R.K. Parida; B.N Parida; R. K. Bhuyan; S. K. Parida
Abstract
The La modified bismuth ferrite perovskite Bi0.6La0.4FeO3 (BLF) is prepared by cost-effective high solid-solution casting technique. Formation of composite is checked through X-ray diffraction and also notable that there is phase transition from rhombohedral (R3c) to orthorhombic (Pbnm). The average ...
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The La modified bismuth ferrite perovskite Bi0.6La0.4FeO3 (BLF) is prepared by cost-effective high solid-solution casting technique. Formation of composite is checked through X-ray diffraction and also notable that there is phase transition from rhombohedral (R3c) to orthorhombic (Pbnm). The average crystalline size (DSC) and mechanical lattice strain are 63.8 nm and 0.147% respectively as calculated by Williamson-Hall method. The frequency bands corresponding to Bi-O, LaO, and FeO stretching vibration confirm that La+3 ions completely incorporate the Bi+3 ions in the A-site of the single perovskite. The SEM micrograph suggests that the sample has distinct grains and well-defined grain boundaries and the average grain size (DSEM) is about 13.9 μm. The rate of agglomeration that acquire in the sample (DSEM/ DSC = 219) confirms the excellent connectivity of grains which stands possible reason for the high dielectric and conductivity. The impedance analysis provided the fact that bulk resistance (Rb) decreases from 6.662 x 105 Ω at 25 0 C to 1.000 x 10-2 Ω at 350 0 C; suggesting NTCR behaviour of the material. The activation energy increases from 201 meV to 677meV with temperature supports a thermally activated conduction mechanism. The thermally activated relaxation process is controlled by the immobile charge carriers at lower temperature range while controlled by defects at higher temperatures which suggests the presence of hopping mechanism. The gap between the peak of 𝐙′′and 𝐌′′ is becoming wide with temperature suggests a non-Debye type character. The semicircular arcs in both Nyquist plots and Cole-Cole plots are confirming the semiconductor nature.
Abhinav Bhatnagar; Vijay Janyani
Abstract
Over the past few years thin film planar heterojunctions solar cells have made much progress as a low cost with high power conversion efficiency photovoltaic devices. Among the materials used in fabricating such solar cells organometal trihalide perovskite (MAPbI3) has proven to be a promising absorber ...
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Over the past few years thin film planar heterojunctions solar cells have made much progress as a low cost with high power conversion efficiency photovoltaic devices. Among the materials used in fabricating such solar cells organometal trihalide perovskite (MAPbI3) has proven to be a promising absorber material due to cheaper organic-inorganic perovskite compounds, abundantly available in nature, ease of fabrication and compatible with low temperature large scale processing. In addition to the efficient absorption in ultra-violet range the material possess intriguing optoelectronic properties such as high crystallinity, high carrier mobility and large carrier diffusion lengths. Currently, the highest power conversion efficiency achieved by such perovskite solar cells is only 23.9% as reported in 2017. In this work we demonstrate a thin film organometal trihalide perovskite solar cell with hybrid interfaces between different materials which are selected after extensive study to achieve reduced recombination and high performance. Further, the absorption of the incident solar spectrum is enhanced by incorporating a 1D photonic crystal at the bottom of the cell facilitating the photon recycling process. The proposed solar cell parameters are numerically computed using rigorous coupled wave algorithm through SYNOPSYS RSOFT CAD tool. The thickness of each layer of the structure is optimized using MOST scanning and optimization module of RSOFT CAD tool to achieve highest power conversion efficiency at minimum device thickness (~2 µm). The power conversion efficiency thus obtained is 25.2% with a fill factor of 86.3% at AM 1.5, which is very promising. This demonstrates the remarkable potential of the proposed design to achieve efficiencies over 20% and compete with the existing crystalline silicon photovoltaic market.
Yidi Wang; Pui Fai NG; Bin Fei
Abstract
Hybrid organic–inorganic perovskite materials have attracted a lot of attention with their facile synthesis process and high efficiency of light absorption. However, poor stability is always a big barrier to commercial development. In this study, a new kind of organic perovskites MA0.6(AA)0.4PbBr3 ...
