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Propylammonium lead iodide (C3H7NH3PbI3), a promising hybrid perovskite, is successfully synthesized by a solgel technique. Structural, optical, and dielectric properties have been studied in detail. The dielectric constant, loss factor, electric modulus, and AC and DC conductivity of this hybrid perovskite exhibit strong temperature dependence over the frequency range of 10 Hz ≤ f ≤ 8 MHz. The Nyquist plot reveals the distinct contributions of grain and grain boundary to the total impedance. The dielectric constant is found to increase with temperature in the high frequency region. The modified Cole–Cole plot shows that the space charge and free charge conductivity increase with the elevation of temperature, whereas the relaxation time decreases with the rise in temperature. From the modified Kohlrausch–Williams–Watts equation, we perceived asymmetrical nature in electric modulus spectra at various temperatures, which corresponds to the non-Debye type nature of perovskite. It has also been found that, with the elevation of temperature, the imaginary part of electric modulus spectra shifts from the non-Debye type toward the Debye type nature, though failing to acquire exact Debye type response, and emerges as a semiconductor material. AC conductivity of PAPbI3 is illustrated on the basis of the correlated barrier hopping (CBH) mechanism. Activation energy estimated from both modulus spectra and DC conductivity matches well, affirming the similarity between relaxation behavior and conduction mechanism. Along with all these, PAPbI3 possesses a high dielectric constant associated with a small dielectric loss, making it a potential candidate for energy harvesting devices. [ABSTRACT FROM AUTHOR]

In this work, CsPbBr3 has been successfully synthesized via sol-gel technique. The orthorhombic phase of the material has been verified by X-ray diffraction measurement followed by Rietveld refinement analysis. Morphological study has revealed the cubic shape of particles with dimension ∼3 μm. Electrical properties are characterized by Complex impedance (Z*), dielectric permittivity (ɛ*), and ac conductivity within the frequency range 10 Hz–5 MHz for different temperatures between 313K and 673 K. The dielectric behavior of CsPbBr3 is found to be thermally activated and frequency dependent. The ascensive nature of ɛ′(ω) at lower frequency is assigned to the Maxwell-Wagner type interfacial polarization. ɛ′(ω) has been fitted using Kramers-Kronig relation by including the dielectric constant at infinite frequency. Variation of ɛ″(ω) with frequency has been explained by the hopping of charge carrier over a potential barrier between charge defects. AC conductivity has also been fitted by Jonscher's power law to find the real component of conductivity and it has been described by using the Jump relaxation model. Activation energy has been calculated by fitting the dc conductivity using Arrhenius relation and found to have a value of 0.517 eV. Grain resistance (rg), grain capacitance (cg), grain boundary resistance (rgb), and grain boundary capacitance (cgb) have been accounted by fitting Z′ vs log(f) plot with equivalent circuit and existing theoretical model. [ABSTRACT FROM AUTHOR]

The emergence of high-efficiency photovoltaic research is undergoing intense study and is technologically desirable to meet sustainable energy and environmental demand. However, every single solar cell has a theoretical power conversion efficiency limit, and, thus, without compromising the cost, the power conversion efficiency enhancement of a solar cell is highly challenging. As a convenient solution, concentrating photovoltaics can focus sunlight onto an extremely high-efficiency solar cell integrating various optics. Concentrating photovoltaics use optical devices that collect and redirect the light toward the smaller photovoltaic cell and reduce the demand for the mined elements required for the solar cell fabrication. The research interest from the photovoltaic community has concentrated on organic-inorganic hybrid halide perovskite absorbers, and nowadays, perovskite solar cells manifest their outstanding contribution among the low-cost photovoltaic technologies. Inevitably, large-area perovskite solar cells suffer a lot with their poor stability, hindering their commercialization pace. Thus, the implementation of concentrating photovoltaic technology in perovskite solar cells demonstrates an inherent advantage using a smaller size solar cell. This review provides an overview of concentrating photovoltaic technology implementation, including their recent research and development portfolio, their economic benefits in combination with inexpensive optical elements and tracking systems, limitations, challenges, and relative scope of the future study, focusing on the emerging perovskite solar cell technology. [ABSTRACT FROM AUTHOR]

Photo-physical properties of mechano-chemically synthesized organic-inorganic hybrid perovskites have been investigated. CH3NH3PbBr3 nano-particles were prepared using the wet ball milling technique. Three emission peaks have been observed using low temperature photoluminescence spectroscopy. We assign these peaks to originate from free excitonic (FE) and bound excitonic emission and impurity level transition. FE peak energy increases linearly with temperature and a lattice phase change (orthorhombic to cubic) induces a sudden lateral shift after 110 K. However, the simultaneous presence of two phases has not been observed in this case. Greater activation energy is found in the mechano-chemically synthesized material rather than reported solution processed samples which indicates higher excitonic stability. [ABSTRACT FROM AUTHOR]

In this manuscript, we have reported the crystal structure, dielectric response, and transport phenomenon of TiO2-V2O5 nanocomposites. The nanocomposites were synthesized using a sol-gel technique having different molar ratios of Ti:V (10:10, 10:15, and 10:20). The phase composition and the morphology have been studied using X-ray diffraction and field emission scanning electron microscope, respectively. The impedance spectroscopy studies of the three samples over a wide range of temperature (50 K–300 K) have been extensively described using the internal barrier layer capacitor model. It is based on the contribution of domain and domain boundary, relaxations of the materials, which are the main crucial factors for the enhancement of the dielectric response. The frequency dependent ac conductivity of the ceramics strongly obeys the well-known Jonscher's power law, and it has been clearly explained using the theory of jump relaxation model. The temperature dependent bulk conductivity is fairly recognized to the variable-range hopping of localized polarons. The co-existence of mixed valence state of Ti ions (Ti3+ and Ti4+) in the sample significantly contributes to the change of dielectric property. The overall study of dielectric response explains that the dielectric constant and the dielectric loss are strongly dependent on temperature and frequency and decrease with an increase of frequency as well as temperature. [ABSTRACT FROM AUTHOR]

In this work, CsPbBr3 has been successfully synthesized via sol-gel technique. The orthorhombic phase of the material has been verified by X-ray diffraction measurement followed by Rietveld refinement analysis. Morphological study has revealed the cubic shape of particles with dimension ∼3 μm. Electrical properties are characterized by Complex impedance (Z*), dielectric permittivity (ɛ*), and ac conductivity within the frequency range 10 Hz–5 MHz for different temperatures between 313K and 673 K. The dielectric behavior of CsPbBr3 is found to be thermally activated and frequency dependent. The ascensive nature of ɛ′(ω) at lower frequency is assigned to the Maxwell-Wagner type interfacial polarization. ɛ′(ω) has been fitted using Kramers-Kronig relation by including the dielectric constant at infinite frequency. Variation of ɛ″(ω) with frequency has been explained by the hopping of charge carrier over a potential barrier between charge defects. AC conductivity has also been fitted by Jonscher's power law to find the real component of conductivity and it has been described by using the Jump relaxation model. Activation energy has been calculated by fitting the dc conductivity using Arrhenius relation and found to have a value of 0.517 eV. Grain resistance (rg), grain capacitance (cg), grain boundary resistance (rgb), and grain boundary capacitance (cgb) have been accounted by fitting Z′ vs log(f) plot with equivalent circuit and existing theoretical model. [ABSTRACT FROM AUTHOR]