Abstract On account of their environmentally-benign composition and structural stability, lead-free halide double perovskites have drawn increasing attention. Even though the charge-transport behavior of Cs₂NaInCl₆, one of these perovskites, remains poorly understood under illumination, it shows strong self-trapped exciton (STE) emission. Through a combined optical and electrical approach, this work investigates the interplay between electrical transport and exciton dynamics. With a wide bandgap and intrinsic STE-mediated blue emission, a highly crystalline cubic phase is confirmed by the optical and structural analyses. Multi-timescale photoinduced relaxation dynamics associated with recombination processes, lattice relaxation and exciton localization are inferred primarily from TRPL measurements and qualitatively supported by complementary transient absorption observations. Current–voltage measurements, dielectric analysis and complementary impedance spectroscopy evidence that illumination significantly reduces bulk resistance, enhances dielectric polarization and induces persistent photoconductivity. While the optical response is governed by STEs, the results indicate that photo-generated carriers dominate charge transport with an indirect influence of exciton dynamics through trap-state modulation. New insight into the optoelectronic functionality of lead-free double perovskites is provided through a physically-consistent framework proposed to correlate macroscopic transport properties with microscopic excitonic behavior.

On account of their environmentally-benign composition and structural stability, lead-free halide double perovskites are known for being good substitutes for Pb-based materials. This paper includes a detailed examination of the electrical, optical and structural properties of Cs₂NaInCl₆. It also shows unified photo-physical properties and a charge-transport mechanism controlled by innate self-trapped excitons (STEs). An excellent thermal stability reaching 620°C is confirmed through thermogravimetric analysis while a highly crystalline cubic \(Fm\stackrel{-}{3}m\) phase is demonstrated by X-ray diffraction. Optical absorption, however, provides not only a low Urbach energy (0.31 eV) which confirms minimal disorder but also a wide direct bandgap (4.81 eV). A broad intrinsic blue emission which originates from STEs and a reduced electron–phonon coupling at low temperatures are revealed through temperature-dependent and steady-state photoluminescence measurements. A multi-step relaxation pathway that includes the formation of long-lived localized states, lattice relaxation and ultrafast exciton self-trapping is demonstrated using transient absorption spectroscopy and time-resolved PL. It is proven that Illumination activates persistent photocarriers, improves polarization and reduces the bulk resistance considerably by means of dielectric analysis, electric-modulus modeling and impedance spectroscopy. A strong voltage-independent photoconductive gain reaching three orders of magnitude is further proven by I–V measurements without altering the underlying ohmic transport regime. These results collectively set up a coherent microscopic picture where carrier stabilization, trap filling and STE formation together influence not only the AC/DC transport properties but also the optical emission. Hence, as a lead-free perovskite having strong potential for radiation-detection, dielectric and UV-emitting applications, Cs₂NaInCl₆ seems highly stable, robust and intrinsically-excitonic.

This work represents the first use of a phosphonium salt-functionalized β-Cyclodextrin polymer (β-CDP) as a highly selective sensing membrane for monitoring the safety of drinking water against perchlorate ions (ClO4−) using electrochemical impedance spectroscopy (EIS). Structural confirmation via 1H NMR, 13C NMR, 31P NMR, and FT-IR spectroscopies combined with AFM and contact angle measurements demonstrate how the enhanced solubility of modified cyclodextrin improves thin film quality. The innovation lies in the synergistic combination of two detection mechanisms: the “Host-Guest” inclusion in the cyclodextrin cavity and anionic exchange between the bromide ions of the phosphonium groups and perchlorate anions. Under optimized functionalization conditions, EIS reveals high sensitivity and selectivity, achieving a record-low detection limit (LOD) of ~10−12 M and a wide linear range of detection (10−11 M–10−4 M). Sensing mechanisms at the functionalized transducer interfaces are examined through numerical fitting of Cole-Cole impedance spectra via a single relaxation equivalent circuit. Real water sample analysis confirms the sensor’s practical applicability, with recoveries between 96.9% and 109.8% and RSDs of 2.4–4.8%. Finally, a comparative study with reported membrane sensors shows that β-CDP offers superior performance, wider range, higher sensitivity, lower LOD, and simpler synthesis.

