Size- and Halide-Dependent Auger Recombination in Lead Halide Perovskite Nanocrystals

Lead halide perovskite nanocrystals (NCs) hold strong promise for a variety of light-harvesting, emitting, and detecting applications, all of which, however, could be complicated by multicarrier Auger recombination. Therefore, complete documentation of the size- and composition-dependent Auger recombination rates of these NCs is highly desirable, as it can guide system design in many applications. Herein we report the synthesis and Auger measurements of monodisperse APbX₃ (A=Cs and FA; X=Cl, Br, and I) NCs in an extensive size range (ca. 3–9 nm). The biexciton Auger lifetime of all the NCs scales linearly with the NC volume. The scaling coefficient is virtually independent of the cation but rather depends sensitively on the anion, and is 0.035, 0.085, and 0.142 ps nm⁻³ for Cl, Br, and I, respectively. In all of these nanocrystals the Auger recombination is much faster than in standard CdSe and PbSe NCs (ca. 1 ps nm⁻³).     

A partial proximal point algorithm for nuclear norm regularized matrix least squares problems

We introduce a partial proximal point algorithm for solving nuclear norm regularized matrix least squares problems with equality and inequality constraints. The inner subproblems, reformulated as a system of semismooth equations, are solved by an inexact smoothing Newton method, which is proved to be quadratically convergent under a constraint non-degeneracy condition, together with the strong semi-smoothness property of the singular value thresholding operator. Numerical experiments on a variety of problems including those arising from low-rank approximations of transition matrices show that our algorithm is efficient and robust.     

From n-alkane to polyacetylene on Cu (110): Linkage modulation in chain growth

Direct coupling or transformation of inert alkanes based on the selective C–H activation is of great importance for both chemistry and chemical engineering. Here, we report the coupling of polyenes that are transformed from n-dotriacontane (n-C₃₂H₆₆)through on-surface cascade dehydrogenation on Cu (110) surface, leading to the formation of polyacetylene (PA). Three distinct linkages have been resolved by scanning tunneling microscope (STM) and noncontact atomic force micros...     

(Ti/ZnO)N成分调制纳米多层膜的结构与透光导电性研究

采用射频(RF)和单极中频直流脉冲磁控溅射方法,在玻璃基板上制备了(Ti/ZnO)_N成分调制纳米多层膜,并研究了调制周期数对其结构及透光导电性能的影响。通过X射线衍射、拉曼光谱、原子力显微镜、紫外可见吸收光谱以及霍尔效应测试结果表明:(Ti/ZnO)_N成分调制纳米多层膜以(002)取向的纤锌矿型ZnO结构为主,具有明确的成分调制结构,各Ti层和各ZnO层厚度均匀连续,各界面平整且无明显扩散。在可见光范围的平均透光率大于85%,电阻率最小可达到2.63×10^-2 Ω·cm。