The steady rise in atmospheric CO2 levels has led to a serious environmental threat in the form of global warming and climate change. Therefore, the development of efficient porous nanomaterials as adsorbent and catalyst that simultaneously capture CO2 and catalytically convert it into value-added chemicals is a very challenging area of research today. Herein, we report the synthesis of three nitrogen-rich, aminal-linked porous organic polymers (POPs), namely, TBAL-POP-3, TBAL-POP-4, and TBAL-POP-5, constructed via extended Schiff-base condensation reaction under solvothermal conditions. Among the three polymers, TBAL-POP-5 exhibits the highest specific surface area (1053 m2 g−1), highest fraction of hierarchical mesopores (84%), and high CO2 uptake capacity of 1.92 mmol g−1 at 273 K and 1 bar and good CO2/N2 selectivity 43.82/32.03 at 273/298 K. The enhanced gas adsorption performance of TBAL-POP-5 is attributed to its mesopore-enriched hierarchical structure, which facilitates efficient mass transfer and active site accessibility. Furthermore, these materials demonstrated good catalytic activity toward the formylation of amines using CO2 as a sustainable C1 source in the presence of dimethylamine borane as a green reducing agent. This work highlights the dual functionality of nitrogen-rich porous polymers as multifunctional platforms for integrated CO2 capture and its reductive valorization.

Zero-dimensional cesium lead halide (Cs4PbBr6) perovskites are distinguished by their structural robustness and defect-mediated optical properties, yet the origin of their emissive behavior remains elusive. Here, we reveal a hierarchical defect architecture in Cs4PbBr6 microcrystals, wherein embedded CsPbBr3 inclusions hosting bromine vacancies (VBr), form multilevel CsPbBr3-VBr coupling states that govern charge-carrier dynamics. A micro-solvent–assisted mechanochemical strategy employing trace DMSO solvent enabled precise defect modulation while achieving low process mass intensity (PMI ∼5, far below conventional solution routes, ∼180) and structural fidelity. Comparative analyses of dry-synthesized (D-Cs4PbBr6), DMSO-assisted (B-Cs4PbBr6), and ligand-mediated (L-Cs4PbBr6) microcrystals reveals the presence of hierarchical defect states are confirmed by low-temperature photoluminescence, cathodoluminescence, and transient absorption spectroscopy, with DFT calculations identifying mid-gap states (∼1.93 eV) responsible for NIR-range emission. While shallow states drive this emission, detrimental deep traps are effectively neutralized by sulfate-ion passivation, extending carrier lifetimes from 35.48 to 41.43 ns and enabling suppression in photoluminescence quenching. The optimized bromine-vacancy densities facilitate enhanced CO2 photoreduction (70.21 µmol g−1 h−1, apparent quantum yield 1.42%), nearly 1.6× higher than defect-free analogues, consistent with DFT-predicted shallow VBr states enhancing charge availability. These findings establish a scalable, defect-engineered mechanochemical route for multifunctional perovskites, uniting robust luminescence and efficient photocatalytic energy conversion.

Urea, a strategic material, is synthesized electrochemically by utilizing two of the major air and water pollutants, carbon dioxide (CO2) and nitrate (NO3–), respectively, as feedstocks. A Boron (B, c.a. 1.6 wt %) and Nitrogen (N, c.a. 39.5 wt %) enriched nanoporous Polymeric Material, BNPM, synthesized by a fast microwave-assisted method using melamine and benzeneboronic acid, has been used as an efficient electrocatalyst for urea production. Optimized textural properties (specific surface area, SABET of 600 m2 g–1) along with simultaneous enrichment of B and N synergistically led to high catalytic performance, which could be attributed to favorable interactions of NO3– and CO2 molecules with the electrocatalyst. BNPM achieved a high Faradaic Efficiency (FE) of 53.2% with a urea yield rate of 31.0 μg h–1 mg–1 at −0.7 V (vs RHE) in 0.1 M KNO3 solution saturated with CO2. Another strategic material, ammonia, was also formed with an FE of 18.5%; however, at a potential of −0.6 V (vs RHE), keeping all other experimental conditions identical, ammonia was the predominant product with an FE of 39.4% and a corresponding yield rate of 6.0 μg h–1 mg–1. A chronoamperometry test for 12 h indicates stable electrocatalytic activity. A combination of in situ Raman spectroscopy coupled with density functional theory (DFT) validated the formation of various reaction intermediates leading to product formation, while the latter provided information on the role of B and N for effective C–N coupling.

As perovskite solar cells near commercialization, concerns about organic and toxic components remain. Inorganic CsSnX3 (X = I, Cl) emerges as a promising alternative due to its eco-friendliness, high carrier mobility, and stability, with a bandgap ranging from 1.3 to 1.55 eV. However, issues such as high carrier concentration, band misalignment, and material defects still exist. This study uses the Vienna Ab initio Simulation Package (VASP) to analyze the crystal and optoelectronic properties of CsSnI3 and CsSnCl3. Both exhibit direct bandgaps of 1.33 and 1.52 eV, respectively, and strong UV–visible absorption (∼105 cm−1), indicating their potential in solar applications. Using one dimensional solar cell capacitance simulator (SCAPS-1D), a novel solar cell structure is designed to harness both sub-bandgap and above-bandgap photons. A low-bandgap absorber is embedded within a high-bandgap layer, forming a straddling-type sandwiched structure. This configuration creates a confined region with a proper conduction band offset, while the surrounding p+/n+ layers generate a strong internal electric field. Key parameters like position, thickness, and barrier height are optimized for carrier transport and minimal recombination. The simulation predicts a theoretical efficiency of ∼34%, indicating the potential of the proposed device architecture to guide future experimental efforts toward realizing enhanced photovoltaic performance.