ABSTRACTLead‐free double perovskites, such as Cs2AgInCl6, represent a promising class of materials for optoelectronic applications due to their favorable properties and environmental sustainability. This work focuses on the synthesis and comprehensive characterization of Cs2AgInCl6, employing a range of techniques including X‐ray diffraction (XRD) for structural verification, thermogravimetric analysis (TGA) to assess thermal stability, and UV–visible absorption measurements to determine the optical bandgap energy of 3.32 eV. Additionally, we explore photoluminescence (PL) and decay measurements to elucidate the luminescent properties of the compound. Complex impedance measurements are performed under both blue and red light to investigate the electrical behavior, revealing two distinct conduction mechanisms: the overlapping large–polaron tunneling (OLPT) and nonoverlapping small–polaron tunneling (NSPT). We analyze the implications of our findings on the current–voltage (I–V) behavior and trap density, further supported by Raman spectroscopy under both illumination conditions. The combined insights from optical and electrical characterizations highlight the potential of Cs2AgInCl6 in optical applications, paving the way for its use in advanced optoelectronic devices.

Lead-free tin halide perovskites, particularly Cs2SnBr6, are gaining significant attention for their potential in optoelectronic applications. In this study, we investigate the material's electrical and vibrational properties under varying illumination conditions, providing novel insights into the impact of light on its conduction mechanisms. Cs2SnBr6 was synthesized via liquid-phase and solid-state reactions, and we report comprehensive analyses of its impedance, AC conductivity, and dielectric properties over a wide frequency range. Notably, our results reveal that light-induced photogenerated charge carriers enhance conductivity, which is well explained by the overlapping large-polaron tunneling (OLPT) model, while in darkness, the material follows the correlated barrier hopping (CBH) model. Moreover, Raman spectroscopy highlights structural changes, including a slight shortening of Sn-Br bond distances under illumination, which influences the vibrational frequencies and intensities. These findings emphasize the crucial role of illumination in tuning the electrical and dielectric responses of Cs2SnBr6, thus demonstrating its considerable promise for future optoelectronic applications, such as solar cells and photodetectors.

Lead halide perovskites (LHPs) have attracted considerable attention due to their exceptional photophysical properties, positioning them as promising candidates for advanced optoelectronic applications. However, their broad commercialization, particularly in photovoltaics, is limited by the inherent toxicity of lead. To address this issue, research efforts have progressively shifted towards the development of environmentally benign, lead-free perovskite alternatives. In the present study, the structural, optical, and electronic properties of A2AgBiBr6 (M = CH3NH3, K) double perovskites were comprehensively analyzed to assess their viability as non-toxic substitutes. Through powder X-ray diffraction, scanning transmission electron microscopy, and thermogravimetric analysis, the structural integrity and thermal resilience of the materials were elucidated. Optical characterizations revealed a direct bandgap of 3.07 eV for K2AgBiBr6 and an indirect bandgap of 1.79 eV for (CH3NH3)2AgBiBr6, demonstrating their complementary suitability for various optoelectronic applications. Additionally, carrier dynamics, investigated through time-resolved photoluminescence and transient absorption spectroscopy, revealed superior structural order and efficient charge transport in K2AgBiBr6. These results underscore the critical influence of A-site cation engineering on the modulation of photophysical properties, providing valuable insights for the design of sustainable, high-performance lead-free perovskite materials for next-generation optoelectronic technologies.

The exploration of lead-free halide double perovskites has emerged as a strategic route toward sustainable optoelectronic technologies. In this work, we present a comprehensive study of Cs2NaEuCl6, a lanthanide-based double perovskite, synthesized via a modified evaporation method. The compound crystallizes in a cubic phase and exhibits efficient Eu3+ 4f-4f emission with a direct band gap of similar to 3.37 eV. Photoluminescence analysis reveals intense red emission and a long excited-state lifetime of similar to 3.17 ms, surpassing values reported for similar systems and confirming a low non-radiative defect density. Under AM1.5G illumination, Cs2NaEuCl6 demonstrates persistent positive photoconductivity with a recovery time of similar to 180 min and a marked reduction of charge transfer resistance from similar to 11 k Omega to similar to 3.5 k Omega, evidencing stable light-induced conductivity. Ultrafast transient absorption uncovers sub-picosecond carrier thermalization and few-picosecond recombination dynamics, while Raman spectroscopy verifies structural integrity under prolonged illumination. These findings demonstrate, for the first time, the coexistence of long-lived radiative recombination and stable photoconductivity in Cs2NaEuCl6, establishing it as a robust dual photonic-electronic platform for next-generation optoelectronic applications, including photonic sensors, UV photodetectors, and light-emitting devices.