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Hybrid organic–inorganic perovskite materials have attracted a lot of attention with their facile synthesis process and high efficiency of light absorption. However, poor stability is always a big barrier to commercial development. In this study, a new kind of organic perovskites MA0.6(AA)0.4PbBr3 (AM-PE), which harnesses aniline as a replacement of conventionally used methylamine, was synthesized to increase the stability of MAPbBr3 (M-PE). The decomposition process of MAPbBr3 in acetone was investigated. Smaller PbBr2 particles were formed in the decomposition process, causing the change of photoluminescence emission wavelength from 540 nm to 610 nm. The photocatalysis and photoluminescence properties of M-PE and AM-PE were also compared. As a result, the introduction of aniline reduced the decomposition rate of AM-PE significantly and showed twice the catalysis efficiency of M-PE in the degradation of organic dye - malachite green.
Yulong Ma; Kaimo Deng; Bangkai Gu; Hao Lu; Yayun Zhu; Liang Li
Abstract
The electron transport material has the great effect on the performance of hybrid perovskite solar cells. TiO2 is widely chosen as the electron transport layer due to its facile synthesis and excellent charge extraction capability. Here, for the first time, we utilize the hydrogen treated TiO2 as the ...
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The electron transport material has the great effect on the performance of hybrid perovskite solar cells. TiO2 is widely chosen as the electron transport layer due to its facile synthesis and excellent charge extraction capability. Here, for the first time, we utilize the hydrogen treated TiO2 as the electron transport layer for improving the performance of perovskite solar cells. The hydrogen treatment increases the Fermi level and conductivity of TiO2, and the device based on hydrogen treated TiO2 exhibits a power conversion efficiency of 13.15% compared with 9.45% for the reference device with untreated TiO2. The results highlight the importance of optimizing the electron transport material and provide a new route to fabricate highly efficient planar perovskite solar cells.
Hamzah Fansuri; Muhammad I. Syafi
Abstract
The aims of this research are to study the sintering technique during the production of BaxSr1-xCo0.8Fe0.2O3-δ (BSCF) membranes and to obtain information about the correlation between Ba 2+ substituent with membrane’s density, hardness and thermal expansion coefficient. BSCF with x = 0.5, ...
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The aims of this research are to study the sintering technique during the production of BaxSr1-xCo0.8Fe0.2O3-δ (BSCF) membranes and to obtain information about the correlation between Ba 2+ substituent with membrane’s density, hardness and thermal expansion coefficient. BSCF with x = 0.5, 0.6 and 0.7 (BSCF 5582, 6482 and 7382) were synthesized by the solid state method. X-ray diffraction analysis revealed that the three oxides possessed a cubic structure with high purity and crystallinity. BSCF membranes were made by dry pressing method from their respective powders which passed through 400 mesh sieves at 1050 o C and 1150 o C. Membranes with high density were obtained from phased sintering technique at 1150 °C. SEM analysis results showed that the surface of the membranes is dense, albeit pores can still be found in the cross section of the membranes. The density of the membranes decreased as the amount of Ba 2+ substituent increases indicated by the increase in pore size. A similar pattern was also found in the membrane hardness which decreased as the amount of Ba 2+ content increased. Thermal expansion coefficient of BSCF 5582 was 18.28 ppm which was the highest one followed by BSCF 6482 and BSCF 7382.
Rajan Kumar Singh; Neha Jain; Jai Singh; Ranveer Kumar
Abstract
This is the first time that a highly purified white organic electrolyte salts (OES), Methylammonium iodide, CH3NH3I (MAI) and Methylammonium chloride, CH3NH3Cl (MACl) have been successfully synthesized by a new technique, high vacuum oven evaporation method (HVOE), which is inexpensive and less time ...