NiFe-based MIL-55 metal-organic frameworks (MOFs) face challenges in achieving atomically precise composition and reliable methods for uniform growth. This study addresses these challenges by applying a slow evaporation crystallization technique to crude colloidal MIL-55 products from hydrothermal synthesis, resulting in highly uniform, hexagonal pyramid-shaped NiFe-MIL-55 nanorods (NRs). In contrast, isolating MIL-55 through antisolvent precipitation leads to irregular shapes, highlighting the critical role of the crystallization method. This shape control enables single-particle analysis, revealing tunable atomic compositions ranging from Ni1Fe9 to Ni9Fe1 by adjusting the Ni2+/Fe3+ precursor ratios. A volcano-type morphology plot illustrates the role of the Ni-BDC framework in shape control, where Ni4Fe6 to Ni8Fe2 compositions produce uniform NRs, whereas others yield mixed or irregular morphologies. The electrocatalytic oxygen evolution reaction (OER) and supercapacitor performances of these NRs were evaluated, with Ni7Fe3-MIL-55 showing the best OER performance, including a low overpotential of 230 mV at 10 mA cm−2 and a Tafel slope of 64 mV dec−1. It also demonstrates excellent stability, retaining 82% of its OER activity over 50 h, as well as superior supercapacitor performance (571 F g−1 at 1 A g−1), making it a promising dual-function material. Density functional theory (DFT) calculations reveal that Ni7Fe3 has the lowest limiting potential (0.52 V) compared to its single-metal counterparts, explaining its enhanced OER activity. This work provides a strategy for atomically precise MOF nanostructure design, offering valuable insights into electrocatalytic behavior and guiding the development of materials for renewable-energy technologies.

Lead-free double perovskites (LFDPs), as environmentally sustainable alternatives to lead-based perovskites, have attracted growing attention for a wide range of optoelectronic applications. Among various strategies, doping has emerged as a powerful approach to tune and enhance their optical properties. However, realizing their practical potential requires a comprehensive understanding of their photophysical behavior. Here, we investigate Bi3+/Ho3+ co-doped Cs2AgInCl6 nanocrystals, comprising 1% Bi3+ and variable Ho3+ content (referred to as Ho3+-doped CABIC), which are direct-bandgap double perovskite nanocrystals (DPNCs). These nanocrystals exhibit dual visible and near-infrared (NIR) emission, combined with excellent thermal and moisture stability. Efficient energy transfer from self-trapped excitons (STEs) in the host lattice to Ho3+ ions plays a central role in enabling strong dual visible–NIR emission. Femtosecond transient absorption spectroscopy revealed a transfer time of 95 ps, highlighting a fast and effective sensitization pathway. Notably, in this efficiently luminescent sample, THz spectroscopy revealed reduced photoconductivity and carrier mobility, attributed to a higher effective mass and the presence of Ho 4f states near the conduction band minimum, as supported by DFT calculations. Beyond fundamental insights, the multifunctionality of Ho3+-doped CABIC is demonstrated through its application in optical thermometry and phosphor-converted light-emitting diodes (pc-LEDs). A maximum relative temperature sensitivity of 0.76% K−1 is achieved, outperforming many conventional thermometric materials. Furthermore, the fabricated pc-LED exhibited warm orange-yellow light with CIE coordinates of (0.48, 0.46) together with efficient NIR emission. These findings position Ho3+-doped CABIC nanocrystals as promising candidates for next-generation eco-friendly lighting and photonic technologies.

Thulium ions (Tm3+) are employed to expand the luminescent properties of metal halide perovskites due to their rich array of long-wavelength near-infrared (NIR) luminescent energy levels. However, Tm3+ still exhibits weak emission in double perovskites (DPs) owing to the parity-forbidden nature of its f–f transitions, leading to poor absorption. In this study, the rare-earth-based DP Cs2NaTmCl6 was successfully synthesized via a facile method. This material exhibits self-sensitized NIR-I and NIR-II emission under its characteristic excitation. Upon introducing Sb3+ ions, which possess strong absorption in the UV region, the NIR photoluminescence external quantum efficiency (EQE) of Cs2NaTmCl6:3% Sb3+ reaches 21.6%. This enhancement is attributed to the presence of the 1G4 energy level of Tm3+, which acts as a bridge to efficiently transfer energy from the high-energy states of Sb3+ to the NIR-emitting states of Tm3+. Both the pristine and Sb3+-doped Cs2NaTmCl6 demonstrate excellent thermal quenching resistance. Through a combined experimental and theoretical approach, we demonstrate that the incorporation of Sb3+ ions reduces the effective optical bandgap of the host matrix by providing additional absorption channels. Leveraging the efficient NIR luminescence, we designed an NIR night-vision illumination and imaging system. Furthermore, exploiting the emergence of visible luminescence and the distinct NIR emission intensities before and after Sb3+ doping, we developed a dual-mode optical anti-counterfeiting label. These findings provide novel design insights and inspiration for achieving NIR luminescence in rare-earth-based DPs.

The size, functionality and orientation of organic spacer cations in low dimensional perovskites strongly influence their optoelectronic properties. The effect of spacer cation isomerism leads to the formation of distinct ordered perovskites with well-defined structure–property relationships. In this work, the influence of organic spacer isomers—phenylene diammonium (PDA) cations, namely (o-PDA)2Bi2I10, (m-PDA)2Bi2I10, and (p-PDA)2Bi2I10·6H2O, on the optoelectronic behavior of the perovskite-like hybrid organic bismuth halide PDA2Bi2I10 is systematically investigated. Structural and electronic variations arising from isomerism are examined using X-ray diffraction, UV-visible absorption spectroscopy, and photoelectron spectroscopy, with further validation provided by density functional theory (DFT) calculations. The PDA cation enables the formation of edge sharing [Bi2I10]4− dimers, placed close to each other with the I–I distance between adjacent dimers well within the covalent bond requirements. Octahedral dimers are separated by PDA cations, wherein the ortho position of the substituent in the spacer cation induces higher strain. Both functional groups interact with the same dimer, causing higher angle distortions and density of states resulting in delocalized electron wavefunctions. The extra advantage of the N contribution to the same dimer in OPDA is that it favours higher absorption and conduction, strongly influencing the optoelectronic properties. Revealing such structure property relationships where weak yet cooperative interactions can still yield macroscopic differences in performance can provide a guide for the design of such low dimensional hybrid organic bismuth halides with desirable properties for functional devices.