Cs2AgBiBr6 double perovskites have attracted considerable interest for optoelectronic applications owing to their favorable structural stability and nontoxic composition. In this study, we systematically investigate the influence of two crystal growth methods-Single Crystal Growth (SCG) and Seed-Assisted Growth (SAG)-on the morphology, crystallinity, defect landscape, and optoelectronic properties of Cs2AgBiBr6 single crystals. Comprehensive characterization using scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), time-resolved photoluminescence (TRPL), impedance spectroscopy, and current-voltage (I-V) measurements reveals that the SAG method yields significantly larger and more uniform grains, improved structural coherence, and reduced defect densities compared to the SCG route. The narrower XRD peaks and reduced lattice strain in SAG-grown crystals confirm their higher crystallinity, while TRPL analysis shows extended carrier lifetimes, indicating suppressed nonradiative recombination due to fewer trap states. These structural and optical improvements directly enhance device performance, as SAG-grown crystals exhibit a 2.5-fold increase in photocurrent and a markedly lower dark current in photodetector configurations. Our findings establish the SAG technique as a superior and scalable approach for producing high-quality Cs2AgBiBr6 crystals, positioning them as promising candidates for next-generation optoelectronic devices, including photodetectors and light-emitting components.

The structural and electronic properties of fullerenes, particularly C60, have garnered significant interest due to their unique characteristics, making them promising candidates for advanced applications in photodetectors, diodes, and solar cells. Fullerenes, a class of zero-dimensional nanomaterials, exhibit exceptional thermal and electrical conductivity, as well as high tensile strength. Their ability to readily accept and donate electrons positions them as key components in optoelectronic devices. This review explores the functionalization, atomic structure, and morphology of fullerenes, emphasizing their roles in improving charge transfer efficiency and electron mobility in photodetectors, organic photovoltaic cells, and diodes. Recent advancements, such as functionalized fullerene derivatives, have demonstrated substantial improvements in device performance, including enhanced broadband detectivity and near-infrared (NIR) photodetection. Furthermore, developments in hybrid nanomaterials combining fullerenes with other semiconductors, such as PbS nanocrystals, have enabled remarkable gains in responsivity and efficiency. These findings highlight the potential of fullerenes as cost-effective and high-performance alternatives for next-generation optoelectronic applications.

As a typical normal spinel, LiCo2O4 is suitable for use in either optoelectrical materials or storage vehicle generations as Li-ion secondary batteries. Herein, we report on the fabrication of microporous particles. LiCo2O4 spinel microstructure was created directly through the solid-state method of synthesis. The structure and particle size of our spinel were checked by X-ray diffraction (XRD) and scanning electron microscopy (SEM), whereas the optical studies were carried out using the experimental Ultraviolet-visible (UV-visible). The energy gap was established to be 2.33 eV and shows the potential of this compound in the optoelectronic domain. The corresponding electrical properties are studied as the Nyquist diagrams, the modulus contributions, and the ac-conductivity. This study proves the good electrical performances, which showed an ac-conductivity value in the order of 10-4 Omega-1cm-1. However, this investigation presents an effect due to the adsorbing H2O at a temperature range between 353 and 393 K. The exponent (s) shows that the nonoverlapping small polar on tunneling (NSPT) conduction model describes the phases before the adsorbed H2O molecules of this material and the overlap tunnel of large polaron tunneling (OLPT) is the appropriate model at high temperatures.

