Publications by authors named "Ishita Neogi"

Donor-acceptor (D-A) materials based on butterfly-shaped molecules could inhibit exciton-migration-induced quenching due to molecular twist. To explore this attribute towards beneficial photophysical properties, three novel bipolar acceptor-donor-acceptor (A-D-A) molecules with triphenyl triazine end capping along with substitution ortho to the Tröger's base (TB) scaffold varying from H, Me, and F were explored. The installation of H/Me/F imparted an electron push-pull effect with concomitant maneuvering of photophysical properties.

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Perovskites are hybrid materials containing templating organic linkers and inorganic halides with efficiencies that have superseded the efficiency of silicon-based photovoltaic devices (PVs) in a very short period of 10 years. Nevertheless, low ambient stability due to traps and ion migration caused hysteresis to remain the bottlenecks on the way to achieving higher operational stability with bulk perovskite-based PVs. In this context, herein we highlight the prospects of in situ cross-linking of linkers within the perovskite lattice either mediated by thermal means or attained photochemically that can maneuver the ambient as well as operational stability for enhanced power conversion efficiency for PV applications or could improve the conductivity of this hybrid semiconductor.

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Herein, the synthesis of pyrene conjugated 2,6-di-ortho-tolylpyridine and 2,6-di-para-tolylpyridine structural isomers were achieved efficiently through multicomponent Chichibabin pyridine synthesis reaction. The DFT, TD-DFT and experimental investigations were carried out to investigate the photophysical behaviors of the synthesized novel pyrene-pyridine based isomeric probes. Our studies revealed that, due to the continuous conjugation of the pyrene, pyridine and tolyl moieties, the dihedral angles of the trisubstituents on the central pyridine moiety significantly influences the photophysical properties of the synthesized novel pyrene based fluorescent probes.

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Dioxobimanes, colloquially known as bimanes, are a well-established family of -heterobicyclic compounds that share a characteristic core structure, 1,5-diazabicyclo[3.3.0]octadienedione, bearing two endocyclic carbonyl groups.

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In this work, a new bimetallic Na(I)-Zn(II) metal-organic framework (MOF), formulated as [NaZn(btc)(μ-HCOO)(μ-HO)] () (Hbtc = benzene tricarboxylic acid), and its composite (ZnO@) have been successfully synthesized using solvothermal and mechanochemical solid grinding methods. and ZnO@ were characterized by diffraction [single-crystal X-ray diffraction (XRD) and powder XRD], spectroscopic (ultraviolet-visible diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy), microscopic (transmission electron microscopy), and thermal (thermogravimetric analysis) methods. The surface area and porosity of were determined using a Brunauer-Emmett-Teller analyzer.

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In this manuscript we reveal the formation of bilayered hybrid perovskites of a new lower dimensional perovskite family, (CHMA)(MA)PbI with n = 1-5, with high ambient stability via its crystallization driven self-assembly process. The spun-coated perovskite solution tends to crystallize and undergo phase separation during annealing, resulting in the formation of 2D/3D bilayered hybrid perovskites. Remarkably, this 2D/3D hybrid perovskites possess striking moisture resistance and displays high ambient stability up to 65 days.

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A new broadband-emitting 2 D hybrid organic-inorganic perovskite (CyBMA)PbBr based on highly flexible cis-1,3-bis(methylaminohydrobromide)cyclohexane (CyBMABr) core has been designed, synthesized, and investigated, highlighting the effects of stereoisomerism of the templating cation on the formation and properties of the resulting perovskite. The new 2 D material has high exciton binding energy of 340 meV and a broad emission spanning from 380 to 750 nm, incorporating a prominent excitonic band and a less intense broad peak at room temperature. Significant changes in the photoluminescence (PL) spectrum were observed at lower temperatures, showing remarkable enhancement in the intensity of the broadband at the cost of excitonic emission.

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Ultrafast spin manipulation for opto-spin logic applications requires material systems that have strong spin-selective light-matter interaction. Conventional inorganic semiconductor nanostructures [for example, epitaxial II to VI quantum dots and III to V multiple quantum wells (MQWs)] are considered forerunners but encounter challenges such as lattice matching and cryogenic cooling requirements. Two-dimensional halide perovskite semiconductors, combining intrinsic tunable MQW structures and large oscillator strengths with facile solution processability, can offer breakthroughs in this area.

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Tröger's bases (TBs) functionalized with carbazoles (TB-Czs) and phosphine oxides (TB-POs) were designed and synthesized as host materials for application in phosphorescent organic light-emitting diodes. The TB scaffold is shown to impart thermal stability with high Tg values (171-211 °C) as well as high triplet energies in the range of 2.9-3.

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