While morphological control in metal–organic frameworks (MOFs) has been widely explored, the extension of this concept to compositional engineering and precise anisotropic growth in high-entropy systems has only recently emerged. Herein, we present the first synthesis of one-dimensional single-crystal HE-MOF-74 nanorods (comprising Co, Fe, Ni, Zn, and Mo) via a dual strategy, where zinc-directed anisotropic growth occurs exclusively on a graphene oxide support. In situ Raman spectroscopy combined with molecular probe electroanalysis and DFT analysis reveal two simultaneous catalytic pathways. (i) The oxophilic Mo promotes the adsorbate evolution mechanism (AEM) with Ni centers (Ni–Ni*-Mo), (ii) Zn enhances the covalency of the M–O bonds, specifically favoring Fe–O/Co–O covalency to activate the lattice-oxygen-mediated mechanism (Co/Fe–O*-Zn). This synergistic dual-pathway mechanism in the HE-MOF nanorod is directly responsible for the exceptional electrocatalytic performance, which includes an ultralow OER overpotential of 220 mV and remarkable stability sustained for 250 h at a high current density of 100 mA cm–2. It also demonstrates superior performance for urea (UOR, 1.32 V at 10 mA cm–2), ethanol (EOR, 1.31 V at 10 mA cm–2), and methanol (MOR, 1.355 V at 10 mA cm–2) oxidation reactions, significantly outperforming its lower-entropy counterparts. This work demonstrates how Zn ions, supported by graphene oxide, play a crucial role in directing anisotropic growth in high-entropy systems, while simultaneously activating dual-mechanistic pathways to synergistically enhance multianodic reactions.

Efficient bifunctional catalysts for the OER and ORR are vital for clean energy, but the best-known catalysts (Pt and Ir) are scarce and expensive. Nonprecious materials such as heteroatom-doped graphene (sp2-carbon) show promise due to high conductivity and stability, but exhaustively screening their many configurations via density functional theory (DFT) is prohibitive. To address this, we developed Padarth Khoj, a machine learning-powered GUI for catalyst screening. The GUI ingests DFT outputs (e.g., DOSCAR/CONTCAR), computes electronic descriptors (such as π-orbital occupancy and density of states of π-orbital at Fermi level), and uses SVR/MLR models to predict adsorption energies ΔGOH and ΔGO – ΔGOH. The trained SVR model achieved high accuracy (R2 ≈ 0.85–0.89 for the OER/ORR). The interface supports batch analysis and visualization, streamlining workflow. Using only 160 initial DFT calculations, Padarth Khoj predicted overpotentials for ∼8000 active sites (vs ∼24,080 by brute-force DFT). The tool identified 31 catalysts with predicted bifunctional activity, and DFT validation on 10 of these confirmed ∼85% of the predictions. This corresponds to a reduction in computational effort and time by several orders of magnitude, which allows one to explore very large catalyst spaces. Overall, this ML-driven pipeline drastically reduces the screening effort and supplies physical insights to aid the rational design of low-cost OER/ORR electrocatalysts for sustainable energy technologies.

Molecular electrocatalysis is commonly interpreted through electronic descriptors, implicitly treating catalysts as mechanically passive during redox cycling. Yet, electron transfer often imposes structural demands on molecular scaffolds, raising the question of whether internal mechanical constraints can directly regulate access to reactive states and, in turn, catalytic outcomes. Addressing this question has remained challenging because mechanical effects are typically inseparable from changes in composition or electronic structure. Here, we achieve this separation by exploiting two constitutionally identical molecular catalysts whose only distinction is ligand geometry. This minimal geometric variation enables or suppresses intramolecular hydrogen bonding, thereby encoding distinct mechanical constraints that isolate molecular mechanics as a variable in redox accessibility. In the α isomer, molecular constraints impose a mechanically enforced barrier that severely limits access to the reactive redox state. This disrupts the temporal ordering of elementary steps, and diverts reactivity toward competing hydrogen evolution, eroding both selectivity and stability. In contrast, mechanical compliance in the β isomer enables facile access to the redox-active state, allowing CO2 activation to intrinsically outpace water activation and yielding CO selectivities exceeding 92%. Operando spectroscopy and real-time mass spectrometry, combined with computational simulation, directly resolve this mechanically gated reaction sequence as it unfolds. Molecular mechanics thus emerge as determinants that link electron flow to reaction sequencing and catalytic selectivity, revealing that constitutionally similar catalysts can be mechanically, and therefore catalytically, distinct.

Transition-metal-substituted manganese ferrites, Mn0.95M0.05Fe2O4 (M: Co, Cu, and Zn), with a single-phase cubic spinel structure, were synthesized using the combustion method. A high specific surface area (SABET) of 107 m2 g−1, along with pore size distribution (1.7 and 3.4 nm), was obtained for Mn0.95Zn0.05Fe2O4. All the synthesized ferrites exhibited significant hydrazine oxidation (HzOR) activity, and mass‑loading optimization revealed that their performance correlated with increasing SABET in the following order: Mn0.95Zn0.05Fe2O4 > Mn0.95Co0.05Fe2O4 > Mn0.95Cu0.05Fe2O4 > MnFe2O4. Importantly, Mn0.95Zn0.05Fe2O4 demonstrated fast kinetics for HzOR with a low Tafel slope of 193 mV dec−1 and an electron transfer coefficient of 0.31. Further, it delivers a high current density of 115 mA cm−2 with mass loading of 0.96 mg for HzOR. The Mn0.95Zn0.05Fe2O4 electrocatalyst exhibits the lowest onset potential of 0.65 V vs. RHE compared to other synthesized electrocatalysts. The double-layer capacitance (Cdl) of 0.49 mF cm−2 corroborates a higher SABET and porous microstructure of Mn0.95Zn0.05Fe2O4. DFT study reveals that the potential‑determining step (*N2H3 → *N2H2) has the lowest free‑energy barrier with a low limiting potential of 0.19 V for Mn0.95Zn0.05Fe2O4. The low barrier arises from Zn substitution, which moderates N2H3 adsorption, stabilizes intermediates, and enhances HzOR activity.

