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The crystal structures, elastic and anisotropic properties of CH3NH3BX3 (B = Sn, Pb; X = Br, I) compounds as solar cell absorber layers are investigated by the first-principles calculations. The type and strength of chemical bond B-X are found to determine the elastic properties. B-X bonds and the organic cations are therefore crucial to the functionalities of such absorbers. The bulk, shear, Young's modulus ranges from 12 to 30 GPa, 3 to 12 GPa, and 15 to 37 GPa, respectively. Moreover, the interaction among organic and inorganic ions would have negligible effect for elastic properties. The B/G and Poisson's ratio show it would have a good ductile ability for extensive deformation as a flexible/stretchable layer on the polymer substrate. The main reason is attributed to the low shear modulus of such perovskites. The anisotropic indices AU, AB AG, A1, A2, and A3 show ABX3 perovskite have very strong anisotropy derived from the elastic constants, chemical bonds, and symmetry.

The crystal structures are successfully established for tetragonal and orthorhombic CH3NH3PbX3 (X = I and Br). The equilibrium lattice parameters are computed by the DFT+D2 method, and the results are compared to experimental values. The band dispersions and electronic densities of states are calculated by HSE06, showing that their band gaps are in the range from 1.63 to 2.3 eV. Although the calculated dielectric functions of MAPbX3 compounds are similar to other semiconductors, the absorption spectra of their bulk crystals are drifted away from visible light spectrum. The effective mass tensors of holes and electrons are also evaluated in three principal directions at the Γ point. The anisotropies in the effective masses of the hole and electron are illustrated for two orthorhombic phases.

(6S)-3-Methylene-6-methyl-1,4-dioxane-2,5-dione was synthesized from L-lactide and used as the dienophile to prepare spiro[6-methyl-1,4-dioxane-2,5-dione-3,2'-bicyclo[2.2.1]hept[5]ene] via an exoselective and diastereofacial-selective Diels-Alder reaction. Polymerizations of this bifunctional lactide derivative were successfully carried out under ring-opening and ring-opening metathesis polymerization conditions to yield high molecular weight and high Tg polymers. We further demonstrated that by incorporating a small percentage of spiro[6-methyl-1,4-dioxane-2,5-dione-3,2'-bicyclo[2.2.1]hept[5]ene] into poly(1,5-cyclooctadiene) and copolymerizing it with DL-lactide, novel polymeric alloys of PLA can be created that have tremendous improvements in toughness over PLA and the corresponding binary blend of PLA and poly(1,5-cyclooctadiene).

In this work, we report the design, fabrication, and characterization of novel biochemical sensors consisting of nanoscale grooves and slits milled in a metal film to form two-arm, three-beam, planar plasmonic interferometers. By integrating thousands of plasmonic interferometers per square millimeter with a microfluidic system, we demonstrate a sensor able to detect physiological concentrations of glucose in water over a broad wavelength range (400-800 nm). A wavelength sensitivity between 370 and 630 nm/RIU (RIU, refractive index units), a relative intensity change between ~10(3) and 10(6) %/RIU, and a resolution of ~3 × 10(-7) in refractive index change were experimentally measured using typical sensing volumes as low as 20 fL. These results show that multispectral plasmonic interferometry is a promising approach for the development of high-throughput, real-time, and extremely compact biochemical sensors.