Crystal Structure and Band Gap Engineering in Polyoxometalate-Based Inorganic–Organic Hybrids

Roy, Soumyabrata; Sarkar, Sumanta; Pan, Jaysree; Waghmare, Umesh V.; Dhanya, R.; Narayana, Chandrabhas; Peter, Sebastian C.

doi:10.1021/acs.inorgchem.5b02718

Cited by 27 publications

(17 citation statements)

References 60 publications

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“…The band gap values exhibit a general increase with the decrease of quantum well thickness (or the index n), owning to the increase of quantum and dielectric confinement. 39 The band gap deviations in the PPCM from the PSCM samples should be explained by multiple mechanisms including the disordered states near the band edges originating from the crystalline impurities, 40 structural asymmetry from crystal orientations, 41 and edge state contributions to the diversity of electronic band structures. 42 We further compared the PL spectra of PPCM and PSCM samples in Figure 3d,e.…”

Section: Resultsmentioning

confidence: 99%

Quasi-Two-Dimensional Halide Perovskite Single Crystal Photodetector

et al. 2018

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The robust material stability of the quasi-two-dimensional (quasi-2D) metal halide perovskites has opened the possibility for their usage instead of three-dimensional (3D) perovskites. Further, devices based on large area single crystal membranes have shown increasing promise for photoelectronic applications. However, growing inch-scale quasi-2D perovskite single crystal membranes (quasi-2D PSCMs) has been fundamentally challenging. Here we report a fast synthetic method for synthesizing inch-scale quasi-2D PSCMs, namely (CHNH) (CHNH) PbI (index n = 1, 2, 3, 4, and ∞), and demonstrate their application in a single-crystal photodetector. A quasi-2D PSCM has been grown at the water-air interface where spontaneous alignment of alkylammonium cations and high chemical potentials enable uniform orientation and fast in-plane growth. Structural, optical, and electrical characterizations have been conducted as a function of quantum well thickness, which is determined by the index n. It is shown that the photodetector based on the quasi-2D PSCM with the smallest quantum well thickness ( n = 1) exhibits a strikingly low dark current of ∼10 A, higher on/off ratio of ∼10, and faster response time in comparison to those of photodetectors based on quasi-2D PSCMs with larger quantum well thickness ( n > 1). Our study paves the way toward the merging the gap between single crystal devices and the emerging quasi-2D perovskite materials.

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Section: Resultsmentioning

confidence: 99%

Quasi-Two-Dimensional Halide Perovskite Single Crystal Photodetector

et al. 2018

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“…A summary of the crystallographic data is provided in Table . The specific descriptions of the synthesis of compounds 1 – 3 , the single-crystal X-ray crystallography and the preparation of the modified electrodes, the analyses of the bond valence sum (BVS), the Fourier-transform infrared (FT-IR) spectra (Table S1), the powder X-ray diffraction (PXRD), the N 2 sorption isotherm, and the reasons for the election of the building blocks are provided in the Supporting Information.…”

Section: Resultsmentioning

confidence: 99%

Polyoxometalate Metal–Organic Frameworks: Keggin Clusters Encapsulated into Silver-Triazole Nanocages and Open Frameworks with Supercapacitor Performance

et al. 2019

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To investigate the relationship between the structures of polyoxometalate host–guest materials and their energy-storage performance, three novel polyoxometalate-based metal–organic compounds, [Ag10(C2H2N3)8][HVW12O40], [Ag10(C2H2N3)6][SiW12O40], and [Ag(C2H2N3)][Ag12(C2H2N3)9][H2BW12O40] are synthesized by a one-step hydrothermal method and further confirmed by single-crystal X-ray diffraction analyses and other numerous characterization techniques. In compound [Ag10(C2H2N3)8][HVW12O40], the Keggin clusters are intersected into channels formed by a 3D open metal–organic framework. In contrast, in compounds [Ag10(C2H2N3)6][SiW12O40] and [Ag(C2H2N3)][Ag12(C2H2N3)9][H2BW12O40], the Keggin clusters are encapsulated into silver-triazole metal–organic nanocages to construct core–shell structures, which are further fused together by covalent bonds to form 3D polyoxometalate-based metal–organic frameworks. The electrochemical properties of three compound-based electrodes are estimated by cyclic voltammetry, galvanostatic charge–discharge, electrochemically active surface area, and electrochemical impedance spectroscopy. The results of the electrochemical performance tests indicate that these compounds possess high specific capacitance and cycling stability, especially [Ag10(C2H2N3)8][HVW12O40], showing a specific capacitance of 93.5 F g–1, which is higher than that of many other polyoxometalate-based electrode materials. A possible mechanism of the electrochemical performance is explored, which is mainly related to the redox capacity of polyoxometalate, the electrochemically active surface area, the electrochemical impedance spectroscopy, and the microstructures of polyoxometalate-based metal–organic frameworks.

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“…In this study, the experimental evidence to solve the crystal structure solution was inappropriate and that to resolve the position of hydrogen atoms in this material is almost impossible. The first-principle based structural optimization calculation is a useful tool to pinpoint the hydrogen position in such situation [35]. The experiment captured the positions of all the oxygen in the H 2 V 3 O 8 crystal successfully but inept to identify the oxygen belonging to the intercalated water.…”

Section: Theoretical Calculation Of H 2 V 3 Omentioning

confidence: 99%

Preparation, structure study and electrochemistry of layered H2V3O8 materials: High capacity lithium-ion battery cathode

Sarkar

Bhowmik

Pan

et al. 2016

Journal of Power Sources

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The present study explores H 2 V 3 O 8 as high capacity cathode material for lithium-ion batteries (LIB's). Despite having high discharge capacity, H 2 V 3 O 8 material suffers from poor electrochemical stability for prolonged cycle life. Ultra-long H 2 V 3 O 8 nanobelts with ordered crystallographic patterns are synthesizedviaa hydrothermal process to mitigate this problem. The growth of the crystal is facile along [001] direction, and the most common surface is (001) as suggested by Wulff construction study.Electrochemical performance of H 2 V 3 O 8 cathode is tested against Li/Li + at various current rates.At 50 mA g-1 current rate, it delivers adischarge capacity of 308 mAh g-1 , whereas, at 3000 mA g-1 , an initial discharge capacity of 144 mAh g-1 is observed and stabilized at 100 mAh g-1 till 500 cycles. Further, the density functional theory (DFT) based simulations study of both the pristine and lithiated phase of H 2 V 3 O 8 cathode materials is undertaken. DFT study reveals the presence of hydrogen as hydroxyl unit in the framework of the host. In correlation, the magnetic property of vanadium atoms is examined in detail with through partial density of states (PDOS) calculation during three stage lithiation processes and evaluating various potential steps involved in lithium insertion.

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Crystal Structure and Band Gap Engineering in Polyoxometalate-Based Inorganic–Organic Hybrids

Cited by 27 publications

References 60 publications

Quasi-Two-Dimensional Halide Perovskite Single Crystal Photodetector

Quasi-Two-Dimensional Halide Perovskite Single Crystal Photodetector

Polyoxometalate Metal–Organic Frameworks: Keggin Clusters Encapsulated into Silver-Triazole Nanocages and Open Frameworks with Supercapacitor Performance

Preparation, structure study and electrochemistry of layered H2V3O8 materials: High capacity lithium-ion battery cathode

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