Weiling Luan

Facile synthesis of flake-like FeSe2 particles in open-air conditions

FeSe2 particles were facilely synthesized through a simple solvothermal reduction reaction in air. By using iron nitrate and selenide as raw materials, and oleylamine as solvent, 96% yield of the FeSe2 particles with flake-like structures was obtained. Different morphologies of the FeSe2 particles, such as globular, flocculent, and flake structures, were achieved by changing the reaction temperatures. Meanwhile, the probable growth mechanism and fabrication process of the products were proposed. The Raman spectra of the FeSe2 samples showed the characteristic peaks of Se–Se active modes. The optical properties demonstrated that the products had a broad optical absorption in NIR, which was related to the corresponding microstructure.

A simple route for synthesis of PbSe nanocrystals: shape control by ligand and reaction time

The shape controlled synthesis of high quality colloidal lead selenide (PbSe) nanocrystals (NCs) was achieved through a simple solvothermal process. By using oleic acid (OA) as a ligand and activating agent for the Pb precursor, the evolution of the NCs from nanospheres to nanoflowers and finally to nanocubes was achieved by increasing the reaction time. Further, the shape variation from nanospheres to polyhedrons was readily realized through the increase of OA concentration in the stock solution. More interestingly, the change of the anion ligand was proven to be a facile method to control the structure and size of the nanoflowers. The X-ray diffraction and TEM analysis demonstrated the cubic rock salt structure of the synthesized PbSe NCs. Accompanied by comprehensive analytics, the discussion on the possible mechanisms for the shape evolution was provided.

Optical response of a quantum dot–epoxy resin composite: effect of tensile strain

The structural applications of quantum dots (QDs) can be artificially realized through the preparation of QDs-based structural materials, which have unique characteristics of photoluminescence (PL) in response to mechanical deformation, via the dispersion of quantum dots in various materials, including polymers and plastics. A QDs-based composite consisting of CdSe@ZnS core–shell QDs and a bisphenol-A type epoxy resin has been prepared by mixing a solution of CdSe@ZnS core–shell QDs in chloroform with bisphenol-A type epoxy resin and modified amine at room temperature. The tensile deformation of the tensile specimens made from the QDs-based composite causes a significant change in the PL intensity for large engineering strains, and there is no observable strain-induced shift of the wavelength corresponding to the maximum PL intensity. Two major modes are observed for the temporal variation of the PL intensity of the QDs-based composite coated on AA 7009 tensile specimens under cyclic loading and unloading of small strains. One exhibits in-phase characteristics with strain, and the other exhibits antiphase characteristics with strain. The variation of the PL intensity of the QDs-based composite with tensile strain suggests that there exists strain-dependent photoluminescence, which determines the PL characteristics of the CdSe@ZnS core–shell QDs in the bisphenol-A type epoxy under the irradiation of ultraviolet light. The experimental results demonstrate the potential of developing sensitive opto-mechanical devices from QDs-based composites.

A high quality and quantity hybrid perovskite quantum dots (CsPbX3, X= Cl, Br and I) powders synthesis via ionic displacement

Recently, all-inorganic perovskites CsPbX3 (X= Cl, Br and I) quantum dots (QDs) have drawn great attentions because of their PL spectra tunable over the whole visible spectral region (400-700 nm) and adjustable bandgap, which revealed a promising potential on the field of photoelectronic devices, such as solar cells, LEDs and sensors. In this paper, CsPbX3 QDs and hybrid QDs, CsPbClxBr3-x and CsPbBrxI3-x were synthesized via one-step and two-step methods comparably. The optical bandgaps of CsPbCl3, CsPbBr3, and CsPbI3, were calculated as 3.08, 2.36, and 1.73eV, respectively, based on the Taucs equation and UV absorption spectra. Ionic displacement and phase transformation occurred during the mixing process were found based on the monitoring of PL spectra and HRTEM characterization. The long-term stability, dried, high quality and two-dimensional hybrid CsPbBrxI3-x QDs powders could be achieved via the two-step method. Polar solution inductions were used to wash and purify the CsPbX3 QDs, which help obtain of various compositions and well crystallize all-inorganic perovskites QDs powders.

Effects of CdSe nanodot in organic solar cells with blends of poly(3-hexylthiophene) and soluble fullerene

We fabricated the inverted organic solar cells with ternary system of CdSe nanodots, poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM). The solar cell by incorporation of 10 wt% CdSe nanodots showed increased power conversion efficiency (PCE) compared with that of binary system with P3HT and PCBM. The addition of CdSe nanodots had positive effect on the solar cell performance. A promising PCE of 3.05% was achieved, which is comparable with the best reported efficiency of adding shape tailored CdSe.