Indoor photovoltaic (IPV) cells are designed to operate under low-intensity artificial light sources. Generally, artificial light sources have a narrow spectrum, which can be efficiently captured by a wide band gap absorber. However, existing wide band gap absorbers, such as amorphous silicon (a-Si), perovskite (MAPbX3), suffer from toxicity and stability issues, making it essential to explore an alternative that is an earth-abundant, environmentally friendly. In this study, we used Vienna ab initio Simulation Package (VASP)-based ab-initio calculations to investigate Cu2BaSnS4 (CBTS) materials, focusing on their crystal structure, optoelectronic properties, and performed SCAPS-based simulations for performance estimation. CBTS exhibits a direct band gap ( E g ) of ∼1.9 eV and high absorption coefficient (α ∼ 105 cm−1) in the UV-visible spectrum, making it ideal for IPV applications. Detailed balance calculations predict remarkable solar cell efficiencies of 59.96% ( E g = 1.9 eV) and 57.51% ( E g = 1.95 eV) under indoor light emitting diode (LED) and compact fluorescent light (CFL) lighting. The simulated efficiency exceeding 50% are attributed to the narrow emission spectrum of indoor light sources, which is efficiently absorbed by wide band gap CBTS. Key factors influencing efficiency include high shunt resistance (RSh > 106 Ω cm2) and minimal impact of series resistance up to 100 Ω cm2. A key distinction between IPV and outdoor photovoltaics is the lower photo-generated carrier concentration in low-light conditions, leading to a higher ratio of trapped to photo-generated carriers. These findings highlight CBTS’s potential for next-generation indoor energy solutions.

The recent year has witnessed a flurry of activities in investigating the promising electronic, optical, and transport properties of lead-free double perovskite halides. In the present work, the structural, electronic, optical, and transport properties of Cs2(Li/Na)GaI6 are carefully examined. The predicted negative formation energy, absence of imaginary frequency in the phonon spectra, and ab-initio molecular dynamics calculations show that they are thermodynamically stable. Additionally, electronic studies employing generalized gradient approximation (GGA)–Perdew–Burke–Ernzerhof (PBE) + modified Becke-Johnson + spin-orbit coupling reveal that Cs2(Li/Na)GaI6 exhibits a direct bandgap, with values of 1.24 eV for Cs2LiGaI6 and 1.39 eV for Cs2NaGaI6. The exceptional optical properties, including a high absorption coefficient (105 cm−1) and excellent optical conductivity with low reflectivity across the entire UV–visible range, indicate that Cs2(Li/Na)GaI6 are promising materials for solar cell applications. Moreover, the ultralow thermal conductivity, high Seebeck coefficient, and substantial electrical conductivity of Cs2(Li/Na)GaI6 result in a high figure of merit over the temperature range of 200–600 K. Thus, Cs2(Li/Na)GaI6 shows strong potential as both photovoltaic and thermoelectric materials.

Enhancing the efficiency of solar cells depends on minimizing reflection losses to boost photon absorption. In this study, we investigated the chemical etching process of pristine InP(100), (named as pris-InP(100)). Our findings demonstrate that the etching process resulted in a self-organizing V-groove microstructure, as revealed by atomic force microscopy and scanning electron microscopy. This induced V-groove microstructure resulted a significant reduction in the reflection loss. Through temporal variation in the etching process, we identified that a 5-minute etch (named as etch5-InP(100)), yielded the lowest reflectance. Additionally, radiofrequency (RF) magnetron sputtering was employed to deposit a 10 nm Nb2O5 thin film on both pris-InP (100) and etch5-InP (100) samples. The results indicated that the thin film on etch5-InP(100) exhibited significantly lower reflectance compared to pris-InP(100). Moreover, ab-initio calculations verified the stability and presence of native oxide at the interface of the Nb2O5/InP(100) heterostructure. Furthermore, dark current-voltage (I-V) characteristics indicated typical diode behaviour for both Nb2O5 thin films deposited on pris-InP(100) and etch5-InP(100). Notably, light I-V measurements revealed that the Nb2O5 thin film on etch5-InP(100) achieved a higher efficiency of 11.6 % compared to the 8.7 % efficiency of pris-InP(100). This study provides valuable insights and guidelines for the development of high-efficiency InP-based solar cells.

