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11.
Ultrafast Photogenerated Hole Extraction/Transport Behavior in a CH3NH3PbI3/Carbon Nanocomposite and Its Application in a Metal‐Electrode‐Free Solar Cell 下载免费PDF全文
Tao Ye Xi Jiang Dongyang Wan Xingzhi Wang Dr. Jun Xing Prof. Thirumalai Venkatesan Prof. Qihua Xiong Prof. Seeram Ramakrishna 《Chemphyschem》2016,17(24):4102-4109
Aligned and flexible electrospun carbon nanomaterials are used to synthesize carbon/perovskite nanocomposites. The free‐electron diffusion length in the CH3NH3PbI3 phase of the CH3NH3PbI3/carbon nanocomposite is almost twice that of bare CH3NH3PbI3, and nearly 95 % of the photogenerated free holes can be injected from the CH3NH3PbI3 phase into the carbon nanomaterial. The exciton binding energy of the composite is estimated to be 23 meV by utilizing temperature‐dependent optical absorption spectroscopy. The calculated free carriers increase with increasing total photoexcitation density, and this broadens the potential of this material for a broad range of optoelectronics applications. A metal‐electrode‐free perovskite solar cell (power conversion efficiency: 13.0 %) is fabricated with this perovskite/carbon composite, which shows great potential for the fabrication of efficient, large‐scale, low‐cost, and metal‐electrode‐free perovskite solar cells. 相似文献
12.
N. Lee D. Thirumalai 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(4):599-605
The effect of electrostatic interactions on the stretching of DNA is investigated using a simple worm like chain model. In
the limit of small force there are large conformational fluctuations which are treated using a self-consistent variational
approach. For small values of the external force f, we find the extension scales as where is the Debye screening length. In the limit of large force the electrostatic effects can be accounted for within the semiflexible
chain model of DNA by assuming that only small excursions from rod-like conformations are possible. In this regime the extension
approaches the contour length as where f is the magnitude of the external force. The theory is used to analyze experiments that have measured the extension of double-stranded
DNA subject to tension at various salt concentrations. The theory reproduces nearly quantitatively the elastic response of
DNA at small and large values of f and for all concentration of the monovalent counterions. The limitations of the theory are also pointed out.
Received 13 October 1998 and Received in final form 9 June 1999 相似文献
13.
New Scheelite-related solid solutions of the compositions Nax/2Bi1−x/2MoxV1−xO4 (0≤x≤1) and Bi1−x/3 MoxV1−xO4(0≤x≤0.2) have been synthesised by the substitution of Na and Mo at the A and B sites respectively of the ABO4 type ferroelastic BiVO4. The phases were characterised using chemical analysis, powder X-ray diffraction, scanning electron microscopy, EDAX, and Raman spectroscopy. While almost a continuous solid solution is obtained for the series Nax/2Bi1−x/2MoxV1−xO4, the absence of Na at the A-site results only in a narrow stability region for the other series, Bi1−x/3 MoxV1−xO4 where 0≤x≤0.2. Raman spectra of selected samples at room temperature also suggest that vanadium and molybdenum atoms are disordered at the tetrahedral sites. 相似文献
14.
Jeyaraman Selvaraj Nirmalram Duraisamy Tamilselvi Packianathan Thomas Muthiah 《Journal of chemical crystallography》2011,41(6):864-867
Abstract
N 6-benzyladeninium nitrate, (1), C12H12N5 + NO3 − crystallizes in P2 1/c, with a = 15.0035(13), b = 5.3788(5), c = 16.8954(13) ?, β = 107.331(6)°, Z = 4 and N 6-benzyladeninium 3-hydroxy picolinate, (2), C12H12N5 + C6H4NO3 −, crystallizes in P1, with a = 8.3017(4), b = 14.6170(7), c = 14.7909 (8) ?, α = 78.801 (4), β = 81.979 (4),γ = 88.849 (4)°, Z = 4. In both the salts, the cation exists as N(7)H tautomer with protonation at the N3 atom. The dihedral angle of 76.64 (16)° for (1), 67.91(12)° for (cation A) and 68.27 (13)° for (cation B) in (2), between the adenine plane and phenyl ring plane, the distal orientation of the N6 substituent with respect to the imidazole ring and the free N1 position, make these benzyladeninium cations meet all the requirements necessary for cytokinin activity. The crystal structures are stabilized by N–H···N, N–H···O, C–H···O hydrogen bonds and C–H···π stacking interaction between symmetry related benzyladenine molecule. 相似文献15.
