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Transparent conductive oxides such as indium tin oxide (ITO) substrates are commonly employed as prime materials for optoelectronic applications. Enhancement in functions of such devices often compels stable and robust modification of the ITO substrate to improve its interfacial charge transfer characteristics. Thereby, in this work, naphthyl modifier multilayer films are fabricated on LTO substrate using conventional electrochemical reduction of 1-naphthyl diazonium salts (NAPH-D) via altering its concentration ranging from 2 mM to 12 mM with a step size of 2. Surface coverage was significantly tuned by varying NAPH-D concentration, keeping other parameters such as the number of scans and scan rate constant. For lower concentrations (2 mM), the molecular thickness ~6 nm was obtained, whereas higher concentrations (12 mM) produced around 15-18 nm thickness. Atomic force microscopy (AFM), cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) in the presence of a ferrocene redox probe also supports the formation of well packed molecular film grown on the ITO surface. Further, the wettability property of the grafted naphthyl film was investigated at different surface coverages and correlated with charge transfer resistance ([R.sub.Ct]) obtained from EIS studies. Key words: electrochemical grafting, naphthyl diazonium salts, multilayer film, surface coverage, charge transfer resistance. Les oxydes conducteurs transparents tels que les substrats d'oxyde d'indium-etain (aussi appele ITO pour l'anglais indium-tin oxide) sont couramment utilises comme matieres premieres dans les dispositifs optoelectroniques. L'extension des fonctionnalites de ces dispositifs requiert souvent une modification stable et robuste du substrat d'ITO dans le but d'ameliorer ses caracteristiques de transfert de charge interfacial. Ainsi, dans le cadre des presents travaux, nous avons fabrique des films multicouches modifies par des groupes naphtyles sur un substrat d'lTO par reduction electrochimique classique de sels de 1-naphtyldiazonium (NAPH-D), en faisant passer leur concentration de 2 mM a 12 mM par increments de 2 mM. Nous avons regie avec une precision substantielle le recouvrement de la surface en faisant varier la concentration de NAPH-D, tout en maintenant constants d'autres parametres tels que le nombre de balayages et la vitesse de balayage. [Angstrom] la concentration la plus faible (2 mM), nous avons obtenu un film d'epaisseur moleculaire, soit environ 6 nm, tandis qu'a la concentration la plus elevee (12 mM), nous avons obtenu un film d'environ 15 a 18 nm d'epaisseur. La microscopie a force atomique (AFM), la voltamperometrie cyclique et la spectroscopic d'impedance electrochimique (SIE) en presence d'une sonde redox a base de ferrocene appuient egalement la formation bien compacte de films moleculaires et leur croissance a partir de la surface d'lTO. En outre, nous avons etudie la mouillabilite du film de naphtyle greffe a differents degres de recouvrement de la surface et nous l'avons mis en correlation avec la resistance au transfert de charge ([R.sub.tc]) obtenue a partir des analyses de SIE. [Traduit par la Redaction] Mots-cles: greffage electrochimique, sels de naphtyldiazonium, film multicouche, recouvrement de surface, resistance au transfert de charge., 1. Introduction Indium tin oxide (LTO) is an important n-type transparent conductive oxide (TCO) having wide applications in several optoelectronic devices such as organic light-emitting diodes, (1-3) photovoltaics, (4-6) solar [...]

Non-stoichiometric lead free polycrystalline Sr0.8Sn0.2Bi1.75Sm0.25Nb2O9 (SSBSN) ferroelectric ceramics were synthesized through conventional solid step route method by incorporating ball milling and microwave sintering method. X-ray diffraction along with the Rietveld refinement technique confirms the single-phase orthorhombic structure with A21 crystal symmetry. Additionally, the short-range ordering was confirmed by Raman spectroscopy. Doping induced crystallite size and strain were further calculated from the Williamson-Hall plot, which comes around 150 nm and 1.48 × 10–3 respectively. A plate like morphology with an average grain size of 0.41 μm was confirmed by scanning electron microscopy (SEM). A diffuse type ferroelectric to paraelectric phase transition was recorded at 395 °C, mostly arising due to structural heterogeneity at the inter-ferroelectric phase boundary. The temperature and frequency-dependent dielectric measurement of SSBSN ceramic reveal a Maxwell–Wagner relaxation, with prominent dielectric loss in a low frequency regime perhaps due to the generation of leakage current in the SSBSN system. Frequency dependent ac conductivity indicates the polaron assisted hopping mechanism in SSBSN, which further obeys Jonscher’s formulation. The intra and intergranular contributions to impedance in SSBSN ceramics were probed by the complex impedance spectroscopy (CIS) technique. A non-Debye type relaxation mechanism in SSBSN ceramics was indicated by the Cole–Cole plot, whereas the conduction mechanism and transport properties were briefly studied using modulus spectroscopy. [ABSTRACT FROM AUTHOR]

This study investigates the impacts of structure and composition on the optical and electronic properties of a series of pyridinium-based bismuth iodide complexes. Organic substrates with various functional groups, such as 4-aminopyridine (4-Ampy), 4-methylpyridine (4-Mepy), 4-dimethylaminopyridine (4-Dmapy), and 4-pyridinecarbonitrile (4-CNpy) with different electron-donating and electron-withdrawing groups at the para position of the pyridine ring were employed. Crystallographic analysis reveals various bismuth iodide structures, including 1D chains and discrete 0D motifs. The optical band gap of these materials, identified via diffuse reflectance spectroscopy (DRS) and verified with density functional theory (DFT) calculations, is influenced by the crystal packing and stabilising interactions. Through a comprehensive analysis, including Hirshfeld surface (HS) and void assessment, the study underscores the influence of noncovalent intermolecular interactions on crystal packing. Spectroscopic evaluations provide insights into electronic interactions, elucidating the role of electron donor and acceptor substituents within the lattice. Thermogravimetric differential thermal analysis (TG–DTA) indicates structural stability up to 250 °C. Linear sweep voltammetry (LSV) reveals significant conductivity in the range of 10–20 mS per pixel at 298.15 K. X-ray absorption spectroscopy (XAS) at the Bi L3 edge indicates a similar oxidation state and electronic environment across all samples, underscoring the role of bismuth centres surrounded by iodides. [ABSTRACT FROM AUTHOR]

This study investigates the impacts of structure and composition on the optical and electronic properties of a series of pyridinium-based bismuth iodide complexes. Organic substrates with various functional groups, such as 4-aminopyridine (4-Ampy), 4-methylpyridine (4-Mepy), 4-dimethylaminopyridine (4-Dmapy), and 4-pyridinecarbonitrile (4-CNpy) with different electron-donating and electron-withdrawing groups at the para position of the pyridine ring were employed. Crystallographic analysis reveals various bismuth iodide structures, including 1D chains and discrete 0D motifs. The optical band gap of these materials, identified via diffuse reflectance spectroscopy (DRS) and verified with density functional theory (DFT) calculations, is influenced by the crystal packing and stabilising interactions. Through a comprehensive analysis, including Hirshfeld surface (HS) and void assessment, the study underscores the influence of noncovalent intermolecular interactions on crystal packing. Spectroscopic evaluations provide insights into electronic interactions, elucidating the role of electron donor and acceptor substituents within the lattice. Thermogravimetric differential thermal analysis (TG-DTA) indicates structural stability up to 250 °C. Linear sweep voltammetry (LSV) reveals significant conductivity in the range of 10-20 mS per pixel at 298.15 K. X-ray absorption spectroscopy (XAS) at the Bi L 3 edge indicates a similar oxidation state and electronic environment across all samples, underscoring the role of bismuth centres surrounded by iodides.