In this article, we embark on an exciting journey to identify the ideal electron transport layers (ETL) and hole transport layers (HTL) that can significantly boost the efficiency of CsPbI2Br-based solar cells. Utilizing first-principles calculations with the modified Becke-Johnson potential (mBJ) and spin-orbit correction, we uncovered the direct band gap property of CsPbI2Br, measuring an impressive 1.81 eV. Coupled with its remarkable absorption coefficient of 105 cm⁻1 and minimal reflectivity throughout the visible spectrum, this material stands out as an emerging absorber layer for photovoltaic cells. Also, using cutting-edge SCAPS-1D simulations, we explore a range of ETL materials, including TiO2, ZnO, CdS, STO, WS2, and Nb2O5, alongside HTL options like NiO, Spiro, SnS, CuI, Cu2O, and CuSbS2. Our findings reveal that Nb2O5 and Cu2O emerge as the most promising candidates for ETL and HTL to enhance the performance of CsPbI2Br absorbers, opening the door to more efficient solar energy solutions. The efficiencies achieved with the ETL and HTL-based solar cells, specifically Au/CsPbI2Br/Nb2O5/FTO and Au/Cu2O/CsPbI2Br/FTO, are impressive, standing at 17.91 % and 18.13 %, respectively. Moreover, various factors such as the thickness of the absorbing layer, HTL, and ETL, along with total defect density (Nt), donor and acceptor defect densities of both the absorber and the transport layers, and the device temperature, significantly influence the performance metrics of the Au/Cu2O/CsPbI2Br/Nb2O5/FTO solar cell. Our findings reveal impressive values: a maximum open-circuit voltage (Voc) of 1.21 V, a short-circuit current (Jsc) of 32.47 mA/cm2, a fill factor of 87.7 %, and an efficiency (η) of 22.31 %. These findings exceed the previously reported values for halide perovskite based solar cells, underscoring the promise of this research in shaping the future of cutting-edge perovskite-based solar cells.

As the world accelerates its shift toward cleaner, renewable energy, the pursuit of cost-effective, eco-friendly, and highly efficient thin film photovoltaics (TFPV) has become more urgent than ever. In this race, copper antimony sulfide (CuSbS2) stands out with its high absorption coefficient, abundant availability, and low-cost making it a suitable candidate for use as a thin-film absorber layer. However, CuSbS2 solar cells currently achieve only around 3% efficiency, which is far from sufficient. The challenges lie in improper band offsets, high defect densities in the absorber layer, and suboptimal back metal contacts, all of which hinder the efficiency of CuSbS2 (CAS) solar cells. In this work, the structural, electronic and optical properties of the CuSbS2 absorbing layer were thoroughly examined through formation energy, band structure, density of states calculations and absorption coefficient. These analyses reveal that CuSbS2 is a highly promising photovoltaic material, thanks to its optimal direct electronic band gap. The initial simulations closely matched experimental results, providing a solid foundation for further analysis. Optimizing conduction and valence band offsets, along with the thickness and carrier density in the buffer and hole transport layers, led to an impressive efficiency jump from 3.22% to 9.56%. This study delved into how the thickness, carrier density, and defect concentration in the bulk absorber affect photovoltaic performance, uncovering vital correlations that boost efficiency. Finally, fine-tuning the series and shunt resistance and optimizing the back contact work function resulted in a dramatic improvement, achieving an impressive overall efficiency of 19.23%.

Halide perovskites have emerged as leading contenders for next-generation photovoltaic (PV) technology, offering exceptional optical properties, high efficiency, lightweight design, and cost-effectiveness. This study unveils a cutting-edge numerical approach to enhance efficiency in a novel dual-absorber perovskite solar cell (PSC), harnessing eco-friendly inorganic perovskite materials and precise parameter optimization. Initially, we performed comprehensive first-principles calculations of KSnI3 and CsSnI3, revealing their unique direct band gap characteristics of 1.82 eV and 1.26 eV, respectively. Both materials exhibit exceptional absorption coefficients exceeding 105 cm-1 beyond their band gaps, alongside minimal lattice mismatch, making them prime candidates for next-generation high-performance dual-absorber solar cells. In our proposed PSC architecture, KSnI3 acts as the upper absorber layer, while CsSnI3 serves as the lower absorber, complemented by ZnMgO as the electron transport layer (ETL) and NiOx as the hole transport layer (HTL). By utilizing double-graded KSnI3/CsSnI3 materials, our study achieves an impressive efficiency of 30.01%, with an open circuit voltage of 1.11 V, fill factor of 78.1%, and short circuit current of 37.76 mA/cm2. The simulation comprehensively examines the influence of absorber and transport layer thickness, as well as bulk and interface defect densities, on the device’s performance parameters. Additionally, it evaluates the effects of series and shunt resistances and investigates temperature variations to assess performance stability. These insights pave the way for the design and development of next-generation, high-efficiency dual-absorber solar cells.

This study investigates pure and Ni-doped Bi2O3 thin film nanorods (5 % and 10 % Ni@Bi2O3) synthesized via a simple wet chemical method at ambient temperature. Powder X-ray diffraction (PXRD) analysis confirmed the formation of monoclinic crystal structures for all samples, with crystallite size decreasing from 44.22 nm (pure Bi2O3) to 37.34 nm (10 % Ni@Bi2O3), calculated using Scherrer's equation. Tauc's relation revealed a significant reduction in direct bandgap energy from 2.79 eV (pure Bi2O3) to 2.63 eV (10 % Ni@Bi2O3). Photoluminescence (PL) spectra demonstrated enhanced charge carrier dynamics and reduced recombination rates with Ni doping. HR-SEM and HR-TEM analyses confirmed uniform nanorod morphologies. BET surface area analysis indicated a substantial increase from 25.309 m2/g (pure Bi2O3) to 98.010 m2/g (10 % Ni@Bi2O3), facilitating improved dye adsorption and efficient charge transport. Micro-Raman spectroscopy revealed notable changes in vibrational modes due to increased Ni doping concentration, while XPS results confirmed successful incorporation of Ni3+ ions without secondary phase formation. AFM analysis highlighted increased surface roughness, enhancing optical absorption. Electrochemical impedance spectroscopy (EIS) showed reduced charge-transfer resistance, indicating efficient electron-hole separation. Dye-sensitized solar cells (DSSCs) fabricated using 10 % Ni@Bi2O3 exhibited a notable improvement in power conversion efficiency (PCE), increasing from 0.14 % (pure Bi2O3) to 0.40 %. This enhancement is attributed to increased surface area, conductivity, and improved charge transport properties. Additionally, nonlinear optical (NLO) properties were evaluated using the Z-scan technique with a continuous-wave Nd:YAG laser (532 nm wavelength). Results indicated that Ni incorporation significantly enhances both the nonlinear absorption coefficient and refractive index, making Ni@Bi2O3 nanorods promising candidates for nonlinear optical device applications.

