Photoluminescence Properties of CdSe/ZnS Quantum Dot Donor-Acceptor via Plasmon Coupling of Metal Nanostructures and Application on Photovoltaic Devices.

Hybrid nanostructures composed of quantum dots (QDs) and metal nanoparticles (MNS) have gained immense research interest because of their unique optical properties. In optoelectronic applications, quenching and enhancement in QD photoluminescence (PL) are critical parameters. Herein, gold nanoparticles coating a silica layer decorated with quantum dots (AuNPs@SiO2@QDs) are prepared with diverse SiO2 thickness and QD diameter for investigating the exciton-plasmon interaction. This reveals the charge interaction between QDs and AuNPs@SiO2 resulting from different impacts of the Föster energy-transfer process and plasmon resonance enhancement. The variation in both radiative and nonradiative energy-transfer processes in CdSe/ZnS QDs donor-acceptor pairs clarifies the impact of AuNPs@SiO2. In addition, the hybrid structures are plainly incorporated with silicon solar cells, which activated the improvement in the power conversion efficiency (PCE). With the significant tunability of the PL intensity in the visible and near-infrared regions, this hybrid nanostructure provides potential strategies for developing efficient optoelectronics via facile methods.

Polar alignment of Λ-shaped basic building units within transition metal oxide fluoride materials.

A series of pseudosymmetrical structures of formula K10(M2OnF11-n)3X (M = V and Nb, n = 2, X = (F2Cl)1/3, Br, Br4/2,I4/2; M = Mo, n = 4, X = Cl, Br4/2, I4/2) illustrates generation of polar structures with the use of Λ-shaped basic building units (BBUs). For a compound to belong to a polar space group, dipole moments of individual species must be partially aligned. Incorporation of d(0) early transition metal polyhedral BBUs into structures is a common method to create polar structures, owing to the second-order Jahn-Teller distortion these polyhedra contain. Less attention has been spent examining how to align the polar moments of BBUs. To address alignment, we present a study on previously reported bimetallic BBUs and synthesized compounds K10(M2OnF11-n)3X. These materials differ in their (non)centrosymmetry despite chemical and structural similarities. The vanadium compounds are centrosymmetric (space groups P3m1 or C2/m) while the niobium and molybdenum heterotypes are noncentrosymmetric (Pmn21). The difference in symmetry occurs owing to the presence of linear, bimetallic BBUs or Λ-shaped bimetallic BBUs and related packing effects. These Λ-shaped BBUs form as a consequence of the coordination environment around the bridging anion of the metal oxide fluoride BBUs.

Role of hydrogen-bonding in the formation of polar achiral and nonpolar chiral vanadium selenite frameworks.

A series of organically templated vanadium selenites have been prepared under mild hydrothermal conditions. Single crystals were grown from mixtures of VOSO(4), SeO(2), and either 1,4-dimethylpiperazine, 2,5-dimethylpiperazine, or 2-methylpiperazine in H(2)O. Each compound contains one-dimensional [VO(SeO(3))(HSeO(3))](n)(n-) secondary building units, which connect to form three-dimensional frameworks in the presence of 2,5-dimethylpiperazine or 2-methylpiperazine. Differences in composition and both intra-secondary building unit and organic-inorganic hydrogen-bonding between compounds dictate the dimensionality of the resulting inorganic structures. [1,4-dimethylpiperazineH(2)][VO(SeO(3))(HSeO(3))](2) contains one-dimensional [VO(SeO(3))(HSeO(3))](n)(n-) chains, while [2,5-dimethylpiperazineH(2)][VO(SeO(3))(HSeO(3))](2)·2H(2)O contains a three-dimensional [VO(SeO(3))(HSeO(3))](n)(n-) framework. The use of racemic 2-methylpiperazine also results in a compound containing a three-dimensional [VO(SeO(3))(HSeO(3))](n)(n-) framework, crystallizing in the noncentrosymmetric polar, achiral space group Pca2(1) (no. 29), while analogous reactions containing either (R)-2-methylpiperazine or (S)-2-methylpiperazine result in noncentrosymmetric, nonpolar chiral frameworks that crystallize in P2(1)2(1)2 (no. 18). The formation of these noncentrosymmetric framework materials is dictated by the structure, symmetry, and hydrogen-bonding properties of the [2-methylpiperazineH(2)](2+) cations.

Symmetry preservation in a new noncentrosymmetric lattice comprised of acentric POM clusters residing in bowls of Cs(+)-based half SOD ß-cage.

In light of ever growing interests in noncentrosymmetric materials, a fascinating reticular chemistry is illustrated via the structure of a new family of solids where the acentric symmetry of the well-known [V(4+)(14)As(3+)(8)O(42)Cl](5-) POM cluster is manifested through the network construction of counter cations featuring slabs of Cs(+)-based half SOD ß-cages.