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[IEEE 2018 IEEE ISAF-FMA-AMF-AMEC-PFM Joint Conference (IFAAP) - Hiroshima (2018.5.27-2018.6.1)] 2018 IEEE ISAF-FMA-AMF-AMEC-PFM Joint Conference (IFAAP) - Data-Mining Driven Design for Novel Perovskite-type Piezoceramics
摘要： Materials Genome Initiative is envisioning the discovery, development, manufacturing and deployment of advanced materials twice as fast and at a fraction of cost. High throughput computation and experimentation will generate big data, which underscores the emergence of the fourth paradigm---data science. In contrast to machine-learning needing big-data, data-mining assisted by domain knowledge and expertise works well with a limited number of data. In this presentation, data-mining based on material genome approach were performed in field of perovskite-type oxides. New ferroelectric ceramics based on BiFeO3 for high temperature piezoelectric applications are realized with piezoresponse of 1.5~4.0 times the present commercial non-perovskite counterpart. Our essay demonstrates data-mining driven searching sure able to reduce time-to-insight and human effort on synthesization, accelerating new materials discovery and deployment.
关键词： piezoceramics,perovskite-type oxides,material genome approach,high Curie temperature,data-mining
更新于2025-09-23 15:23:52
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Perovskite CsPbBr3 single crystal detector for alpha-particle spectroscopy
摘要： Here we report the first spectroscopic alpha particle detection based on CsPbBr3 detectors with asymmetric contacts. The CsPbBr3 single crystal was grown from the melt using Bridgman method and then fabricated into detectors with different contacts. The In/CsPbBr3/Au detector presented a low dark current density (~100 nA/cm2) and temporal stable performance under high electric field (1000 V/cm). Such detector demonstrated excellent gamma ray resolving capability with a full-width at half maximum (FWHM) of ~5.9 keV for the 57Co 122 keV γ ray. The CsPbBr3 detector was capable of simultaneously resolving both the alpha particle (5.5 MeV) and γ ray (59.5 keV) peaks from 241Am radioactive isotope. The transport properties of CsPbBr3 were then determined based on the alpha particle spectra and corresponding rise time distributions. The equivalent values of electron and hole mobilities were indicated as 63 and 49 cm2/(V·s) respectively. The calculated electron and hole mobility-lifetime products were 4.5 × 10-4 and 9.5 × 10-4 cm2/V, respectively, demonstrating superior transport properties of holes over electrons in CsPbBr3. This work widens the scope of perovskite detectors to encompass charged radiation as well as high energy X/γ rays, and will significantly promote and guide further studies on perovskite materials for radiation detection applications.
关键词： CsPbBr3,Alpha particle detection,Crystal growth,Perovskite single crystal
更新于2025-09-23 15:23:52
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Unusual pressure-induced electronic structure evolution in organometal halide perovskite predicted from first-principles
摘要： Pressure has been demonstrated to be an effective parameter to alter the atomic and electronic structures of materials. By using the first-principles calculations based on density functional theory (DFT), we systematically investigated the changes in the atomic and electronic structures of the cubic MAPbI3 phase under pressures. It is found that the band gap of the compressed cubic MAPbI3 structure exhibits a remarkable redshift to 1.114/1.380 eV in DFT/HSE-SOC calculation under a mild pressure of 2.772 GPa, and subsequently shows a widening at higher pressures until ~20 GPa. As the pressure further increases, the band gap closes at ~80 GPa. Detailed structural and electronic characteristic analyses indicate that the band gap of the cubic MAPbI3 structure is determined by two competing effects: the lattice contraction decreases its band gap while the PbI6 octahedral tilting increases it. Given that, pressure can be a powerful tool to help understanding the optoelectronic properties of perovskite materials.
关键词： Density functional theory,Pressure,Organometal halide perovskite,Electronic structure
更新于2025-09-23 15:23:52
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Development of a Mixed Halide-chalcogenide Bismuth-based Perovskite MABiI <sub/>2</sub> S with Small Bandgap and Wide Absorption Range
摘要： During the last years, the lead perovskites have achieved high power conversion efficiency of 23%. However, its long-term stability and toxicity are still the crucial issues that required attention. In this study, we are the first to report on the synthesis and characterizations of a new lead-free mixed halide-chalcogenide perovskite MABiI2S (MBIS), and determined its physical and optical properties by various testing methods. The MBIS has a low bandgap of 1.52 eV, with an extended absorption onset up to over 1000 nm. Solar cells fabricated with the MBIS were inspected and device improvement were applied.