This study highlights K2Tl(As/Sb)I6 as a thermodynamically stable, lead-free double perovskite with exceptional bifunctional photovoltaic and thermoelectric performance, making it a promising candidate for next-generation clean energy applications. We have explored the structural, optoelectronic and thermoelectric properties by using DFT while their photovoltaic properties have been explored with the help of SCAPS-1D simulations. The predicted negative formation energy and the lower fluctuation in RMSD obtained through DFT calculations, indicates that K2Tl(As/Sb)I6 is thermodynamically stable. Furthermore, electronic property analysis using the TB-mBJ method reveals that both K2TlAsI6 and K2TlSbI6 possess a desirable direct band gap of 1.16 eV and 1.04 eV, respectively—ideal for optoelectronic applications. The optical analyses unveil remarkable absorption coefficients, soaring to the impressive magnitude of 10⁵ cm⁻¹, beyond the threshold energy of 1.18 eV for K2TlAsI6 and 1.05 eV for K2TlSbI6. These compounds exhibit notable electrical conductivity and minimal reflectivity, attributed to their well-dispersed band structures and optimally aligned band gap values. The thermoelectric evaluation highlights exceptional ZT values of 0.79 and 0.74 at 510 K for K2TlSbI6 and K2TlAsI6, respectively, owing to their ultra-low thermal conductivity (κₑ/τ ~ 1014 W m−1−1 s−1) and remarkably high electrical conductivity (σ/τ ~ 1019 Ω m−1 s−1) over a wide temperature range of 200–650 K. Furthermore, SCAPS-1D simulations unveil outstanding photovoltaic performance, showcasing peak power conversion efficiencies of 30.01% (31.77%) for Ag/Cu2O/K2TlAsI6/TiO2/FTO (Ag/Cu2O/K2TlSbI6/TiO2/FTO), with corresponding JSC values of 40.69 mA/cm2 (45.07 mA/cm2), VOC of 0.93 V (0.81 V), and fill factors of 84.07% (82.21%). These remarkable figures surpass those of recently reported lead-free halide double perovskite solar cells, driven by the excellent electronic and optical characteristics of K2Tl(As/Sb)I6. This study provides a promising pathway toward the realization of next-generation high-efficiency solar cells and thermoelectric devices based on eco-friendly materials.

In this study, three perovskite halide solar cell device models are proposed and simulated using SCAPS-1D software to explore their performance and potential for practical application. Device 1 features a double-absorber-layer hetero-junction structure combining CsGeI3 and CsGeI2Br, while Devices 2 and 3 utilize single absorber layers of CsGeI2Br and CsGeI3, respectively. Spiro-OMeTAD and ZnO were employed as the hole and electron transport layer, respectively, in all three structures. Density functional theory (DFT) was used to study the suitability of CsGeI2Br and CsGeI3 as absorber layers in the proposed device models. Then comprehensive optimization of critical device parameters including absorber layer thickness, defect density, interface defect density and operating temperature were performed to enhance device performance. After optimization, Device 1 demonstrated a significant power conversion efficiency of 21.51%, outperforming Devices 2 and 3 which achieved efficiencies of 16.66% and 15.95% respectively. The superior performance of Device 1 highlights the potential advantages of a double-absorber-layer configuration in improving light absorption and charge carrier dynamics. These results provide a solid foundation for further experimental investigations and feasibility of CsGeI3 and CsGeI2Br-based perovskite structures in the development of high-efficiency solar cells.

Perovskite solar cells (PSCs) are improving in efficiency, but their stability remains a challenge compared to other solar technologies due to the use of hybrid organic–inorganic materials. To overcome this, researchers have shifted focus from methylammonium-based PSCs to more stable cesium (Cs)-based PSCs. By optimizing multi-layer structures to enhance solar spectrum absorption, substantial performance improvements are possible. In this study, we explored single (CsPbIBr2), dual (CsPbIBr2/KSnI3), and triple (CsPbIBr2/KSnI3/MASnBr3) absorber layer designs. The optimization of bilayer and triple-layer PSCs takes into account various factors, such as absorber layer thickness, defect density, and interface defect density for each PSC type. Finally, using the optimal triple-absorber layer combination, we optimized the electron transport layer, hole transport layer, series resistance, and shunt resistance. In this research, we attained impressive efficiencies of 34.22% for the triple-layer solar cell, 20.41% for the bilayer solar cell, and 7.32% for the single-junction PSC. This design approach led to an optimal configuration that showed substantial improvements over the experimental benchmark, including a 7.08% increase in open circuit voltage, a 256.9% increase in short circuit current, a 22.32% increase in fill factor, and a 367.5% increase in efficiency. By meticulously aligning multiple absorber layers in perovskite solar cells, we can unlock new pathways to developing highly efficient solar cells for the future.

Ion migration in mixed halide perovskite (MHP) absorber layers limits the long-term stability of wide-band gap (WBG) solar cells, posing a challenge to commercialization. We address this challenge with an “ionic lockdown” strategy using a vinyl imidazolium-iodine couple, [VIm][I], at the device interface. The iodine counterion effectively occupies surface iodide vacancies, suppressing ion migration. This treatment neutralizes native defects and locks volatile iodide and organic cations, as evidenced by an increase in defect formation energies by ∼0.8 eV and activation energy for ion migration by ∼0.59 eV. We demonstrate this with MAPb(I0.5Br0.5)3, a highly unstable MHP composition. In situ GIWAXS under AM1.5G at 85 °C shows no peak splitting, confirming the photostability. Devices treated with [VIm][I] retain 90% power conversion efficiency (PCE) under continuous illumination and recover 99% PCE in the dark. These results highlight the potential of [VIm][I] for enhancing the stability of WBG cells across different compositions, paving the way for more durable perovskite-based photovoltaic technologies.

