Single-junction,lattice-mismatched In0.69Ga0.31As thermophotovoltaic（TPV） devices each with a bandgap of 0.6 eV are grown on InP substrate by metal-organic chemical vapour deposition（MOCVD）.Compositionally undulat...Single-junction,lattice-mismatched In0.69Ga0.31As thermophotovoltaic（TPV） devices each with a bandgap of 0.6 eV are grown on InP substrate by metal-organic chemical vapour deposition（MOCVD）.Compositionally undulating stepgraded InAsyP1-y buffer layers with a lattice mismatch of ～1.2% are used to mitigate the effect of lattice mismatch between the device layers and the InP substrate.With an optimized buffer thickness,the In0.69Ga0.31As active layers grown on the buffer display a high crystal quality with no measurable tetragonal distortion.High-performance single-junction devices are demonstrated,with an open-circuit voltage of 0.215 V and a photovoltaic conversion efficiency of 6.9% at a short-circuit current density of 47.6 mA/cm2,which are measured under the standard solar simulator of air mass 1.5-global（AM 1.5 G）.展开更多
The phase and the structure of polycrystal material, which was prepared by calcining the co precipitated fluoride powder of Sr and La with a ratio of 0.69∶0.31 mixed with SrS powder, were investigated by X ray diffra...The phase and the structure of polycrystal material, which was prepared by calcining the co precipitated fluoride powder of Sr and La with a ratio of 0.69∶0.31 mixed with SrS powder, were investigated by X ray diffraction and electron probe scanning. In the materials, three phases were found, they are Sr 0.69 La 0.31 F 2.31 solid solution phase with a pure SrF 2 cubic structure whose lattice constant is 5.843 ?, SrS single phase with a NaCl cubic structure, and an unknown phase that is produced by the interaction of SrS and co precipitated powder. It was also found that SrS has no influence on the structure of Sr 0.69 La 0.31 F 2.31 solid solution.展开更多
A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out i...A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out in the presence of polyeth- ylene glycol, PEG 6000 as a surfactant/surface modifier, providing small size and homogeneity of the products. The synthesized compounds were composed of small nanoparticles with an average size of 15 nm. All obtained Eu3＋ doped compounds exhibited an intensive red luminescence. In the case of gadolinium based compounds, the energy transfer phenomena could be observed from Gd3＋ ions to Eu3＋ ions. In order to study the structure and morphology of the synthesized fluorides, powder X-ray diffraction （XRD） and transmission electron microscopy （TEM） measurements were performed. Also FT-IR spectra of the products were re- corded, revealing the presence of PEG molecules on the nanoparticles suN＇ace. A spectrofluorometry technique was applied to examine optical properties of the synthesized nanoparticles. Excitation and emission spectra as well as luminescence decay curves were measured and analysed. The performed analysis revealed a red luminescence, typical for the Eu3＋ ion situated in the inorganic, highly symmetric matrix. Concentration quenching phenomena and lifetimes shortening, together with an increasing of the Eu3＋ doping level, were observed and discussed. Judd-Ofelt analysis was also performed for all doped samples, in order to support the registered spectroscopic data and examine in details structural and optoelectronic properties of the synthesized nanomaterials.展开更多
基金Project supported by the National Basic Research Program of China (Grant No. 61176128)the Knowledge Innovation Project of the Chinese Academy of SciencesSuzhou Municipal Solar Cell Research Project,China (Grant No. SYG201145)
文摘Single-junction,lattice-mismatched In0.69Ga0.31As thermophotovoltaic（TPV） devices each with a bandgap of 0.6 eV are grown on InP substrate by metal-organic chemical vapour deposition（MOCVD）.Compositionally undulating stepgraded InAsyP1-y buffer layers with a lattice mismatch of ～1.2% are used to mitigate the effect of lattice mismatch between the device layers and the InP substrate.With an optimized buffer thickness,the In0.69Ga0.31As active layers grown on the buffer display a high crystal quality with no measurable tetragonal distortion.High-performance single-junction devices are demonstrated,with an open-circuit voltage of 0.215 V and a photovoltaic conversion efficiency of 6.9% at a short-circuit current density of 47.6 mA/cm2,which are measured under the standard solar simulator of air mass 1.5-global（AM 1.5 G）.
文摘The phase and the structure of polycrystal material, which was prepared by calcining the co precipitated fluoride powder of Sr and La with a ratio of 0.69∶0.31 mixed with SrS powder, were investigated by X ray diffraction and electron probe scanning. In the materials, three phases were found, they are Sr 0.69 La 0.31 F 2.31 solid solution phase with a pure SrF 2 cubic structure whose lattice constant is 5.843 ?, SrS single phase with a NaCl cubic structure, and an unknown phase that is produced by the interaction of SrS and co precipitated powder. It was also found that SrS has no influence on the structure of Sr 0.69 La 0.31 F 2.31 solid solution.
基金Project supported by Polish Ministry of Science and Higher Education(Diamond Grant"Nr DI2011 011441)
文摘A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out in the presence of polyeth- ylene glycol, PEG 6000 as a surfactant/surface modifier, providing small size and homogeneity of the products. The synthesized compounds were composed of small nanoparticles with an average size of 15 nm. All obtained Eu3＋ doped compounds exhibited an intensive red luminescence. In the case of gadolinium based compounds, the energy transfer phenomena could be observed from Gd3＋ ions to Eu3＋ ions. In order to study the structure and morphology of the synthesized fluorides, powder X-ray diffraction （XRD） and transmission electron microscopy （TEM） measurements were performed. Also FT-IR spectra of the products were re- corded, revealing the presence of PEG molecules on the nanoparticles suN＇ace. A spectrofluorometry technique was applied to examine optical properties of the synthesized nanoparticles. Excitation and emission spectra as well as luminescence decay curves were measured and analysed. The performed analysis revealed a red luminescence, typical for the Eu3＋ ion situated in the inorganic, highly symmetric matrix. Concentration quenching phenomena and lifetimes shortening, together with an increasing of the Eu3＋ doping level, were observed and discussed. Judd-Ofelt analysis was also performed for all doped samples, in order to support the registered spectroscopic data and examine in details structural and optoelectronic properties of the synthesized nanomaterials.
