Temperature-dependence and excitation-intensity-dependence of photoluminescence spectra for both disordered and ordered Ga 0.52 In 0.48 P are measured. The disordered sample is characterized by its single peak photolu...Temperature-dependence and excitation-intensity-dependence of photoluminescence spectra for both disordered and ordered Ga 0.52 In 0.48 P are measured. The disordered sample is characterized by its single peak photoluminescence spectrum which is excitation-intensity independent and has different activation energy at different temperature region. The ordered sample shows double peaks, the intensity of the high-energy peak has an anomalous increase firstly and quenches afterwards. The relative phenomena are reasonably explained in terms of lattice ordering and orientation superlattice model.展开更多
Abstract: Organic multiple quantum well(OMQ) structures consisting of alternating layers of tris(8 - quinolinolato)aluminum( ff) (Alq3) and 2 - (4 - biphenylyl) -5 - (4 - ter - butylphenyl) -(1,3,3- oxadiazole) (PBD) ...Abstract: Organic multiple quantum well(OMQ) structures consisting of alternating layers of tris(8 - quinolinolato)aluminum( ff) (Alq3) and 2 - (4 - biphenylyl) -5 - (4 - ter - butylphenyl) -(1,3,3- oxadiazole) (PBD) have been fabricated by organic molecular beam deposition (OMBD). The individual layer thickness in the multilayer samples was varied from 6 nm to 20 nm. The multiple quantum well structures were determined by low angle X - ray diffraction, optical absorption and photolumi-nescence(PL). The PL spectra narrow and the emission energy has been observed to shift to higher energy compared with that in the monolayer structure, suggesting a quantum size effect.展开更多
Pure-Ge/Si short period superlattice (SPS) grown by gas source MBE (GSMBE) is studied by photoluminescence spectroscopy and Raman scattering spectroscopy. An abnormal band in photoluminescence is found in an intermedi...Pure-Ge/Si short period superlattice (SPS) grown by gas source MBE (GSMBE) is studied by photoluminescence spectroscopy and Raman scattering spectroscopy. An abnormal band in photoluminescence is found in an intermediate range of Lsi between 1.9 nm-2.9 nm for samples with LGe fixed at 1.5 ml. In contrast to a pure-Ge/Si quantum well, the energy of the band shows red-shift as Lsi increases. Raman scattering shows that Si-Si vibration related Raman shift reaches a minimum for samples with strongest PL intensity of the abnormal band. It is therefore concluded that the abnormal band is related with strain relaxation process.展开更多
The photo absorbing, photo transmitting and photoluminescence performances of WiO2 photocatalysts compounded with V2O5 or WO3 were investigated by UV-Vis spectra, transmitting spectra, and PL spectra, respectively. Th...The photo absorbing, photo transmitting and photoluminescence performances of WiO2 photocatalysts compounded with V2O5 or WO3 were investigated by UV-Vis spectra, transmitting spectra, and PL spectra, respectively. The energy band structures of TiO2 photocatalysts were analyzed. The photocatalytic activities of the TiO2 photocatalysts were investigated by splitting of water for 02 evolution. The results indicate that the band gaps of WO3 and V205 are about 2.8 and 2.14 eV, respectively, and the band gap of rutile TiO2 is about 3.08 eV. Speeds of water splitting for 2%WO3-TiO2 and 8%V2O5-TiO2 photocatalysts are 420 and 110 μmol/（L.h）, respectively, under UV light irradiation. V2O5 and WO3 compounded with suitable concentration can improve the photocatalytic activity of TiO2 with Fe3＋ as electron acceptor.展开更多
Quantum confinement effect（QCE）, an essential physical phenomenon of semiconductors when the size becomes comparable to the exciton Bohr radius, typically results in quite different physical properties of low-dimens...Quantum confinement effect（QCE）, an essential physical phenomenon of semiconductors when the size becomes comparable to the exciton Bohr radius, typically results in quite different physical properties of low-dimensional materials from their bulk counterparts and can be exploited to enhance the device performance in various optoelectronic applications. Here, taking Cs Pb Br3 as an example, we reported QCE in all-inorganic halide perovskite in two-dimensional（2D） nanoplates. Blue shifts in optical absorption and photoluminescence spectra were found to be stronger in thinner nanoplates than that in thicker nanoplates, whose thickness lowered below -7 nm. The exciton binding energy results showed similar trend as that obtained for the optical absorption and photoluminescence. Meanwile, the function of integrated intensity and full width at half maximum and temperature also showed similar results, further supporting our conclusions. The results displayed the QCE in all-inorganic halide perovskite nanoplates and helped to design the all-inorganic halide perovskites with desired optical properties.展开更多
文摘Temperature-dependence and excitation-intensity-dependence of photoluminescence spectra for both disordered and ordered Ga 0.52 In 0.48 P are measured. The disordered sample is characterized by its single peak photoluminescence spectrum which is excitation-intensity independent and has different activation energy at different temperature region. The ordered sample shows double peaks, the intensity of the high-energy peak has an anomalous increase firstly and quenches afterwards. The relative phenomena are reasonably explained in terms of lattice ordering and orientation superlattice model.
