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Investigates the dynamic distribution of charge carriers in organic quantum-well light-emitting diodes (QWLED) using time-resolved electroluminescence (EL). Similarity of transient EL spectra to traditional LED; Transit time for electron corresponding to electron mobility; Transient characteristics of carrier transport.

Using the tensor renormalization group method based on the higher-order singular value decomposition, we have studied the phase transitions of the five-state clock model on the square lattice. The temperature dependence of the specific heat indicates the system has two phase transitions, as verified clearly by the correlation function at three representative temperatures. By calculating the magnetic susceptibility, we obtained only the upper critical temperature as Tc2 = 0.9565(7). Investigating the fixed-point tensor, we precisely locate the transition temperatures at Tc1 = 0.9029(1) and Tc2 = 0.9520(1), consistent well with the Monte Carlo and the density matrix renormalization group results. [ABSTRACT FROM AUTHOR]

We develop coarse-graining tensor renormalization group algorithms to compute physical properties of two-dimensional lattice models on finite periodic lattices. Two different coarse-graining strategies, one based on the tensor renormalization group and the other based on the higher-order tensor renormalization group, are introduced. In order to optimize the tensor network model globally, a sweeping scheme is proposed to account for the renormalization effect from the environment tensors under the framework of second renormalization group. We demonstrate the algorithms by the classical Ising model on the square lattice and the Kitaev model on the honeycomb lattice, and show that the finite-size algorithms achieve substantially more accurate results than the corresponding infinite-size ones. [ABSTRACT FROM AUTHOR]

We investigate the 2- and 3-state ferromagnetic Potts models on the simple cubic lattice using the tensor renormalization group method with higher-order singular value decomposition (HOTRG). HOTRG works in the thermodynamic limit, where we use the Zq symmetry of the model, combined with a new measure for detecting the transition, to improve the accuracy of the critical point for the 2-state model by two orders of magnitude, obtaining Tc = 4.51152469(1). The 3-state model is far more complex, and we improve the overall understanding of this case by calculating its thermodynamic quantities with high accuracy. Our results verify that the first-order nature of the phase transition and the HOTRG transition temperature benchmarks the most recent Monte Carlo result. [ABSTRACT FROM AUTHOR]

In the title compound, CH6N3S+·C6H2N3O7−·H2O, the components are linked by a number of N—H...O and O—H...O hydrogen bonds into a complex three-dimensional network. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title compound, C6H8N3O+·C7H5O6S−·H2O, cations, anions and water molecules are linked by a number of C/N/O—H...O and N—H...N hydrogen bonds into a three-dimensional network. [ABSTRACT FROM AUTHOR]

In the title compound, C5H7N2+·C6H4NO2−·C5H6N2, the components are linked into a two-dimensional network through N—H...O and N—H...N hydrogen bonds. Adjacent layers are further linked by C—H...O hydrogen bonds, forming a three-dimensional framework. [ABSTRACT FROM AUTHOR]

Inverted polymer solar cells with molybdenum oxide (MoO3) as an anode buffer layer and different metals (Al or Ag) as anodes are studied. It is found that the inverted cell with a top Ag anode demonstrates enhanced charge collection and higher power conversion efficiency (PCE) compared to the cell with a top Al anode. An 18% increment of PCE is obtained by replacing Al with Ag as the top anode. Further studies show that an interfacial dipole pointing from MoO3 to Al is formed at MoO3/Al interfaces due to electron transfer from Al to MoO3 while this phenomenon cannot be observed at MoO3/Ag interfaces. It is speculated that the electric field at the MoO3/Al interface would hinder hole extraction, and hence reduce the short-circuit current. [ABSTRACT FROM AUTHOR]

We propose an eigenoperator scheme to study the lattice model of interacting spinless fermions at half filling and show that this model possesses a hidden form of reflection positivity in its Majorana fermion representation. Based on this observation, we prove rigourously that the ground state of this model is either unique or doubly degenerate if the lattice size N is even, and is always doubly degenerate if N is odd. This proof holds in all dimensions with arbitrary lattice structures. [ABSTRACT FROM AUTHOR]

