Indian Association for the Cultivation of Science

About: Indian Association for the Cultivation of Science is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Excited state & Catalysis. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

Tips and Twists in Making High Photoluminescence Quantum Yield Perovskite Nanocrystals

Abstract: Making nanocrystals in a reaction flask is always exciting. This is even more fun with visible light-emitting nanocrystals. After the workhorse CdSe,(1) CsPbX3 (X = Cl, Br, and I) perovskite nanocrystals emerged as the next all-visible color tunable emitters in nanodimensions.(2) While the synthesis of both of these types of semiconductor nanocrystals employed colloidal hot injection reactions, but perovskite nanocrystals showed unprecedented high photoluminescence quantum yield (PLQY). Hence, these nanocrystals remained in the forefront of current research and are considered as an efficient lighting material for energy conversion. However, the root of the performance in any kind of lighting application remains the quality of the material, which in turn depends on the synthetic strategy in the reaction flask. During the last four years, significant improvements have been achieved in optimizing the synthesis and obtaining near-unity PLQYs for all blue, green, and red emitting perovskite nanocrystals. The high-temperature synthetic approach, originally developed by Kovalenko et al.,(2) remained the benchmark protocol for obtaining these high-quality nanocrystals. This has been further modified, and the reaction chemistry for the formation of all three of these halide perovskite nanocrystals has been widely investigated.(3−11) Analysis of the chronological developments with variations of precursor ratios, ligands, reaction temperature, and also the solvent suggests that each successive modification has a logic behind the optimization of the reaction. This also helps in formulating the precise reaction parameters for obtaining the near-unity PLQY for all three CsPbX3 (X = Cl, Br, and I) nanocrystals in a reaction flask. Compiling all these developments, the step-by-step progress of reactions in the synthesis of these perovskite nanocrystals, is discussed in this Viewpoint. Some synthesis tips and also some tricks for avoiding phase change or quenching of photoluminescence (PL) of these nanocrystals are also discussed.

Templating Effects and Optical Characterization of Copper (II) Phthalocyanine Nanocrystallites Thin Film: Nanoparticles, Nanoflowers, Nanocabbages, and Nanoribbons

Abstract: The recent emergence of molecular ultrathin films as candidates for functional electronic materials and photo catalyst has prompted numerous investigations on their crystalline structure and thin film formation This article describes the role of the effect of the nature of substrate and substrate temperatures in molecular organization of copper (II) phthalocyanine (CuPc) on gold coated quartz substrates using conventional vapor deposition at high vacuum (∼10-6 Torr) Surprisingly, the 100 nm thick CuPc films on the quartz substrates are as highly ordered as on the polycrystalline gold-coated quartz substrates Importantly, the molecular orientation in the two cases is radically different Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) observations of the ordered crystalline films indicated that domains are grown from the bottom to the top of the film and are densely packed with little grain boundary X-ray diffraction (XRD) pattern shows a sharp intense pea

Functionalized graphene and graphene oxide solution via polyacrylate coating

Abstract: Water soluble graphene with various chemical- and biofunctionalities is essential for their different applications. However, exfoliated graphenes are insoluble in water and water soluble graphene oxide precipitate if they are chemically reduced to graphene. We have developed a polyacrylate coating method for graphene oxide and then chemically reduced it into graphene. We found that polyacrylate coating can improve the colloidal stability of both graphene and graphene oxide. The coated graphene has been characterized using XPS, FTIR, XRD and micro-Raman spectroscopy. The primary amine present on the coating backbone has been used to derive glucose functionalized water soluble graphene. Various other functional graphenes can be anticipated from the polyacrylate coated graphene.

Model Compounds for Iron Proteins. Structures and Magnetic, Spectroscopic, and Redox Properties of Fe(III)M(II) and [Co(III)Fe(III)](2)O Complexes with (m-Carboxylato)bis(m-phenoxo)dimetalate and (m-Oxo)diiron(III) Cores.

Abstract: A series of heterobimetallic complexes of the type [FeIIIMIIL(μ-OAc)(OAc)(H2O)](ClO4)·nH2O (2−5) and [{FeIIICoIIIL(μ-OAc)(OAc)}2(μ-O)](ClO4)2·3H2O (6) where H2L is a tetraaminodiphenol macrocyclic ligand and MII = Zn(2), Ni(3), Co(4), and Mn(5) have been synthesized and characterized. The 1H NMR spectrum of 6 exhibits all the resonances between 1 and 12 ppm. The IR and UV−vis spectra of 2−5 indicate that in all the cases the metal ions have similar coordination environments. A disordered crystal structure determined for 3 reveals the presence of a (μ-acetate)bis(μ-phenoxide)−NiIIFeIII core, in which the two metal ions have 6-fold coordination geometry and each have two amino nitrogens and two phenolate oxygens as the in-plane donors; aside from the axial bridging acetate, the sixth coordination site of nickel(II) is occupied by the unidentate acetate and that of iron(III) by a water molecule. The crystal structure determination of 6 shows that the two heterobinuclear CoIIIFeIII units are bound by an Fe−O−...