Temperature-Induced Large Broadening and Blue Shift in the Electronic Band Structure and Optical Absorption of Methylammonium Lead Iodide Perovskite

The power conversion efficiency of hybrid halide perovskite solar cells is profoundly influenced by the operating temperature. Here we investigate the temperature influence on the electronic band structure and optical absorption of cubic CH₃NH₃PbI₃ from first-principles by accounting for both the electron–phonon interaction and thermal expansion. Within the framework of density functional perturbation theory, the electron–phonon coupling induces slightly enlarged band gap and strongly broadened electronic relaxation time as temperature increases. The large broadening effect is mainly due to the presence of cation organic atoms. Consequently, the temperature-dependent absorption peak exhibits blue-shift position, decreased amplitude, and broadened width. This work uncovers the atomistic origin of temperature influence on the optical absorption of cubic CH₃NH₃PbI₃ and can provide guidance to design high-performance hybrid halide perovskite solar cells at different operating temperatures

Test information curves.

<p>Ability signifies knowledge, attitude and behavior with respect to nutrition and food safety, estimated using the maximum-likelihood method. Ability in the item response theory model practically (though not exclusively) ranged from −3 to +3. The test information of knowledge dimension reached a peak when the ability was between 0 and 1; this indicates that the measurement exhibited highest discriminative power among students with moderate ability with respect to nutrition and food safety knowledge. By contrast, this questionnaire exhibited highest discriminative power among students with limited ability with respect to attitude and behavior.</p

Temporal characteristics of the variance curve of responses to different contrasts.

<p><i>A</i>: The variance curve of a typical cell. Optimal latency (T_optimal) is given by the peak of the curve. Peak width of the curve was defined as the time difference between T_decay and T_develop at which the variance reached half of the peak magnitude. <i>B</i>: The distribution of the optimal latencies of a population of neurons (n = 101). <i>C</i>: The distribution of the peak width. In both histograms, the mean is indicated by an arrow. <i>D</i>: Scatter plot showing the significant correlation between the optimal latency and peak width of the variance curves.</p

Illustration of the “fragmentation" technique we proposed for improving the performance of GPU.

<p>Illustration of the “fragmentation" technique we proposed for improving the performance of GPU.</p

Research process flow chart.

<p>Research process flow chart.</p

Syntheses, structures, magnetic, and luminescent properties of five lanthanide-based MOFs with <i>p</i>-phenylenediamine-tetraacetic acid ligand

<div><p>Five new isomorphous metal–organic frameworks, {[Ln(PhDTA)_0.5(H₂PhDTA)_0.5(H₂O)₃]·H₂O}_n [Ln = Pr (<b>1</b>), Sm (<b>2</b>), Eu (<b>3</b>), Gd (<b>4</b>), Tb (<b>5</b>)], have been synthesized under solvothermal conditions based on <i>p</i>-phenylenediamine-N,N,N′,N′-tetraacetic acid (H₄PhDTA). Compounds <b>1–5</b> were characterized by infrared spectra, thermogravimetric analyses and single-crystal X-ray diffraction. Compounds <b>1–5</b> crystallize in the monoclinic system with space group of <i>P</i>2₁/c and have 3-D framework structures. The H₂PhDTA²⁻ and H₂PhDTA⁴⁻ ions exhibit different tetradentate and bidentate modes to connect with lanthanide ions, respectively. The solid-state luminescence of <b>5</b> and magnetism of <b>4</b> were investigated further.</p></div

Silver-Catalyzed Intermolecular [3 + 2]/[5 + 2] Annulation of <i>N</i>‑Arylpropiolamides with Vinyl Acids: Facile Synthesis of Fused 2<i>H</i>‑Benzo[<i>b</i>]azepin-2-ones

A silver-catalyzed oxidative intermolecular [3 + 2]/[5 + 2] annulation of <i>N</i>-arylpropiolamides with 4-vinyl acids for producing fused 2<i>H</i>-benzo­[<i>b</i>]­azepin-2-ones is described. This radical-mediated annulation reaction features broad substrate scope and excellent selectivity, and enables the formation of three new C–C bonds through oxidative decarboxylation, [3 + 2]/[5 + 2] annulations, and C­(sp²)-H functionalization cascades. Employing this silver-catalyzed oxidative strategy, common terminal alkynes were successfully converted into cyclopentenes via intermolecular [3 + 2] annulation

The speedup of the GPU-accelerated motif search over the original version.

<p>“w" stands for motif width.</p

Contrast responses under stimulus contrasts distributing in different ranges.

<p><i>A</i>: An example cell. Data from different ranges of contrast distributions were plotted with different symbols: □ <b>Full</b> for full range of contrast (10% to 90%), ▪ <b>Low</b> for low range (10% to 50%), ▴ <b>Medium</b> for medium range (30% to 70%), • <b>High</b> for high range (50% to 90%). <i>B</i>: The mean response of the 33 cells to 50% contrast decreased when the mean of the contrast range increased. The responses were normalized to the maximal response among the responses of each neuron to the 50% contrast contained in the three stimulus contrast ranges. <i>C</i>: The mean <i>C₅₀</i> of the contrast response function increased with the increase in the mean of the contrast range when fitted with <i>Equation</i> (1) (holding <i>n</i> and <i>R_max</i> constant). <i>D</i>: The mean <i>R_max</i> of contrast response function decreased with the increase in the mean of the contrast range when fitted with <i>Equation</i> (1) (holding <i>n</i> and <i>C₅₀</i> constant) (see Text for details). Note that the data presented in <i>B</i>, <i>C</i>, and <i>D</i> are the mean ± SD (n = 33), not the mean ± s.e.m.</p

Item characteristic curves.

<p>Each Item characteristic curve describes the item-specific relationship between the ability level (X-axis) and probability of the ‘correct’ response (Y-axis). Ability in the item response theory model practically (though not exclusively) ranged from −3 to +3. The difficulty parameter is the point on the ability scale that corresponds to a probability of a correct response of 50%. The discrimination parameter is the slope of each curve. For Likert-type attitude and practice items, polytomous item response model were applied (multiple curves within a single figure, each curve stands for the relationship between ability and probability of a certain response).</p