Cs₂AgBiBr₆ double perovskites have emerged as promising materials for optoelectronic applications due to their unique structural and electronic properties. This study systematically compares two crystal growth techniques-Single Crystal Growth (SCG) and Seed-assisted Growth (SAG) to evaluate their impact on crystal quality, defect density, and optoelectronic performance. While both methods yield similarly sized crystals, the SAG method produces superior-quality crystals with reduced defects, improved crystallinity, and enhanced structural coherence. Comprehensive characterization using X-ray diffraction (XRD), photoluminescence (PL), time-resolved photoluminescence (TRPL), impedance spectroscopy, and current-voltage (I-V) measurements reveals that SAG-grown crystals exhibit lower lattice strain, fewer trap states, and higher charge carrier mobility. These improvements translate into a 2.5-fold increase in photocurrent response and a significantly lower dark current in photodetectors based on SAG-grown crystals. The results highlight the SAG method as a more effective and reproducible approach for fabricating high-quality Cs2AgBiBr6 single crystals, making them ideal for advanced optoelectronic devices such as photodetectors and light-emitting components.

Lead-free halide double perovskites are gaining attention as sustainable and stable alternatives to lead-based counterparts. Here, we report a detailed investigation of the vacancy-ordered double perovskite Cs2SnCl6, synthesized via a simple chemical precipitation method. X-ray diffraction confirmed its cubic Fm3m symmetry, with a refined lattice parameter of a = 10.3847(4) Å. Thermogravimetric analysis demonstrated outstanding thermal stability up to 614.4°C, highlighting its robustness for high-temperature processing. Optical measurements revealed a wide direct bandgap of 3.60 eV and an Urbach energy of 0.425 eV, indicating low structural disorder and strong intrinsic excitonic effects. Photoluminescence analysis showed a broad emission centered at 433.88 nm with bi-exponential decay lifetimes of τ1 ≈ 7.85 ns and τ2 ≈ 281.3 ns, confirming the role of self-trapped excitons. Impedance spectroscopy between 303 K and 403 K identified thermally activated ionic transport with two distinct activation energies (0.32 eV and 0.10 eV), corresponding to a transition from trap-limited to bulk-dominated conduction around 350 K. Complementary dielectric and modulus analyses further evidenced non-Debye relaxation governed by hopping conduction and Maxwell–Wagner–Sillars polarization. These findings establish Cs2SnCl6 as a thermally robust and multifunctional material with promising potential in UV photodetectors, ion-conducting devices, and scintillation technologies.

Plants offer a bountiful source of natural pest control solutions through their essential oils. This research introduces and analyzes an eco-friendly natural essential oil for red flour beetle control. Therefore, the current study was included to show the chemical profile and the insecticidal efficacy of resin essential oil (REO) and its fractions (F1–3), resulting from chromatographic separation, from the plant Schinus molle against Tribolium castaneum adults. The trunk bark resin essential oil and its fractions’ composition were analyzed by GC-MS. Overall, 33 constituents with 98.3% of the total EO composition were identified. REO and F1–3 displayed impressive repellent properties at a concentration of 0.12 µL/cm2. After 120 min of exposure, repellency ranged from 73.3% to a remarkable 96.7%. They also exhibited noteworthy fumigant properties, with median lethal doses of LD50 = 120.6–160.8 μL/L. The fractions F1 and F3 showed the most notable topical toxicity at a concentration of 10%, with LD50 values of 8.6% and 5.6%, respectively. Fractions F3 and F2 demonstrated the most effective inhibition of acetylcholinesterase (AChE) activity, providing insight into their insecticidal mechanisms. The in silico molecular docking and DFT studies corroborate the results of in vitro tests performed to identify new insecticide products derived from natural sources.