Lead-free double perovskite halides are attracting considerable interest in the optoelectronics sector due to their remarkable electronic, optical, and transport properties. These materials are not only stable and easy to synthesize but also present a wide range of potential applications. This study investigates the fascinating characteristics of Rb₂LiGa(Br/I)₆, focusing on its structural, electronic, optical, transport, and photovoltaic attributes. Our findings indicate that Rb₂LiGaBr₆ and Rb₂LiGaI₆ have band gaps of 1.19 eV and 1.13 eV, respectively, highlighting their versatility for various applications. Both compounds exhibit exceptional optical properties, featuring high absorption coefficients and optical conductivity, along with low reflectivity throughout the UV-visible spectrum, positioning them as excellent candidates for solar cell technologies. Moreover, Rb₂LiGa(Br/I)₆ demonstrates impressive thermoelectric performance, with high figure-of-merit (ZT) values between 200 K and 800 K, indicating their potential as effective thermoelectric materials. Consequently, this study offers valuable insights for the development of efficient double perovskite-based solar cells. Encouraged by the outstanding absorption and optical conductivity of Rb₂LiGa(Br/I)₆, we simulated an Au/Cu₂O/Rb₂LiGa(Br/I)₆/TiO₂/FTO solar cell. Our results reveal that the modeled solar cell, Au/Cu₂O/Rb₂LiGaI₆/TiO₂/FTO, achieves an efficiency of 26.48%, surpassing previous reports. This research sets a new benchmark for high-performance double perovskite-based solar cells and lays the foundation for future advancements in this exciting area.

In this article, we have performed first-principles studies on structural stability, magnetic, electronic, and thermoelectric properties of (K/Rb)2MnF6. The structural optimization shows the ferromagnetic ground state with high Curie temperature (TC) of 609K and 596K for K2MnF6 and Rb2MF6 respectively. Also, the estimated tolerance and octahedral factor demonstrated the cubic phase stability of (K/Rb)2MnF6. In addition, the spin-polarized electronic studies revealed the half-metallic nature of these systems. Further, the spin-based thermoelectric prediction showed the higher figure of merit (ZT) of the down channel originated from the higher Seebeck coefficient with low thermal conductivity of both compounds. Altogether,(K/Rb)2MnF6 are potential candidates for spintronic and spin-based thermoelectric applications.

In this article, we have systematically investigated the structural, electronic, magnetic, and spin-based thermoelectric properties of K2W(Cl/Br)6 by first-principles calculation. The obtained negative formation energy confirmed the thermodynamic stability of K2W(Cl/Br)6, while the tolerance factor calculation showed their cubic phase stability. In addition, we have estimated the elastic constants which confirmed the mechanical stability of K2W(Cl/Br)6. Further, the spin-polarized band structure and density of states calculations revealed the half-metallic nature with high Curie temperature (Tc) values of 613 K and 597 K for K2WCl6 and K2WBr6, respectively. Moreover, we have studied the temperature variation of thermoelectric properties such as kl, σ, ke, S, PF, and ZT. Such results showed that higher ZT values for spin-down channels are obtained from ultra-low ke, and high PF. Therefore, K2W(Cl/Br)6 are viable thermoelectric and spintronic materials.

Charge-carrier recombination within the photoactive and charge extraction layers is one of the major obstacles to achieve high performance perovskite solar cells. Here, we demonstrate an ultrathin layer of ZnOS in between SnO2 and halide perovskite film that can effectively passivate the defects, suppressing the nonradiative recombination loss. It also helps to moderate the perovskite layer with increasing surface potential, which facilitates transferring the carriers from the perovskite to the hole transport layer, consequently providing an understanding of the bottom-up interfacial passivation of perovskite films. An enhancement of VOC ~ 100 mV mainly causes the efficiency improvement from 17.22 to 19.4% in the combined SnO2-ZnOS based solar cell. In addition, we have performed a device modeling and theoretical analysis of these perovskite solar cells with and without the passivation layer. Theoretical results for the electronic band structure indicate that ZnOS contains an intermediate band structure between SnO2 and perovskite resulting in a much better band bending for the SnO2-ZnOS based solar cells. It is observed that the numerical results are in good agreement with the experimental outcomes. The combined electron transport layer strategy provides a way for defect passivation for further efficiency enhancement of the perovskite solar cells through interface engineering.

In recent years, the metal halide perovskites (MHPs) have gained substantial interest due to their versatile applications in the field of the solar cell, Field-Effect Transistor (FET), and Light-Emitting Diode (LED), sensor, photocatalyst, etc. However, instability and toxicity are two major issues hindering their large-scale commercialization. In this regard, the growth of lead-free halide double perovskites is crucial to solving the above issues. The lead-free halide double perovskites have versatile applications as photovoltaic, thermoelectric, spintronic, LED, and photocatalytic materials. This article discussed both theoretical and experimental assessments of the optical, electronic, magnetic, and thermoelectric properties of lead-free halide double perovskites. In addition, we have discussed their structural, mechanical, and thermal stabilities of lead-free halide double perovskites with the help of experimental and theoretical data. Furthermore, we have highlighted the up-to-date progress of lead-free halide double perovskites for applications in the field of photovoltaic, field-effect transistor (FET), and light-emitting diode (LED), photocatalyst, thermoelectric, spintronic, and memristors. Finally, challenges and future outlooks for using these materials for said applications are discussed.