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This is the first time that a highly purified white organic electrolyte salts (OES), Methylammonium iodide, CH3NH3I (MAI) and Methylammonium chloride, CH3NH3Cl (MACl) have been successfully synthesized by a new technique, high vacuum oven evaporation method (HVOE), which is inexpensive and less time consumable. Thermal stability of organic salt, pure and mixed perovskite light harvester materials (PLHM) are studied by STA (DTG/DTA). CH3NH3I and CH3NH3Cl undergo ~100% weight loss in one step, at temperature 310 o C and 350 o C, respectively. Additionally, CH3NH3PbI3 is more thermally stable than mixed halide perovskite CH3NH3PbI3-xCl. Stability behavior of organic salts and CH3NH3PbI3-xClx is analyzed by Raman study which indicates that organic salts are stable in ambient conditions and CH3NH3PbI3-xClx is not stable in ambient condition. Different stretching and banding modes of organic and inorganic materials are indentified by study of Raman spectra.
Soumya Mukherjee; Manoj Kumar Mitra
Abstract
Multiferroic materials are new class of multi-functional materials which possess both ferro-electric and magnetic properties. This type of material has wide range of applications like semi-conducting to sensors applications. Nanocomposite of equimolar perovskite-spinel is synthesized by chemical ...
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Multiferroic materials are new class of multi-functional materials which possess both ferro-electric and magnetic properties. This type of material has wide range of applications like semi-conducting to sensors applications. Nanocomposite of equimolar perovskite-spinel is synthesized by chemical route by blending of Nickel ferrite as second phase on Bismuth ferrite after heat treatment at 500 °C for 2, 3 and 4 hours soaking period. From the diffractogram data of XRD, the phase, and planes of orientation are analyzed of the synthesized materials. The crystallite size is calculated by Scherrer’s formula. FESEM studies reveal the morphological features having interconnected agglomerates with spherical, irregular polygonal or some elongated shape of the synthesized nanocomposite. FTIR result shows the molecular signature of the nanocrystalline material to verify the M-O coordination. Interplanar spacings and SAED pattern are revealed from HRTEM images which are very close to the experimental findings from XRD phase analysis. UV-VIS analysis is performed in the transmission mode of spectra within the scan range of 200-1100 nm. From the spectra, using Tauc relation band gap is calculated. Band gap are found of the order of 2.847 eV, 2.78 eV, 2.69 eV respectively for 2, 3 and 4 hours soaking period close to semiconducting material. With the increase of soaking time band gap is found to decrease following Arrhenius activation of electronic mobility overwhelming the energy barrier at respective lattice sites. M-H analysis of Nanocomposite at 500 °C for 2 hrs is closer towards ferromagnetic with incomplete loop but for sample at 500 °C for 4hrs it is closer towards superparamagnetic one. The property of this material reflects it has many interesting characteristics suitable for opto-electronic, photo-magnetic devices and other electronic applications.
P. Kumari; R. Rai; A. L. Kholkin; A. Tiwari
Abstract
The ferroelectric Ca doped (Ba0.9575La0.04X0.0025) (Ti0.815Mn0.0025Nb0.0025Zr0.18)0.99O3 was prepared by a high-temperature solid state reaction technique. For the understanding of the electrical and dielectric property, the relation between the crystal structures, electrical transition and ferroelectric ...
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The ferroelectric Ca doped (Ba0.9575La0.04X0.0025) (Ti0.815Mn0.0025Nb0.0025Zr0.18)0.99O3 was prepared by a high-temperature solid state reaction technique. For the understanding of the electrical and dielectric property, the relation between the crystal structures, electrical transition and ferroelectric transitions with increasing temperature ( –160 to 35°C) have been analyzed. X- ray diffraction analysis of the powders suggests the formation of a single-phase material with monoclinic structure. Capacitance and tanδ of the specimens were measured in the temperature range from -160 to 35°Cat frequencies 1 kHz – 1 MHz. Detailed studies of dielectric and electrical properties indicate that the Curie temperature shifted to higher temperature with the increase in frequency. Moreover, the dielectric maxima dropped down rapidly initially and the dielectric peaks became extremely broad. The AC conductivity increases with increase in frequency. The low value of activation energy obtained for the ceramic samples could be attributed to the influence of electronic contribution to the conductivity.