In this study, we present the synthesis of a novel host-guest polyrotaxane (PR1) using a microwave-assisted threading approach. The polyrotaxane structure involves the encapsulation of an anthracene-based conjugated polymer (P1) within β-cyclodextrin (β-CD) cavities. The successful formation of PR1 and P1 was confirmed using various spectroscopic and thermal techniques. Optimized geometry and vibrational frequencies of the polymer P1 conducted using DFT calculations at the DFT/B3LYP/6-311+G(d) level of theory showed good agreement with experimental results. Physicochemical and electrical properties of PR1 and the free polymer P1 revealed significant improvements resulting from the encapsulation process. Particularly, enhanced solubility in DMF and DMSO and processability, improved thermal stability, surface homogeneity, and smoothness in PR1 compared to the free polymer. Additionally, the encapsulation process led to an enhanced redox potential of PR1 in comparison to the free polymer. Interestingly, the photoluminescence of thin films of P1 was found to be quenched due to a phenomenon known as aggregation caused quenching (ACQ). However, the encapsulation of the polymer using β-CD rings reduced the formation of aggregates, effectively suppressing the ACQ process. This resulted in the recovery of photoluminescence. Notably, the charge carrier mobility of the encapsulated polymer was maintained at a similar order of magnitude.

In this work, we describe the design and synthesis of a novel soluble conjugated molecule, CAR-TzDPP, consisting of a central diketopyrrolopyrrole core (DPP) connected to carbazole endcaps through thiazole rings. To evaluate its properties, a triazatruxene-based molecule (TAT-TzDPP) was used as a model for comparison. The electrochemical and the in-solution optical properties are in good agreement with those obtained from DFT calculations. However, the thin-film self-assemblies of CAR-TzDPP exhibited distinct differences, forming a more standard crystalline structure including insulating side-chains layers that disallowed side interactions between aromatic rings. This resulted in a reduced charge transport ability to a two-dimensional (2D) ambipolar charge transport in CAR-TzDPP, compared to the nearly isotropic unipolar charge transport in TAT-TzDPP. Despite this, CAR-TzDPP can be considered a viable alternative for device configurations requiring semiconducting pathways aligned in the substrate plane due to its simplified and high yield synthesis route, ease of processing, and reliable charge mobility in OFETs. This research highlights the significance of molecular units in small semiconducting organic molecules, not only in terms of their individual optoelectronic properties but also in terms of their self-assembly capabilities, which ultimately influence their charge transport properties.

This paper covers the conception of new soluble and filmogene conjugated polymers (PAnSCN and PAnSCN-Tet) for heavy metal sensing application. The prepared materials are based on the highly emissive anthracene chromophore and contain tetrazole and/or cyanide groups in their molecular chain backbones. The effect of the electron withdrawing groups on photophysical properties and the chelating abilities of the elaborated organic materials were investigated. The optical analysis shows that the CN groups reduced slightly the optical band-gap of the polymer, however the steric hindrance of tetrazole units dominates their electronic effects leading to a blue-shift of its absorption spectrum. Also, the electrochemical study reveals a considerable electronic affinity increase by 0.84 eV when passing from PAnSCN into PAnSCN-Tet. DFT calculations has been employed to estimate the optimized macromolecular structure of both polymers and a notable change in geometry in terms of planarity was observed depending on the incorporated withdrawing group. The synthesized polymers were studied as optical sensors. The changes in the photoluminescence intensity were used to evaluate the binding affinity of the two materials to different metal ions. The obtained results showed considerable decrease in photoluminescence (quenching) responses with Mn2+ cations a short time after adding the cations to both polymer solutions with better sensitivity and selectivity in the case of the PAnSCN-Tet.

In this work, we report the benzylation of an anthracene and beta-Cyclodextrin-based rotaxane. Then, a comparative study between the physicochemical and electrical properties of the modified rotaxane (R-Bn) and those of the pristine supramolecule (R) was conducted. We noted an important improvement of the solubility of the rotaxane following the o-benzylation of the beta-Cyclodextrin hydroxyl groups. The analysis of the surface topography of the rotaxane films using atomic force microscopy (AFM) showed a smoother surface morphology for the supra-molecular assembly R-Bn. Also, we have demonstrated that the introduction of benzyl moieties induces a remarkable broadening and a bathochromic shift of the UV-visible absorption and photoluminescence spectra, an improvement in the fluorescence yield as well as a reduction of the optical and electrochemical band gaps. In addition, a white photoluminescence was emitted from R-Bn thin layer while a blue emission was observed in the case of the primitive rotaxane film (R). Regarding the electrical measurements, the benzylation of the rotaxane induced a dramatic decrease of the threshold voltage (from 3.70 V to 1.55 V) and the dynamic resistances (from 113.84 k Omega to 11.51 k Omega), an important increase by one order of magnitude of the charge carrier mobility and a drastic increase of the conductivity by 5 orders of magnitude.

