Pharmaceutical cocrystals are a promising technology that can be used to improve the solubility of poor aqueous compounds. The objective of this study was to systematically investigate the solubility of myricetin (MYR) cocrystals, including their kinetic solubility, thermodynamic solubility, and intrinsic dissolution rate (IDR). The effects of pH, surfactant, ion concentration, and coformers on the cocrystal solubility were evaluated. Furthermore, single crystal structures of MYR, myricetin–isonicotinamide (MYR–INM) and myricetin–caffeine (MYR–CAF) cocrystals were analyzed to discuss the possible reasons for the enhancement of cocrystal solubility from the perspective of the spatial structure. The results indicated that the kinetic solubility of MYR cocrystals was modulated by pH and cocrystal coformer (CCF) ionization in buffer solution, while it primarily depended on the CCF solubility in pure water. In addition, the solubility of MYR cocrystals was increased in a concentration dependent fashion by the surfactant or ion concentration. The thermodynamic solubility of MYR–INM (1:3) cocrystals decreased with the increases of the pH value of the dissolution media. The IDR of MYR cocrystals was faster than that of MYR in the same medium and extremely fast in pH 4.5 buffer. The improved solubility of MYR cocrystals was probably related to the alternate arrangements of MYR and INM/CAF molecules and increased intermolecular distance. The present study provides some references to investigate the solubility behavior of pharmaceutical cocrystals.
In this work, we demonstrate a four-terminal tandem solar cell consisting of a luminescent solar concentrator (LSC) based on silicon quantum dots (SiQDs) in front of a 4 cm × 4 cm perovskite solar cell (PSC). The LSC front surface is uniformly covered with a nanoporous poly(methyl methacrylate) (PMMA) antireflection coating, which can enhance the transmission by up to 3% from the visible to the near-infrared range. The colloidal SiQDs inside the LSC primarily absorb the UV portion of the solar irradiation, re-emitting red fluorescence, which propagates to the waveguide edges for generating electricity while allowing the rest of the incident sunlight to be absorbed in the back PSC. With an air gap between the SiQD-LSC and PSC, compared to the bare PSC, the two devices in combination exhibits significant external quantum efficiency (EQE) enhancement under 365 nm UV illumination, but shows no power conversion efficiency (PCE) enhancement under xenon arc lamp illumination. In contrast, when the air gap is removed, the SiQD-LSC becomes a luminescent downshifter than a concentrator, with most of the SiQD fluorescence being absorbed by the back PSC. In this case, the SiQD-LSC/PSC tandem solar cell can achieve up to 6.2% PCE enhancement over the bare PSC at low SiQD concentrations. Particularly, at 1.08 mg mL −1 , although the tandem solar cell has about the same PCE as the bare PSC, the front SiQD-LSC absorbs 69% of the solar UV, making the back PSC more stable than the bare PSC.
A poly(methyl methacrylate) (PMMA) bilayer antireflective coating (ARC) is designed based on polymeric microphase separation and matrix-assisted pulsed laser evaporation (MAPLE). The spin-coated layer shows subwavelength porous network structures, after phase separation via annealing and removal of the polystyrene (PS) phase, while the MAPLE deposited surface layer exhibits a biomimic moth-eye structure on glass to trap the incident light. The elaborate spin coated structure can be controlled flexibly by changing the ratio of mixture, annealing time and temperature, and the moth-eye structure can also be tuned by deposition parameters. The transmittance of the ARC presents a maximum of 95.64% and an average of 94.81% in visible range. The moth-eye structure on glass substrate formed by nanoglobules makes positive contributions to the improvement of transmittance according to UV–Vis result and simulation. The wetting motion of PMMA globules is observed as well by the comparison of AFM surface morphologies and cross-sectional profiles of globules on glass and polymer thin film. This work is a novel attempt to fabricate bilayer ARC with two different structures by a single polymeric material and will provide new route for fabrication of multilayer ARCs.
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