Concentrator photovoltaic (CPV) systems have displayed an important cost reduction and in the next few years could offer a competitive cost advantage compared to that of flat plate PV systems. Such CPV systems require some cooling methods to overcome high operating temperatures, which reduces their efficiency significantly. On the other hand, thermoelectric generators (TEG) are devices that convert thermal energy directly to electrical energy, provided that there is a temperature difference between its two faces. A hybrid concentrator photovoltaic/thermal (CPV/T) system is proposed in this work. Such a system uses TEG in a two-fold manner: to passively cool down the CPV cell in order to maintain its power conversion efficiency in such high temperature conditions, and to use the accumulated thermal energy to generate electrical energy, which is added to the system’s total power output. Two types of solar cells were investigated, namely, Ga_0.35In_0.65P/Ga_0.83In_0.17As with efficiency an of 28% at 250X, and a Laser Grooved Buried Contact (LGBC) silicon concentrator PV cell with an efficiency of 18.3% at 40X. These cells are assumed to be coupled with two TEGs of the same type but with a different number of junctions. Experimental results showed that coupling TEG modules to a CPV system could be a useful method for enhancing the overall output power, provided that PV cells are chosen with a low efficiency temperature coefficient and high PV performance. Also, TEG modules have to be chosen with a high figure of merit. Moreover, the operating optical concentration ratio, as well as the covered area of the TEG, have to be optimized in order to maximize the total system output.

This paper reports the effect of Nickel (Ni) on indium sulfide (In₂S₃) powder. This work presents a systematic study of the physical and dielectric properties of In_2-xS₃Ni_x powders with 0, 2, 4, and 6 at.% of nickel. Doped and undoped samples were investigated by X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy, thermal gravimetric analysis, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and impedance spectroscopy. XRD patterns revealed that each In_2-xS₃Ni_x composition was crystalline, which was also confirmed by the FTIR results. The presence of Ni in the samples was confirmed by energy dispersive spectroscopy (EDS). The Raman studies show different peaks related to the In₂S₃ phase and do not reveal any secondary phases of In–Ni and Ni–S. The SEM images of the undoped and Ni-doped In₂S₃ samples indicated a correlation between dopant content and the surface roughness and porosity of the samples. The impedance analysis indicated semiconductor behavior present in all samples, as well as a decrease in resistance with increasing Ni content. This work opens up the possibility of tailoring the properties and integrating Ni-doped In₂S₃ nanocomposites as thin film layers in future solar cells.

In order to maximize the output of concentrator Photovoltaic cells and maintain their efficiencies, the operating temperature of concentrator photovoltaic cells must be reduced. A way that could reduce such photovoltaic temperature is by thermally attaching them on top of a thermoelectric generator. A thermoelectric generator in such coupling will act as a low-cost passive-cooling subsystem, as well as a power generator for producing additional energy from the rejected photovoltaic heat. Increasing the area of the proposed photovoltaic cells relative to the thermoelectric generator’s hot-side area will result in an increase in the thermoelectric generator’s electrical output, but may also result in overheating the photovoltaic cells, hence reducing their performance. Optimization has to be performed for the photovoltaic covering percentage relative to the hot-side area in order to maximize the output of the whole coupled system. This work investigates the electrical and thermal performance of thermoelectric generators in the case of partial illumination of their hot side. Experiments have been carried out using three thermoelectric generator modules with different areas, and under two levels of concentrated illumination. The thermoelectric generator output voltage, current, and temperature have been measured, and the figure-of-merit and maximum power of the thermoelectric generator (TEG) has been calculated and demonstrated.

We investigated the formation of photovoltaic (PV) devices using direct n-Si/MAPI (methylammonium lead tri-iodide) two-sided heterojunctions for the first time (as a possible alternative to two-terminal tandem devices) in which charge might be generated and collected from both the Si and MAPI. Test structures were used to establish that the n-Si/MAPI junction was photoactive and that spiro-OMeTAD acted as a “pinhole blocking” layer in n-Si/MAPI devices. Two-terminal “substrate” geometry devices comprising Al/n-Si/MAPI/spiro-OMeTAD/Au were fabricated and the effects of changing the thickness of the semitransparent gold electrode and the silicon resistivity were investigated. External quantum efficiency and capacitance–voltage measurements determined that the junction was one-sided in the silicon—and that the majority of the photocurrent was generated in the silicon, with there being a sharp cutoff in photoresponse above the MAPI bandgap. Construction of band diagrams indicated the presence of an upward valence band spike of up to 0.5 eV at the n-Si/MAPI interface that could impede carrier flow. Evidence for hole accumulation at this feature was seen in both Kelvin-probe transients and from unusual features in both current–voltage and capacitance–voltage measurements. The devices achieved a hysteresis-free best power conversion efficiency of 2.08%, V $_{\rm OC}$ 0.46 V, J $_{\rm SC}$ 11.77 mA/cm2, and FF 38.4%, demonstrating for the first time that it is possible to create a heterojunction PV device directly between the MAPI and n-Si. Further prospects for two-sided n-Si/MAPI heterojunctions are also discussed.

A p–n heterojunction film consisting of p-type CuFe₂O₄ and n-type ZnFe₂O₄ was fabricated in this study. The n-type ZnFe₂O₄ film was deposited on a stainless steel substrate using the spray pyrolysis method, after which a top layer of p-type CuFe₂O₄ thin film was deposited and annealed. Characterization techniques, such as X-ray diffraction, scanning electron microscopy, UV–Vis diffuse reflectance spectroscopy, and photoluminescence, confirmed the formation of a superlattice p–n heterojunction between CuFe₂O₄ and ZnFe₂O₄. Photoelectrochemical measurements were conducted to investigate the photoelectrochemical properties of the samples, resulting in a photocurrent of 1.2 mA/cm² at 1.5 V (vs. Ag/AgCl) under illumination from a 100-watt LED light source. Utilizing the p–n junction of CuFe₂O₄/ZnFe₂O₄ as a photoanode increased the hydrogen production rate by 30% compared to that of the dark measurement. This enhancement in performance was attributed to the potential barrier at the p–n heterojunction interface, which improved the separation of photoinduced electron–hole pairs and facilitated a more efficient charge transfer. Additionally, coating the stainless steel electrode with this ferrite sample improved both the corrosion resistance and the stability of hydrogen production over extended operation times.

This study presents the first successful integration of Fe₃O₄ and Li_0.5Cr_0.5Fe₂O₄ into a well-defined core/shell nanostructure through a two-step synthesis that combines co-precipitation and sol–gel auto-combustion methods. Unlike conventional composites, the core/shell design effectively suppresses the magnetic dead layer and promotes exchange coupling at the interface, leading to enhanced saturation magnetization, superior magnetic heating (specific absorption rate; SAR), and improved dielectric properties. Our research introduces a novel interfacial engineering strategy that simultaneously optimizes both magnetic and dielectric performance, offering a multifunctional platform for applications in magnetic hyperthermia, electromagnetic interference (EMI) shielding, and microwave devices.