关键词： Bismuth-based perovskite,Small bandgap,Lead free perovskites
更新于2025-09-23 15:23:52
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Interaction between in-gap states and carriers at the conductive interface between perovskite oxides
摘要： The 2D electron systems of SrTiO3/NdGaO3 (STO/NGO) and amorphous-LaAlO3/SrTiO3/NdGaO3 (a-LAO/STO/NGO) heterojunctions were explored. An obvious interaction between in-gap states (IGSs) and carriers was found. The IGSs can trap a large number of carriers and enhance carrier scattering. As a result of the high density of IGSs in STO, the conductivity of STO/NGO was severely weakened. However, for a-LAO/STO/NGO heterojunctions, the high carrier density can reduce the effect of IGSs through the electrostatic screening effect. The competition between IGSs and the screening effect of carriers results in an insulator–metal transition and a strange temperature dependence of carrier density. We also explored the interaction between IGSs and carriers theoretically. A mathematical description was proposed and the calculated results showed good agreement with experimental findings.
关键词： in-gap states,perovskite oxides interface,2D electron system,electrostatic screening effect
更新于2025-09-23 15:23:52
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Growth of perovskite nanocrystals in poly-tetra fluoroethylene based microsystem: On-line and off-line measurements
摘要： Cesium lead halide perovskite nanocrystals are photoelectric nanomaterials that have potential applications in a variety of areas due to their excellent photoelectric and tunable photo luminescent properties. In this work, we investigate the synergetic effects of reaction temperature, reaction-capillary length and flow rate on the growth kinetics of perovskite nanocrystals in PTFE-based microsystem and the photoluminescence characteristics of the synthesized nanocrystals both online and offline. The on-line measurement finds that increasing the reaction temperature leads to the increase of the wavelength of the PL emission peak of the nanocrystals synthesized at different reaction temperatures decreases with the increase of the flow rate. The off-line measurement reveals that increasing the flow rate generally leads to the blueshift of the PL emission peaks and the decrease of the average size of the perovskite nanocrystals synthesized at the reaction temperature of 160 oC in the capillary length of 60 cm. Increasing temperature leads to the increase of the emission wavelength of the perovskite nanocrystals from 560 nm to 608 nm. The temperature dependence of the average size of the synthesized nanocrystals with the same synthesis conditions at different temperatures can be described by the Arrhenius relationship with an activation energy of 8.54 kJ/mol. Five different cross-sections of the synthesized perovskite nanocrystals are observed, including rhombus, hexagon, rectangle, square and quadrangle with three of them being observed for the first time.
关键词： microreaction system,morphologies,growth kinetics,reaction parameters,perovskite nanocrystal
更新于2025-09-23 15:23:52
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Uniform Cs2SnI6 Thin Films for Lead-Free and Stable Perovskite Optoelectronics via Hybrid Deposition Approaches
摘要： Herein, we synthesized uniform Cs2SnI6 films by two kinds of hybrid deposition methods by considering volume expansion involved during phase transformations. First, oblique thermal evaporation for CsI followed by SnI4 spin-coating resulted in uniform Cs2SnI6 films free of impurity phases. The rapid expansion (within 10 s of spin-coating) from CsI to Cs2SnI6 (ΔV = 106%) was accommodated by porous CsI films inhibiting crack formation. Excess SnI4 on the Cs2SnI6 after spin-coating was effectively removed by toluene washing without any damages to Cs2SnI6, and optimum deposition parameters were suggested in terms of carrier mobility. Second, annealing CsI with SnI4 vapor at 250 °C and post-annealing in the SnI4 and I2 vapor at 300 °C produced Cs2SnI6 film with complete coverage. The slow reaction (70 min for a complete conversion) provided sufficient time for complete diffusion of SnI4 into CsI without crack formation even with compact CsI. The nonradiative recombination path in Cs2SnI6 was suppressed by post-annealing in the SnI4- and I2-atmosphere, as confirmed from the enhanced photoluminescence.