An effective and simple carbazole-based Schiff base (CrbPy2) chemosensor for selective recognition of Cr(III) was designed and synthesized. The molecular structure of CrbPy2 was confirmed by NMR and FT-IR spectroscopies, its crystal structure was investigated by XRD analysis and the results were in good agreement with the DFT calculations. The CrbPy2 probe showed high selectivity toward Cr3+ ions in THF/H2O (95/5%) solution. Adding Cr3+ ions to CrbPy2 dilute solution induced a naked eye color change from colorless to yellow accompanied with a fluorescence turn-on. The proposed sensing mechanism was related to chelation-enhanced fluorescence (CHEF) process. The stoichiometry ratio of CrbPy2-Cr3+ complex is 1:1 with an association constant exceeding 3 x 105 M-1. The study of the sensing properties in different pH showed that CrbPy2 can tolerate the detection of Cr3+ ions in a pH range from 6 to 8. The chelating sites of the chemosensor and the coordination geometry of the complex were determined using 1H NMR titrations and MEP calculations. The detection was completed within 2-3 min and the detection limit reaches 1.08 mu M. The linear recognition range of Cr(III) is from 1.08 mu M to 4 mu M making CrbPy2 a suitable probe for real-time identification of unsafe Cr3+ concentration in drinking water.

Synthesis of beta-iminoamine (beta-IA) heterocyclic ligand and its corresponding tetrachlorocobaltate(II)-based hybrid material [beta-IA](2)[CoCl4] was achieved (beta-IA(+) = 4-(dimethylhenylamino)-2-(dimethylbenzenamine)pente-3-enium). Compounds were fully characterized through H-1 NMR, C-13 NMR, IR, UV-Vis spectroscopies and single crystal X-ray diffraction (SC-XRD) as well as state-of-the-art quantum chemical approaches. It is found that supramolecular solid-state architecture is primarily ensured by classical N-H center dot center dot center dot Cl hydrogen bonding. Hirshfeld surfaces (HS) and non-covalent interaction (NCI) index proved the existence of non-conventional C-H center dot center dot center dot Cl and C-H-center dot center dot center dot pi interactions. Bader's theory of atoms-in-molecules (AIM) conjointly with natural bond orbital (NBO) demonstrated that hydrogen bonds are medium strength and possess a dominant character of the purely noncovalent electrostatic interactions in nature. Moreover, electronic absorption properties were simulated using time-dependent density functional theory (TD-DFT) method and compared with the experimental data. Finally, synthesized compounds were screened for their in vitro antimicrobial activities. (C) 2021 Elsevier B.V. All rights reserved.

In this study, we describe the synthesis of a host-guest supramolecule (TDPAn beta-CD) formed from an anthracene-based conjugated molecule (TDPAn, guest) encapsulated in cyclodextrin (beta-CD, host) under microwave irradiation. The obtaining of the desired rotaxane was confirmed by different spectroscopic and thermal analyzes. A comparative study between the physicochemical and electrical properties of the free molecule (TDPAn) and those of the rotaxane (TDPAn beta-CD) was conducted. Thermal analyzes show an amorphous morphology and good thermal stability for the rotaxane. The surface morphology of the synthesized materials was studied using atomic force microscopy and contact angle measurement. The supramolecular film exhibits a smooth and homogeneous surface with a relatively low surface roughness compared to that of the free model. The absorption and photoluminescence spectra of the rotaxane thin film are blue-shifted in comparison with TDPAn, due to a steric hindrance effect of the beta-CD. Hence, a blue intense photoluminescence was emitted from the rotaxane layer, compared to a violet-red emission in the case of non-encapsulated TDPAn. Higher electron affinity and ionization potential for the host-guest supramolecule were observed by cyclic voltammetry. The static study of ITO/TDPAn/Al and ITO/TDPAn beta-CD/Al schottky single layer diodes showed typical behaviors with relatively low threshold voltages and higher charge carrier mobility was achieved for the rotaxane active layer.