The local structure of an alternative Pb（Zn1/3Nb2/3）O3-based perovskite ceramic is investigated. The 0.07BaTiO33-0.93Pb（Zn1/3Nb2/3）O3 ceramic is synthesized using a combination of Zn3Nb2O8 B-site precursor and BaT...The local structure of an alternative Pb（Zn1/3Nb2/3）O3-based perovskite ceramic is investigated. The 0.07BaTiO33-0.93Pb（Zn1/3Nb2/3）O3 ceramic is synthesized using a combination of Zn3Nb2O8 B-site precursor and BaTiO33 perovskite phase stabilizer. Then, x-ray absorption spectroscopy and density functional theory are employed to calculate the local structure configuration and formation energy of the prepared samples. Ba2＋ is found to replace Pb2＋ in AA-site with Zn2＋ occupying BB-site in Pb（Zn1/3Nb2/3）O3, while in the neighboring structure, Ti4＋4＋ replaces Nb5＋5＋ in BB-site with Pb2＋2＋ occupying AA-site. With the substitution of BaTiO33 in Pb（Zn1/3Nb2/3）O3, the bond length between Zn2＋ and Pb2＋ is longer than that of the typical perovskite phase of Pb（Zn1/3Nb2/3）O3. This indicates the key role of BaTiO33 in decreasing the steric hindrance of Pb2＋ lone pair, and the mutual interactions between Pb2＋ lone pair and Zn2＋ and the formation energy is seen to decrease. This finding of the formation energy and local structure configuration relationship can further extend a fundamental understanding of the role of BaTiO33 in stabilizing the perovskite phase in PbZn13Nb23O3-based materials, which in turn will lead to an improved preparation technique for desired electrical properties.展开更多
Hybrid organic-inorganic solar cell devices were fabricated utilizing macroporous n-type GaP and poly（3,4-ethylenedioxythiophene）：poly（4-styrene sulfonate） （PEDOT：PSS）. The high-aspect ratio structures of the ...Hybrid organic-inorganic solar cell devices were fabricated utilizing macroporous n-type GaP and poly（3,4-ethylenedioxythiophene）：poly（4-styrene sulfonate） （PEDOT：PSS）. The high-aspect ratio structures of the macroporous GaP resulted in higher photocurrent and external quantum yield as a function of wavelength. Photocurrent-voltage measurements as a function of light intensity revealed information on the dependence of short-circuit current （Jsc） and open-circuit voltage （Voc） on light intensity. Under 1.0 Sun illumination, hybrid macroporous GaPJPEDOT：PSS devices showed Jsc of 2.34 mA cm 2, Voc of 0.95 V, fill factor of 0.54, and overall efficiency of 1.21%. The extent of the influence of dopant density of GaP on hybrid device performance was probed with current density-voltage measurements. The addition of a gold nanoparticle coating on macroporous GaP prior to PEDOT：PSS coating showed increased device performance, with overall efficiency of 1.81%. Gold-modified planar GaPJPEDOT：PSS showed decreased Jsc and Voc values and lower external quantum yield over all wavelengths,展开更多
基金Supported by the Thailand Research Fund under Grant No TRG5880097
文摘The local structure of an alternative Pb（Zn1/3Nb2/3）O3-based perovskite ceramic is investigated. The 0.07BaTiO33-0.93Pb（Zn1/3Nb2/3）O3 ceramic is synthesized using a combination of Zn3Nb2O8 B-site precursor and BaTiO33 perovskite phase stabilizer. Then, x-ray absorption spectroscopy and density functional theory are employed to calculate the local structure configuration and formation energy of the prepared samples. Ba2＋ is found to replace Pb2＋ in AA-site with Zn2＋ occupying BB-site in Pb（Zn1/3Nb2/3）O3, while in the neighboring structure, Ti4＋4＋ replaces Nb5＋5＋ in BB-site with Pb2＋2＋ occupying AA-site. With the substitution of BaTiO33 in Pb（Zn1/3Nb2/3）O3, the bond length between Zn2＋ and Pb2＋ is longer than that of the typical perovskite phase of Pb（Zn1/3Nb2/3）O3. This indicates the key role of BaTiO33 in decreasing the steric hindrance of Pb2＋ lone pair, and the mutual interactions between Pb2＋ lone pair and Zn2＋ and the formation energy is seen to decrease. This finding of the formation energy and local structure configuration relationship can further extend a fundamental understanding of the role of BaTiO33 in stabilizing the perovskite phase in PbZn13Nb23O3-based materials, which in turn will lead to an improved preparation technique for desired electrical properties.
基金supported by the National Science Foundation under Grant # DMR-1054303
文摘Hybrid organic-inorganic solar cell devices were fabricated utilizing macroporous n-type GaP and poly（3,4-ethylenedioxythiophene）：poly（4-styrene sulfonate） （PEDOT：PSS）. The high-aspect ratio structures of the macroporous GaP resulted in higher photocurrent and external quantum yield as a function of wavelength. Photocurrent-voltage measurements as a function of light intensity revealed information on the dependence of short-circuit current （Jsc） and open-circuit voltage （Voc） on light intensity. Under 1.0 Sun illumination, hybrid macroporous GaPJPEDOT：PSS devices showed Jsc of 2.34 mA cm 2, Voc of 0.95 V, fill factor of 0.54, and overall efficiency of 1.21%. The extent of the influence of dopant density of GaP on hybrid device performance was probed with current density-voltage measurements. The addition of a gold nanoparticle coating on macroporous GaP prior to PEDOT：PSS coating showed increased device performance, with overall efficiency of 1.81%. Gold-modified planar GaPJPEDOT：PSS showed decreased Jsc and Voc values and lower external quantum yield over all wavelengths,