S. Bhagat; K. Amar Nath; K.P. Chandra; R.K. Singh; A.R. Kulkarni; K. Prasad
Abstract
Lead-free pseudo-binary compounds (1-x)Ba(Fe1/2Nb1/2)O3–xBaTiO3; (0 ≤ x ≤ 1) have been synthesized at 1200°C using conventional ceramic technique and characterized by X-ray diffraction, scanning electron microscopy, dielectric and vibration sample magnetometer studies. The crystal structure ...
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Lead-free pseudo-binary compounds (1-x)Ba(Fe1/2Nb1/2)O3–xBaTiO3; (0 ≤ x ≤ 1) have been synthesized at 1200°C using conventional ceramic technique and characterized by X-ray diffraction, scanning electron microscopy, dielectric and vibration sample magnetometer studies. The crystal structure of the compounds is found to be monoclinic with the space group P2/m except for BaTiO3 for which it is tetragonal (P4/mmm). The incorporation of BaTiO3 significantly reduces the dielectric loss and improve the frequency and temperature stability of the dielectric properties of Ba(Fe1/2Nb1/2)O3. Compound 0.25Ba(Fe1/2Nb1/2)O3-0.75BaTiO3 exhibited a low value of temperature coefficient of capacitance (< ±3%) in the working temperature range (up to +85°C), room temperature dielectric constant equal to 282 and low loss tangent (~10-2) which meets the specifications for “Z5D” of Class II dielectrics of Electronic Industries Association. Hence, this composition might be a suitable candidate for capacitor applications. Besides, magnetic studies indicated the possibility of magneto-electric coupling in the system.
Seema Sharma
Abstract
Nanotechnology is one of the rapidly growing scientific disciplines due to its enormous potential in creating novel materials that have advanced applications. Electrospinning has been found to be a viable technique to produce materials in nanofiber form. Ferroelectric and/or piezoelectric materials in ...
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Nanotechnology is one of the rapidly growing scientific disciplines due to its enormous potential in creating novel materials that have advanced applications. Electrospinning has been found to be a viable technique to produce materials in nanofiber form. Ferroelectric and/or piezoelectric materials in nanofiber and/or nanowire form have been utilized for producing energy harvesting devices, high frequency transducers, implanted biosensors, vibration absorbers and composite force sensors, etc. An in-depth review of research activities on the development of ferroelectric nanofibers, fundamental understanding of the electrospinning process, and properties of nanostructured fibrous materials and their applications is provided in this article. A detailed account on the type of fibers that have been electrospun and their characteristics is also elaborated. It is hoped that the overview article will serve as a good reference tool for nanoscience researchers in ferroelectric materials.
Arun Chamola; Hemant Singh; U.C. Naithani
Abstract
(1−x)BaTiO3–xPZT(65/35) ceramics were prepared by high temperature solid state reaction technique. Structural properties of the compounds were examined using an X-ray diffraction (XRD) technique to confirm the formation of phase at room temperature. Detailed studies of dielectric properties ...
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(1−x)BaTiO3–xPZT(65/35) ceramics were prepared by high temperature solid state reaction technique. Structural properties of the compounds were examined using an X-ray diffraction (XRD) technique to confirm the formation of phase at room temperature. Detailed studies of dielectric properties of (1−x) BaTiO3–xPZT(65/35) for all compositions were in temperature range 30-200 o C reveal that the compound have transition temperature well above at the room temperature. While pure BaTiO3 ceramics exhibited a sharp phase transformation expected for normal ferroelectrics, phase transformation behavior of the (1−x)BaTiO3–xPZT(65/35) solid solutions became more diffuse with increasing PZT(65/35) contents. The diffusivity of the dielectric peaks in the compound exhibited the values between 1 and 2 where the higher value indicates the greater disorder in the systems. This was primarily evidenced by an increased broadness in the dielectric peak, with a maximum peak width occurring at x = 0.5. The temperature dependence of ac conductivity indicated that the electrical conductivity decrease above Tc on increasing the PZT(65/35) contents. This increase in the conductivity is attributed to the increase in polarizability of the materials around Tc, due to oxygen vacancies.
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