Rb2Tl(As/Bi)I6 are predicted to be good photovoltaic and thermoelectric materials. In this article, we have carried out firs-principles investigation on structural, electronic, optical and thermoelectric properties of Rb2Tl(As/Bi)I6. The obtained negative formation energy along with absence of imaginary frequency in phonon dispersion curve demonstrated the thermodynamic stability of Rb2Tl(As/Bi)I6. Also, the obtained electronic band structure with new mBJ functional showed the band gap values of 1.05 eV and 1.63 eV for Rb2TlAsI6 and Rb2TlBiI6, respectively. In addition, the out shining optical properties such as higher order (105 cm−1) of absorption coefficient, appreciable optical conductivity and low reflectivity of Rb2Tl(As/Bi)I6 are resulted from the dispersed direct band gap with suitable values of Rb2Tl(As/Bi)I6. Furthermore, ultra-low thermal conductivity and high electrical conductivity leads to higher ZT values of titled systems. Thus, Rb2Tl(As/Bi)I6 are emerging photovoltaic and thermoelectric materials.

In this article, we have systematically investigated the structural, electronic, optical, and thermoelectric properties of Cs2Tl(As/Sb)I6. The obtained negative formation energy along without the presence of imaginary phonon frequency confirmed the thermodynamic stability of Cs2Tl(As/Sb)I6. In addition, the new mBJ approach showed the direct band gap value of 1.10 and 1.33 eV for Cs2TlAsI6 and Cs2TlSbI6, respectively. Furthermore, the dispersed direct band nature of Cs2Tl(As/Sb)I6 leads to their outshining optical properties such as higher-order (105 cm−1) absorption coefficient, appreciable optical conductivity, and low reflectivity. Moreover, the higher figure of merit values of Cs2Tl(As/Sb)I6 are resulted from their ultra-low thermal conductivity and high electrical conductivity. Thus, Cs2Tl(As/Sb)I6 are predicted to be potential photovoltaic and thermoelectric materials.

In this article, we have systematically investigated the structural, electronic, optical and thermoelectric properties of Rb2Ag(Ga/In)Br6. The resulting negative formation energy along with the absence of imaginary phonon modes confirm the thermodynamic stability of Rb2Ag(Ga/In)Br6. In addition, the derived electronic properties by using GGA-PBE + mBJ + SOC functional show that the direct band gap values are 1.21 eV and 1.42 eV for Rb2AgGaBr6 and Rb2AgInBr6, respectively. Furthermore, the dispersed direct band nature of Rb2Ag(Ga/In)Br6 leads to their outshining optical properties such as higher order (105 cm−1) absorption coefficient, appreciable optical conductivity, and low reflectivity. Moreover, the higher figure of merit values of Rb2Ag(Ga/In)Br6 are resulted from their ultra-low thermal conductivity and high electrical conductivity. Thus, Rb2Ag(Ga/In)Br6 are predicted to be potential photovoltaic and thermoelectric materials.

Cs2GeSnCl6 is predicted to be an emerging material for the construction of high-efficiency solar cells. In this article, we have explored the structural, optoelectronic and photovoltaic properties of Cs2GeSnCl6 by using first-principles and SCAPS-1D simulations. The formation energy and phonon band structure calculations confirmed the thermodynamic stability of Cs2GeSnCl6. The electronic property of Cs2GeSnCl6 revealed a direct band gap of 0.91 eV (with SOC) by using the mBJ exchange-correlation functional. The optical calculations ensured a high absorption coefficient and low reflectance. Furthermore, the simulated photovoltaic performance of Cs2GeSnCl6-based heterojunction solar cell i.e. ITO/SnO2/ Cs2GeSnCl6/Au shows the optimum PCE (%) of 16.35 %, which is higher than the recently predicted PEC (%) value from Cs2AgBiBr6 based solar cell.

Reduction in band gap of zinc oxide is the key requirement to enhance the photo conductivity of the material under visible light irradiation, which will helpful to fabricate high efficiency energy harvesting solar cell. Herein, 3d transition metal doped 2 × 2 × 2 supercell of wurtzite ZnO has been studied using full potential linearized augmented plane-wave (FP-LAPW) method within the DFT implemented in WIEN2k code. As a result of doping, many impurity levels have been observed in the band gap region of the pure ZnO, which are effectively reduce the band gap of the material. Total density of states (TDOS) plots reveal that the Fe, Ni, Co-doped ZnO show both p-type and n-type conductivity of the samples, whereas Cu-doped ZnO shows only p-type conductivity as all the impurity levels lie below the Fermi level when Cu dopant is used. Hence the present study is not only important for the basic understanding of the 3d transition metal doping effect ZnO but also has a tremendous application in designing high efficiency energy harvesting solar cell.

Large area surface micro-structuring is most commonly used to reduce the reflection loss and improve the light absorption in solar cells, photo-detectors and image sensors. Herein, chemically prepared textured GaAs with improved absorption in the entire range of the solar spectrum is investigated using UV–Vis–NIR spectrometer, showing that an average specular reflectance can be reduced to ~ 0.2% in the wavelength range of 3000–300 nm. The sputtered MoO 3 thin film (10 nm) on textured GaAs further reduces the reflection loss down to ~ 0.1% (average value) in same wavelength range, i.e., 300–3000 nm. The phase, morphology, composition, and transport properties of the thin films were investigated using XRD, SEM, AFM, XPS, and Keithley source meter, respectively. SEM and AFM scanning show highly ordered elongated microstructure has been induced on pristine GaAs substrate after wet chemical etching. XRD analysis shows amorphous nature of the MoO 3 thin film. In addition, XPS studies confirm that MoO 3 thin film present on the surface of textured GaAs. Moreover, hole-blocking property of the MoO 3 thin film has been studied with the help of Anderson model. Further, current–voltage characteristics (under dark condition) show rectifying behavior of the heterojunction (Ag/MoO 3 /GaAs/Ag). Hence, the present study is not only important for the basic understanding of charge transports across the heterojunction, but also to also to design hole-blocking-based solar cell.