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It is imperative to transform the sub-bandgap photons into higher energy photons that can significantly enhance the efficiency of the photovoltaic device. Upconverting nanoparticles (UCNPs), combine (sub-bandgap) photons to give high-energy photons. Hexagonal UCNPs of β-NaYF4 concurred with Yb3+ and Er3+ were prepared via thermal decay of metals trifluoroacetate precursors. A solvothermal method was used for the preparation of Ru3-(BTC)2 MOF. The precursors were mixed in a molar ratio 3RuCl3xH2O: 2H3btc:5CH3COOH: 925H2O. The prepared materials were characterized by X-ray diffraction, SEM, TEM, UV–V is absorption, and emission spectra. The solar cell ZnO/MOF/UCNPs Electrode was prepared by the deposition of MOF on the ZnO electrode by the spin coating method and annealed at 200 °C for 2 h. Then this electrode was immersed into 40 mM UCNPs for 24 h then heated to 400 °C to form a compact layer of UCNPs. The impact of β-NaYF4:Yb3+, Er3+ UCNPs on the performance of ZnO/MOF photoelectrode was studied through solar cell assembly in a sandwich structure. The results showed that the UCNPs-based MOF-solar cell exhibited a 15.6% increase in the photocurrent and a 22% increase in the power conversion efficiency compared with MOF sensitized solar cell (MOFSSC) without UCNPs. This enhancement could be due to the presence of the UCNPs that extends the spectral response range of MOF-SSC to the NIR region. So integrating up-converting materials into MOF-sensitized solar cells would generate a new kind of highly efficient solar cells that realize the utilization of the solar light energy in a broad spectrum from the UV to the NIR region.

Mn3O4 (M) incorporated graphenes (G) synthesized by a deposition–solvothermal process, formed at various nominal weight percentages (G1M1, G3M1 and G1M3), were efficiently used for the photodegradation of methylene blue dye (MB) under visible light illumination (λ > 420 nm, 88 W, 20 ppm, 298 K) and under microwave irradiation (800 W, 2.45 GHz, 373 K). These materials were characterized using XRD, TEM-SAED, UV-Vis diffuse reflectance, N2 sorptiometry, FTIR and Raman techniques. Amongst the nanocomposites, G3M1 of polyhedral structure and an average domain equal to 10–12 nm has presented unique photo-degradation performance (100% degradation, 60 min, 0.0791 min−1 and TOC of 60%) exceeding the rest of the materials. This was mainly due to the extraordinary optical properties and to the strong interaction between Mn3O4 and graphene through which charge recombination is hampered. Based on the conduction and valence band edges together with the studied reactive species, it has been shown that ˙OH was the dominant species responsible for the MB degradation. Interestingly, the G3M1 nanocomposite has shown fascinating microwave absorption properties and is capable of degrading MB at a faster rate (0.287 min−1) than the one conducted via photocatalysis. Scavenger studies have shown that ˙OH and electrons were responsible for the excellent performance of the MB microwave degradation. The microwave results were discussed in view of the marked increase in dielectric constant (e−) and dielectric loss (e′′) in the studied frequency range of 1.0 Hz to 100 kHz, in addition to the electronic conductivity measurements. This work offers an exceptional approach for exploring high-performance microwave absorption as well as distinctive visible light photocatalytic reaction for organics degradation.

We have developed dye-sensitized nanocrystalline CdS and ZnS solar cells (DSSCs) based on crystal violet, methylene blue, and fluorescein photosensitizers. Nanocrystalline CdS and ZnS were synthesized by a green synthesis method using starch as the capping agent. Characterization of nanocrystalline CdS and ZnS was carried out by optical absorption and x-ray diffraction. The results indicate that CdS and ZnS prepared by this method may be used as photoelectodes in photo-electro-chemical energy conversion systems. DSSCs have been built and their photocurrent, open-circuit voltage, fill factor, and efficiency have been measured under direct sunlight illumination (1000 Wcm−2). The efficiency of the cells made from dye-CdS was much higher than that of the cells made from dye-ZnS. This can be attributed to the particle size effect. Among the prepared dye-sensitized solar cells, a DSSC based on fluorescein dye as the photosensitizer produced the highest overall light solar energy to electricity conversion efficiency.

