as charge carrier recombination, interfacial defects, instability under environmental stress, and toxicity of lead-based components. This review systematically examines recent advancements in charge carrier management strategies aimed at overcoming these limitations. Initially, fundamental mechanisms governing carrier generation, separation, transport, and recombination are outlined to provide a clear foundation. The study then delves into an in-depth analysis of carrier lifetime and mobility, evaluating recent methodologies for their enhancement through compositional engineering and structural optimization. Subsequently, trap state passivation techniques and interface engineering approaches are reviewed, with a particular focus on their impact on device stability and efficiency. The review also discusses long-term stability strategies and emerging trends in lead-free and scalable PSC technologies. In this work, recent strategies for charge carrier management are systematically categorized, comparative analyses are provided and synergistic solutions with high potential for real-world implementation are highlighted. By synthesizing data and perspectives from over thirty recent studies, this article offers a comprehensive roadmap for researchers seeking to optimize PSC performance and accelerate their transition toward commercial application.

cond-mat.mtrl-sci↗

arXiv2025

Machine Learning - Driven Materials Discovery: Unlocking Next-Generation Functional Materials - A review

The rapid advancement of machine learning and artificial intelligence (AI)-driven techniques is revolutionizing materials discovery, property prediction, and material design by minimizing human intervention and accelerating scientific progress. This review provides a comprehensive overview of smart, machine learning (ML)-driven approaches, emphasizing their role in predicting material properties, discovering novel compounds, and optimizing material structures. Key methodologies in this field include deep learning, graph neural networks, Bayesian optimization, and automated generative models (GANs, VAEs). These approaches enable the autonomous design of materials with tailored functionalities. By leveraging AutoML frameworks (AutoGluon, TPOT, and H2O.ai), researchers can automate the model selection, hyperparameter tuning, and feature engineering, significantly improving the efficiency of materials informatics. Furthermore, the integration of AI-driven robotic laboratories and high-throughput computing has established a fully automated pipeline for rapid synthesis and experimental validation, drastically reducing the time and cost of material discovery. This review highlights real-world applications of automated ML-driven approaches in predicting mechanical, thermal, electrical, and optical properties of materials, demonstrating successful cases in superconductors, catalysts, photovoltaics, and energy storage systems. We also address key challenges, such as data quality, interpretability, and the integration of AutoML with quantum computing, which are essential for future advancements. Ultimately, combining AI with automated experimentation and computational modeling is transforming the way materials are discovered and optimized. This synergy paves the way for new innovations in energy, electronics, and nanotechnology.

cond-mat.mtrl-sci↗