A quasi-rectangular waveguide polymer Mach-Zehnder (M-Z) electro-optic (EO) modulator based on an organic/ inorganic hybrid material with thermal bias control is fabricated and demonstrated. Linear bias for the modulator is obtained through thermo-optic effect. The optical output is adjusted by changing phase difference between the two arms of the M-Z interferometer. A power consumption of 16.1mW for ?? phase change is observed owing to the application of silica cladding. This approach is proved to be effective to suppress direct current drift in polymer EO modulators. [ABSTRACT FROM AUTHOR]

We propose a generalized Lanczos method to generate the many-body basis states of quantum lattice models using tensor-network states (TNS). The ground-state wave function is represented as a linear superposition composed from a set of TNS generated by Lanczos iteration. This method improves significantly the accuracy of the tensor-network algorithm and provides an effective way to enlarge the maximal bond dimension of TNS. The ground state such obtained contains significantly more entanglement than each individual TNS, reproducing correctly the logarithmic size dependence of the entanglement entropy in a critical system. The method can be generalized to non-Hamiltonian systems and to the calculation of low-lying excited states, dynamical correlation functions, and other physical properties of strongly correlated systems. [ABSTRACT FROM AUTHOR]

We investigate the critical behavior and the duality property of the ferromagnetic q-state clock model on the square lattice based on the tensor-network formalism. From the entanglement spectra of local tensors defined in the original and dual lattices, we obtain the exact self-dual points for the model with q ≤ 5 and approximate self-dual points for q ≥ 6. We calculate accurately the lower and upper critical temperatures for the six-state clock model from the fixed-point tensors determined using the higher-order tensor renormalization group method and compare with other numerical results. [ABSTRACT FROM AUTHOR]

We introduce a slave-fermion formulation in which to study the charge dynamics of the half-filled Hubbard model on the square lattice. In this description, the charge degrees of freedom are represented by fermionic holons and doublons and the Mott-insulating characteristics of the ground state are the consequence of holon–doublon bound-state formation. The bosonic spin degrees of freedom are described by the antiferromagnetic Heisenberg model, yielding long-ranged (Néel) magnetic order at zero temperature. Within this framework and in the self-consistent Born approximation, we perform systematic calculations of the average double occupancy, the electronic density of states, the spectral function and the optical conductivity. Qualitatively, our method reproduces the lower and upper Hubbard bands, the spectral-weight transfer into a coherent quasiparticle band at their lower edges and the renormalisation of the Mott gap, which is associated with holon–doublon binding, due to the interactions of both quasiparticle species with the magnons. The zeros of the Green function at the chemical potential give the Luttinger volume, the poles of the self-energy reflect the underlying quasiparticle dispersion with a spin-renormalised hopping parameter and the optical gap is directly related to the Mott gap. Quantitatively, the square-lattice Hubbard model is one of the best-characterised problems in correlated condensed matter and many numerical calculations, all with different strengths and weaknesses, exist with which to benchmark our approach. From the semi-quantitative accuracy of our results for all but the weakest interaction strengths, we conclude that a self-consistent treatment of the spin-fluctuation effects on the charge degrees of freedom captures all the essential physics of the antiferromagnetic Mott–Hubbard insulator. We remark in addition that an analytical approximation with these properties serves a vital function in developing a full understanding of the fundamental physics of the Mott state, both in the antiferromagnetic insulator and at finite temperatures and dopings. [ABSTRACT FROM AUTHOR]

We propose a modified spin-wave theory to study the 1/3 magnetization plateau of the antiferromagnetic Heisenberg model on the kagome lattice. By the self-consistent inclusion of quantum corrections, the 1/3 plateau is stabilized over a broad range of magnetic fields for all spin quantum numbers S. The values of the critical magnetic fields and the widths of the magnetization plateaus are fully consistent with the recent numerical results from exact diagonalization and infinite projected entangled paired states. [ABSTRACT FROM AUTHOR]

The short-circuit current of polymer solar cells based on a PCPDTBT:PC71BM blend is substantially increased by using a processing additive. It is found that the significant geminate recombination in the PCPDTBT:PC71BM blend film is dramatically suppressed by using a processing additive which can produce a nanoscale PCPDTBT and PC71BM phase separation. The processing additive-induced aggregation of PCPDTBT polymer chains and PC71BM molecules can give rise to a driving force for the separation of charge-transfer states at the donor/acceptor interfaces into the free charge carriers and thus geminate recombination is suppressed. [ABSTRACT FROM AUTHOR]