CdS quantum dot (QD) solar concentrators were prepared by a sol–gel spin coating method. Thin films were prepared at different annealing temperatures and characterized by X-ray diffraction and spectroscopic techniques. The effect of temperature on the optical properties of CdS QDs embedded in silica matrix was assessed before and after exposure of the samples to sunlight for up to 4 weeks. The results show that as the annealing temperature increases, the fluorescent intensity and Stokes shift decrease. Therefore lower temperatures are preferable for the preparation of highly efficient QD solar concentrator systems.

Oxidative stress is a basic mechanism behind the development of diabetic retinopathy (DR). Therefore, the present study conducted to evaluate the protective effect of zinc oxide nanoparticles (ZnONPs) doped with fluorine (F:ZnO) and chlorine (Cl:ZnO), on retinal oxidative stress in type II diabetic rats. TEM showed that the F:ZnO and Cl:ZnO have average particle size 17.7 and 59.3 nm, respectively. The results indicated that serum glucose was increased significantly (p ≤ 0.05) and serum insulin was decreased significantly 3 days after treatment with STZ compared to other groups. STZ treatment depleted both retinal and liver TBA and retinal GST contents. While, simultaneous treatment rats with low and high dose of STZ + F:ZnO and STZ + Cl:ZnO were decreased serum glucose induced by STZ and reversed the deplete influence on GSH level of retinal and reduced the highs in TBA levels of livers and retinas in STZ -administrated rats. The results investigate the useful effects of high dose of F:ZnO and Cl:ZnO in protection diabetic rats against hyperglycemia and retina against oxidative stress.

Luminescent solar concentrator samples using polymethylmethacrylate (PMMA) as the matrix with phthalocyanine, nickel-phthalocyanine and hematoporphyrin IX dichloride laser dyes were prepared by a casting method. Optical absorption measurements were carried out at room temperature across the 200–900 nm wavelength region both before and after the samples were exposed to sunlight for two weeks. The degradation of PMMA–dye samples, measured by absorption, was found to obey a first-order kinetic equation. Values of the optical band gaps ( E g ) have been obtained for the direct allowed transitions before and after the samples were exposed to sunlight. The tail width of localized states in the band gap ( E u ) was calculated from Urbach’s formula. Photodegradation studies revealed that the phthalocyanine dye systems are the most stable. Emission spectra and quantum efficiency were also investigated, and phthalocyanine dyes were shown to have a lower Stokes shift and a higher fluorescence quantum yield ( Q f ) than the hematoporphyrin IX dichloride. Collectively, these results suggest that PMMA doped with phthalocyanines provide the better system for use in fluorescent solar collector systems.

Thin film and sheet PbS quantum dots (QDs) concentrators were synthesized by sol-gel method using three different PbS concentrations (0.14, 0.2, and 0.4 mol%). The structure and morphology of the prepared PbS QDs were characterized by X-ray diffraction (XRD), Scan electron microscopy (SEM), and Transmission electron microscopy (TEM). The photostability of the PbS QDs concentrators under outdoor exposure to sunlight for 8 weeks was studied. The results showed that the PbS QDs sheet with PbS concentration (0.14 mol%) has the highest luminescence intensity. The sheet PbS QDs concentrator was used to couple with PV solar cell and the corresponding photoelectric conversion efficiency was measured under sun light illumination. I-V characteristics of the photovoltaic devices, both open circuit voltage and short circuit current were improved as compared to the device without collector. This indicates that the proposed technique is very useful for improving the efficiency of solar cell.

This work presents an experimental and theoretical study of cyanidin natural dye as a sensitizer for ZnO dye-sensitized solar cells. ZnO nanoparticles were prepared using ammonia and oxalic acid as a capping agent. The calculated average size of the synthesized ZnO with different capping agents was found to be 32.1 nm. Electronic properties of cyanidin and delphinidin dye were studied using density functional theory (DFT) and time-dependent DFT with a B3LYP/6-31G(d,p) level. By comparing the theoretical results with the experimental data, the cyanidin dye can be used as a sensitizer in dye-sensitized solar cells. An efficiency of 0.006% under an AM-1.5 illumination at 100 mW/cm(2) was attained. The influence of dye adsorption time on the solar cell performance is discussed.