关键词： Lead-free perovskite,Cs2SnI6,Electrical mobility,Oblique thermal deposition
更新于2025-09-23 15:23:52
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Enhanced visible light photocatalytic activity of BiFeO3-ZnO p-n heterojunction for CO2 reduction
摘要： The visible light photocatalytic ability of bismuth ferrite-zinc oxide composites with different molar ratios was investigated for conversion of CO2 in the gas phase. The catalysts were successfully synthesized by hydrothermal method, and characterized by XRD, EDS, FESEM, UV–vis, and PL analyses. Also, the gaseous products were identified by FTIR technique. The FESEM illustrated the well crystalline particles of ZnO and BiFeO3. The UV–vis and PL analyses revealed that by increasing BiFeO3 content, the composites showed higher optical response in visible region and higher efficiency of charge separation, respectively. Compared with the pure ZnO and BiFeO3, which had poor performances under visible light irradiation, the as-synthesized photocatalysts showed the enhanced visible light photocatalytic activity for CO2 reduction. The highest photocatalytic conversion of CO2, 21%, was achieved by the as-synthesized photocatalyst with molar ratio of 1:1 under visible light. The enhanced visible light photocatalytic activity of BiFeO3-ZnO was assigned to the synergistic effect of p-n heterojunction and visible light sensitive property of perovskite structure of BiFeO3.
关键词： Perovskite,P-n heterojunction,Gaseous phase,Photocatalyst,CO2 reduction
更新于2025-09-23 15:23:52
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Modified Becke-Johnson (mBJ) exchange potential investigation of the optoelectronic properties of XThO <sub/>3</sub> (X=Ca, Sr and Ba)
摘要： The electronic structure and optical properties of CaThO3, SrThO3, and BaThO3 in cubic perovskite structure are calculated using a density functional theory with full potential linearized augmented plane wave (FP-LAPW) method. In this study, we have used the approximations LDA, GGA and mBJ. With mBJ the best approximation to get the band gap energy. This study is conducted through five stages: (1) We have started by optimizing the lattice parameters to find the basic state of each component (2) We have calculated electronic properties such as density of state, band structure, charge density (3) and basing on the band structure we have also calculated the optical properties as dielectric function, absorption coefficient, refractive index, reflectivity and optical conductivity to discuss the different transitions and the new peaks. The mechanical (4) and thermodynamic (5) behaviour was discussed for the first time for CaThO3 and BaThO3 in the cubic phase, in terms of elastic constants, and their related parameters, such as Young modulus, shear modulus, and Poisson ratio. Our results show that XThO3 has a stable ductile trait that makes it effective for high temperature electronic applications. As result, the various new peaks in the wide UV region due to the transition of electrons confirm the application of XThO3 (X= Ca, Sr and Ba) in the field of optoelectronic devices.
关键词： Perovskite,Optical Properties,mBJ,FP-LAPW,Electronic Structure
更新于2025-09-23 15:22:29
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Semimetallicity and Negative Differential Resistance from Hybrid Halide Perovskite Nanowires
摘要： In the rapidly progressing field of organometal halide perovskites, the dimensional reduction can open up new opportunities for device applications. Herein, taking the recently synthesized trimethylsulfonium lead triiodide (CH3)3SPbI3 perovskite as a representative example, first-principles calculations are carried out and the nanostructuring and device application of halide perovskite nanowires are studied. It is found that the 1D (CH3)3SPbI3 structure is structurally stable, and the electronic structures of higher-dimensional forms are robustly determined at the 1D level. Remarkably, due to the face-sharing [PbI6] octahedral atomic structure, the organic ligand-removed 1D PbI3 frameworks are also found to be stable. Moreover, the PbI3 columns avoid the Peierls distortion and assume a semimetallic character, contradicting the conventional assumption of semiconducting metal-halogen inorganic frameworks. Adopting the bundled nanowire junctions consisting of (CH3)3SPbI3 channels with sub-5 nm dimensions sandwiched between PbI3 electrodes, high current densities and large room-temperature negative differential resistance (NDR) are finally obtained. It will be emphasized that the NDR originates from the combination of the near-Ohmic character of PbI3-(CH3)3SPbI3 contacts and a novel NDR mechanism that involves the quantum-mechanical hybridization between channel and electrode states. This work demonstrates the great potential of low-dimensional hybrid perovskites toward advanced electronic devices beyond actively pursued photonic applications.
关键词： semimetals,halide perovskite nanowires,first-principles calculations,negative differential resistance
更新于2025-09-23 15:22:29