Search

Copper indium gallium selenide solar cells (CIGS-SCs) have gained attention due to their cost-effectiveness and environmentally friendly characteristics, making them a promising option for future electricity generation. The efficiency of CIGS-SCs can be enhanced by adding a back surface field layer (BSFL) under the absorber layer to reduce recombination losses. In this study, the electrical parameters, such as the series resistance, shunt resistance, and ideality factor, are calculated for CIGS-SCs with an advanced design, using the SC capacitance simulator (SCAPS) software. The detailed model used in the simulations considers the material properties and fabrication process of BSFL. By utilizing a reduced graphene oxide (rGO) BSFL, a conversion efficiency of 24% and a significant increase in the fill factor are predicted. This increase is primarily attributed to the ability of the rGO layer to mitigate the recombination of charge carriers and establish a quasi-ohmic contact at the metal-semiconductor interface. At higher temperatures, BSFL can become less effective due to an increased recombination and, in turn, a decreased carrier lifetime. Overall, this study provides valuable insights into the underlying physics of CIGS-SCs with BSFL and highlights the potential for improving their efficiency through advanced design and fabrication techniques. [ABSTRACT FROM AUTHOR]

A comprehensive investigation has been conducted on Ba(2-x)Sr(x)GdFeNb4O15 powders. These powders were synthesized through the conventional solid-state reaction. X-ray diffraction analysis at room temperature has demonstrated that the samples adopt the TTB-structure, exhibiting the space-group P4/mbm. The Raman spectra of the samples exhibit remarkable similarity, yet distinct bands at different wave numbers, indicative of the varying modes of the MO6 octahedra. The dielectric studies have uncovered intriguing findings, including a high dielectric constant and a broad permittivity peak. Remarkably, the Curie temperature varies with the substitution rate, yet remains frequency-independent, a clear indication of these materials' classical ferroelectric behavior. [ABSTRACT FROM AUTHOR]

A study was conducted to analyze Schottky contacts formed on p-isotype Zn(SSe)/GaAs heterostructures prepared by molecular beam epitaxy on p-GaAs(100) substrates. Deep level transient spectroscopy and photocurrent measurements were utilized to carry out the analysis. Results indicated that the threshold energies determined on a series of samples can be explained by absorption processes from the ZnSe and GaAs valence bands.

PbTiO3 (PT) sol gel processed powders doped with lanthanum (PLT14) and cerium (PLCexT14, x = 1; 3; 6; 10) were characterized by XRD and Raman spectroscopy. The samples crystallize in a pure perovskite phase at temperatures smaller than those reported for the same compounds prepared by other conventional methods. The effect of cerium or/and lanthanum on the crystal structure, microstructural and dielectric properties of PbTiO3 were investigated using FTIR, XRD, SEM, Raman spectroscopy and impedance spectroscopy. Incorporation of Ce reduces the temperature of crystallization of the samples, the temperature of the maximum of the permittivity and the diffuseness character of the ferroelectric to paraelectric transition, and enhances the permittivity.

The ginger sample has been exposed to X-rays at cumulative doses. The foodstuffs irradiation is used in particular to improve their hygienic qualities and increase their shelf lives. This process has been approved by various international organizations: FAO -- AIEA -- WHO. In the present work, we propose to reproduce by simulation, based on a quantum approach, of the ESR (Electron Spin Resonance) spectra. The semi-classical approach is valid for a simple system, but not for a complex system such as an atom with hyperfine structure. In this case a quantum approach, based on spin Hamiltonian, is essential to interpret the ESR spectra. The main result is that the simulated spectra are in good agreement with the experimental ones obtained before and after irradiation. [ABSTRACT FROM AUTHOR]

Fast Transform Fourier (FFT) is used to generate the EPR (electron paramagnetic resonance) spectra. For the simulated radical EPR spectrum data, the imaginary component of the data is zero, and the real value represents the strength of the radical EPR signal. The algorithm is simplified if N is chosen to be a power of 2, where N is the number of data points. Among advantages of this method is that complicated spectra can be simulated very quickly and with very little computer memory by performing convolutions in frequency space. We applied the FFT to simulate the EPR spectra of the [O = N·(SO3)2]2- radical anion and the CNC·HCOOH radical. Only the real parts of the Fourier transforms of the lineshape functions are taken into account and both Gaussian and Lorentzian lineshapes are supported. [ABSTRACT FROM AUTHOR]

Accurate estimation of photovoltaic (PV) panels' temperature is crucial for an accurate assessment for both the electrical and thermal aspects and performances. In this study we propose an advanced simulation approach linking a double-diode (DD) electrical model using the Artificial hummingbird algorithm; for parameter extraction; and a two-dimensional finite-difference-based thermal model. The electrical-sub model is firstly validated in comparison to experimental data figuring in literature using three types of PV technologies, with a relative error of about 2%. Then, the coupled model is validated using in-situ experimental setup consisting of the usage of thin-film PV technology, temperature sensors, weather station and an infrared camera. The results from both simulations and experiments exhibit strong alignment with a relative error of not higher than 2%; mainly due to the used material calibration uncertainties and external perturbations. This holistic model can be indeed further optimized, still, it has a potential to advance the development in the research area of PV systems.Future efforts could involve additional experimentation to validate the model for different seasons of the year., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)

We present a nanocalorimeter designed for the measurement of the dynamic heat capacity of thin films. The microfabricated sensor, the thermal conditioning of the sensor, as well as the highly stable and low noise electronic chain allow measurements of the real and imaginary parts of the complex specific heat with a resolution Δ C/C of about 10(-5). The performances of this quasi-differential nanocalorimeter were tested on a model of polymeric glass-former, the polyvinyl acetate (PVAc). The high stability and low noise of the device are essential for accurate studies on non-equilibrium slow relaxing systems such as glasses.