Photovoltaic properties of new solar cell based on ideal cubic NaNbO3 thin films: a combined experimental and density functional theory study.

We explore the photovoltaic properties of a novel homojunction solar cell based on NNO(p)/NNO(n) perovskite by employing a combination of material synthesis, characterization and density functional theory calculations that are novel ideas compared to those previously reported in the literature. The band structure reveals that NaNbO3 introduces a n-type semiconductor. Moreover, using DFT calculation, we created n-NNO by a simple substitution in the O site by 4.16% fluorine atoms. Experimental and DFT calculation reveals that NNO perovskite exhibits a direct bandgap of ∼1.6 eV, with a slightly larger two other direct bandgaps of ∼2.13 and 3.24 eV. After extracting the necessary parameters, an electrical modelization of an n-NNO/p-NNO solar cell is performed by Maple software revealed that the cell conversion efficiency can reach 17% which presents a first path to identify a new solar cell based only on perovskite material.

Optical and dielectric properties of silver-substituted ZnAl2O4 spinels synthesized using a sol-gel auto-combustion method.

The present study deals with two compounds, (x = 0.05 and x = 0.1), synthesized using a sol-gel auto-combustion method. X-ray diffraction analysis and Fourier transform infrared spectroscopy confirmed the formation of a spinel structure. UV-visible spectroscopy revealed that the band gap is 4.3 eV and 4 eV for x = 0.05 and x = 0.1, respectively, which confirm that these compounds, (x = 0.05 and x = 0.1), are potential candidates for optoelectronics. Moreover, the effect of frequency and temperature on the dielectric parameters was studied using impedance spectroscopy. Additionally, the activation energies were estimated from the modulus data and are about 0.659 eV for x = 0.05 and 0.41 eV for x = 0.1. These values are in good agreement with those obtained from complex polarizability.

Structural, morphological, and electrical properties of silver-substituted ZnAl2O4 nanoparticles.

In this paper, nanoparticles of (x = 0.05 and x = 0.1) were synthesized by the sol-gel auto-combustion method and characterized by various techniques. X-ray diffraction (XRD) for structural characterization confirms the successful formation of a cubic spinel structure with the space group Fd3̄m. Their morphology was evaluated with a scanning electron microscope (SEM) which shows an agglomeration of nanoparticles. To characterize the electrical behavior of our compounds, we used impedance spectroscopy at temperatures ranging from 313 K to 653 K and frequencies ranging from 0.1 Hz to 1 MHz. The experimental data for the real and imaginary impedance parts were mounted on the equivalent grain resistance (R g)//fractal capacitance (CPE) circuit. Indeed, the activation energies extracted from the electrical conductivity and the resistance of the grain resistance (R g) closed and confirmed a transformation of the electrical behavior confirmed by a decrease in the resistance of the materials. The study of the alternating conductivity shows a Jonscher curve behavior and a thermally activated conduction process. The variation of the exponent "s" as a function of temperature shows, on the one hand, the presence of two models of conduction correlated barrier jump (CBH) and non-overlapping small polaron tunneling (NSPT) for x = 0.05 and, on the other hand, a CBH model for x = 0.1.

Investigation of temperature and frequency dependence of the dielectric properties of multiferroic (La0.8Ca0.2)0.4Bi0.6FeO3 nanoparticles for energy storage application.

In this work we synthesized the multifunctional (La0.8Ca0.2)0.4Bi0.6FeO3 material using a sol-gel process. Structural and morphologic investigations reveal a Pnma perovskite structure at room temperature with spherical and polygonal nanoparticles. A detailed study of the temperature dependence of the dielectric and electrical properties of the studied material proves a typical FE-PE transition with a colossal value of real permittivity at 350 K that allows the use of this material in energy storage devices. Thus, the investigation of the frequency dependence of the ac conductivity proves a correlated barrier hopping (CBH) conduction mechanism to be dominant in the temperature ranges of 150-170 K; the two observed Jonscher's power law exponents, s 1 and s 2 between 180 K and 270 K correspond to the observed dispersions in the ac conductivity spectra in this temperature region, unlike in the temperature range of 250-320 K, the small polaron tunnel (NSPT) was considered the appropriate conduction model.