Loop formation between monomers in the interior of semiflexible chains describes elementary events in biomolecular folding and DNA bending. We calculate analytically the interior distance distribution function for semiflexible chains using a mean field approach. Using the potential of mean force derived from the distance distribution function we present a simple expression for the kinetics of interior looping by adopting Kramers theory. For the parameters, that are appropriate for DNA, the theoretical predictions in comparison with the case are in excellent agreement with explicit Brownian dynamics simulations of wormlike chain (WLC) model. The interior looping times (tauIC) can be greatly altered in the cases when the stiffness of the loop differs from that of the dangling ends. If the dangling end is stiffer than the loop then tauIC increases for the case of the WLC with uniform persistence length. In contrast, attachment of flexible dangling ends enhances rate of interior loop formation. The theory also shows that if the monomers are charged and interact via screened Coulomb potential then both the cyclization (tauc) and interior looping (tauIC) times greatly increase at low ionic concentration. Because both tauc and tauIC are determined essentially by the effective persistence length [lp(R)] we computed lp(R) by varying the range of the repulsive interaction between the monomers. For short range interactions lp(R) nearly coincides with the bare persistence length which is determined largely by the backbone chain connectivity. This finding rationalizes the efficacy of describing a number of experimental observations (response of biopolymers to force and cyclization kinetics) in biomolecules using WLC model with an effective persistence length. 相似文献
16.
17.
Force-extension curves (FECs), which quantify the response of a variety of biomolecules subject to mechanical force (f), are often quantitatively fit using worm-like chain (WLC) or freely jointed chain (FJC) models. These models predict that the chain extension, x, normalized by the contour length increases linearly at small f and at high forces scale as x ~ (1 - f(-α)), where α = 0.5 for WLC and unity for FJC. In contrast, experiments on single-stranded DNA (ssDNA) show that over a range of f and ionic concentration, x scales as x ~ ln f, which cannot be explained using WLC or FJC models. Using theory and simulations we show that this unusual behavior in FEC in ssDNA is due to sequence-independent polyelectrolyte effects. We show that the x ~ ln f arises because in the absence of force the tangent correlation function, quantifying chain persistence, decays algebraically on length scales on the order of the Debye length. Our theory, which is most appropriate for monovalent salts, quantitatively fits the experimental data and further predicts that such a regime is not discernible in double-stranded DNA. 相似文献
18.
A. Subbiah Pandi D. Velmurugan S. Shanmuga Sundara Raj Hoong‐Kun Fun P. R. Seshadri D. Thirumalai 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(7):821-824
10‐(4‐Fluorophenyl)‐3,3,6,6,9‐pentamethyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione, C24H28FNO2, (I), crystallizes with two crystallographically independent molecules (which differ slightly in conformation), while 10‐(4‐fluorophenyl)‐9‐propyl‐3,3,6,6‐tetramethyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione, C26H32FNO2, (II), crystallizes with one molecule per asymmetric unit. In both structures, the central ring in the acridine moiety is in a sofa conformation, while the outer rings adopt intermediate half‐chair/sofa conformations. The central pyridine ring is orthogonal to the substituted phenyl ring. In both structures, the packing of the crystal is stabilized by C—H?O intermolecular hydrogen bonds. 相似文献
19.
Udhayakumari Duraisamy 《Journal of inclusion phenomena and macrocyclic chemistry》2022,102(5-6):451-476
Journal of Inclusion Phenomena and Macrocyclic Chemistry - Mercury is a frequent, bioaccumulative, extremely toxic pollutant in the environment. Mercury contamination can be accumulated along the... 相似文献
20.