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Copper indium sulfide quantum dots (QDs) have attracted substantial attention in recent years due to environmental issues and diverse applications. We report the synthesis and characterization of c...

One of the major drawbacks in dye-sensitized solar cells (DSSC) is related to the use of a liquid electrolyte, which limits durability and stability. Part of this problem can be solved by replacing the liquid electrolyte by a polymer or gel electrolyte, although the open circuit potential (VOC) of the solar cells is affected. In this work, the role of the reduced graphene oxide (RGO) added to a gel electrolyte in order to improve the efficiency of DSSCs is discussed in detail. The gel polymer electrolyte is composed of poly(ethylene oxide) (PEO), γ-butyrolactone (GBL), LiI, I2, and different concentrations of RGO. The best solar cell using 0.5 wt % of RGO delivered an efficiency of 5.07 ± 0.97%, with the highest values of Isc and VOC. RGO sheets are acting as a multipurpose component in the electrolyte. The recovery of the VOC values can be related to the removal of polyiodide species from the photoanode surface by interaction with the RGO sheets. The increase in the Isc is assigned to the enhancement in ...

We report a quantitative wavelength-resolved analysis (460–600 nm) of the two-photon absorption (2PA) cross-section of water-soluble MPA-capped ZnS quantum dots (QDs). For that, we employed the open-aperture Z-scan technique using an amplified femtosecond laser system operating at low repetition rate (1 kHz). MPA-capped ZnS QDs with size distribution centered at ca. 3.8 nm were synthesized using the one-step aqueous procedure. The molar absorptivity of the lowest energy one-photon transition from ZnS QDs (1S3/2(h) → 1S(e)) was estimated in ∼6.5 × 104 M–1 cm–1. Nonlinear spectroscopic data showed that ZnS QDs present 2PA in the region between 4.15 and 4.35 eV (2hν) due to the 1S1/2(h1) → 1P3/2(e) low energy transition. Furthermore, two 2PA bands centered at 4.68 and 5.25 eV (2hν), associated with higher energy excitonic transitions, were also observed. The 2PA cross-section values along the entire spectral region measured (2hν = 4.15 to 5.4 eV) are in the order of 102 Goeppert–Mayer units. By means of a th...

Theoretical calculations were used for understanding the occlusion of the Jacobsen’s catalyst inside a polydimethylsiloxane/tetraethoxysilane (PDMS/TEOS) polymeric membrane. Our analysis indicates there is a partition equilibrium of the catalyst between the solvent and the swelled membrane. Density functional theory calculations at the B3LYP level predict interaction energies of the Jacobsen’s catalyst with benzene, chlorobenzene, dichloromethane, tetrahydrofuran, and acetone and with a model of PDMS chain in the range of 6−8 kcal mol−1. For methanol, the hydrogen bonding involving the coordinated chloride atom reaches 14 kcal mol−1. These findings were used for designing a new membrane, where a diol structure was added to the side of the polymeric chain. The modified membrane should present improved retention properties.