文摘Abstract: Organic multiple quantum well(OMQ) structures consisting of alternating layers of tris(8 - quinolinolato)aluminum( ff) (Alq3) and 2 - (4 - biphenylyl) -5 - (4 - ter - butylphenyl) -(1,3,3- oxadiazole) (PBD) have been fabricated by organic molecular beam deposition (OMBD). The individual layer thickness in the multilayer samples was varied from 6 nm to 20 nm. The multiple quantum well structures were determined by low angle X - ray diffraction, optical absorption and photolumi-nescence(PL). The PL spectra narrow and the emission energy has been observed to shift to higher energy compared with that in the monolayer structure, suggesting a quantum size effect.
文摘Pure-Ge/Si short period superlattice (SPS) grown by gas source MBE (GSMBE) is studied by photoluminescence spectroscopy and Raman scattering spectroscopy. An abnormal band in photoluminescence is found in an intermediate range of Lsi between 1.9 nm-2.9 nm for samples with LGe fixed at 1.5 ml. In contrast to a pure-Ge/Si quantum well, the energy of the band shows red-shift as Lsi increases. Raman scattering shows that Si-Si vibration related Raman shift reaches a minimum for samples with strongest PL intensity of the abnormal band. It is therefore concluded that the abnormal band is related with strain relaxation process.
基金Project(11JJ5010) supported by the Natural Science Foundation of Hunan Province, ChinaProject(2011RS4069) supported by the Planned Science and Technology Program of Hunan Province, ChinaProject supported by the Postdoctoral Science Foundation of Central South University,China
文摘The photo absorbing, photo transmitting and photoluminescence performances of WiO2 photocatalysts compounded with V2O5 or WO3 were investigated by UV-Vis spectra, transmitting spectra, and PL spectra, respectively. The energy band structures of TiO2 photocatalysts were analyzed. The photocatalytic activities of the TiO2 photocatalysts were investigated by splitting of water for 02 evolution. The results indicate that the band gaps of WO3 and V205 are about 2.8 and 2.14 eV, respectively, and the band gap of rutile TiO2 is about 3.08 eV. Speeds of water splitting for 2%WO3-TiO2 and 8%V2O5-TiO2 photocatalysts are 420 and 110 μmol/（L.h）, respectively, under UV light irradiation. V2O5 and WO3 compounded with suitable concentration can improve the photocatalytic activity of TiO2 with Fe3＋ as electron acceptor.
基金supported by the National Basic Research Program of China (2014CB931702)the National Key Research and Development Program of China (2016YFB0401701)+5 种基金the National Natural Science Foundation of China (NSFC 51572128 and 21403109)NSFC-RGC (5151101197)the Natural Science Foundation of Jiangsu Province (BK20160827)China Postdoctoral Science Foundation (2016M590455)the Fundamental Research Funds for the Central Universities (30915012205 and 30916015106)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Quantum confinement effect（QCE）, an essential physical phenomenon of semiconductors when the size becomes comparable to the exciton Bohr radius, typically results in quite different physical properties of low-dimensional materials from their bulk counterparts and can be exploited to enhance the device performance in various optoelectronic applications. Here, taking Cs Pb Br3 as an example, we reported QCE in all-inorganic halide perovskite in two-dimensional（2D） nanoplates. Blue shifts in optical absorption and photoluminescence spectra were found to be stronger in thinner nanoplates than that in thicker nanoplates, whose thickness lowered below -7 nm. The exciton binding energy results showed similar trend as that obtained for the optical absorption and photoluminescence. Meanwile, the function of integrated intensity and full width at half maximum and temperature also showed similar results, further supporting our conclusions. The results displayed the QCE in all-inorganic halide perovskite nanoplates and helped to design the all-inorganic halide perovskites with desired optical properties.
