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Water-in-water (w/w) emulsions, comprising aqueous droplets within another continuous aqueous phase, rely on a low interfacial tension for stability. Thus far, it has been challenging to control their size and stability without the use of stabilizers. In this study, we introduce a microfluidic technique that addresses these challenges, producing stable w/w emulsions with precisely controlled size and uniformity. Results shows that using an acoustically actuated microfluidic mixer, PEG, Dextran, and alginate solutions (84.66 mPa.s viscosity difference) were homogenized rapidly, forming uniformly distributed w/w emulsions stabilized in alginate gels.The emulsion size, uniformity, and shear sensitivity can be tuned by modifying the alginate concentration. Biocompatibility was evaluated by monitoring the viability of kidney cells in the presence of emulsions and gels. In conclusion, this study not only showed emulsion formation with a high mixing efficiency exceeding 90 % for all viscosities, actuated at an optimized frequency of 1.064 MHz, but also demonstrated that an aqueous, solvent, and emulsifier-free composition exhibited remarkable biocompatibility, holding promise for precise drug delivery, cosmetics, and food applications.

Abstract Perovskite solar cells (PSCs) with evaporated gold (Au) electrodes have shown great efficiencies, but the maturity of the technology demands low-cost and scalable alternatives to progress towards commercialisation. Carbon electrode-based PSCs (C-PSCs) represent a promising alternative, however, optimising the interface between the hole transport layer (HTL) and the carbon electrode without damaging the underlying functional layers is a persistent challenge. Here, we describe a lamination technique using an isostatic press that can apply exceedingly high pressure to physically form an HTL/carbon interface on par with vacuum-evaporated electrodes, without damaging the device. Research-scale C-PSCs with a power conversion efficiency (PCE) of up to 20.8% are demonstrated along with large-area C-PSCs with PCEs of 19.8% and 16.9% for cell areas of 0.95 cm2 and 5.5 cm2, respectively. The unencapsulated C-PSCs significantly outperform the Au-electrode devices in accelerated operational stability testing (ISOS-L-1), retaining 84% of the initial PCE after 1000 h. Additionally, this versatile technique is also used to fabricate flexible, roll-to-roll printed C-PSCs with efficiencies of up to 15.8%.

Solar cells made by high temperature and vacuum processes from inorganic semiconductors are at a perceived cost disadvantage when compared with solution-processed systems such as organic and dye-sensitized solar cells. We demonstrate that totally solution processable solar cells can be fabricated from inorganic nanocrystal inks in air at temperature as low as 300 °C. Focusing on a CdTe/ZnO thin-film system, we report solar cells that achieve power conversion efficiencies of 6.9% with greater than 90% internal quantum efficiency. In our approach, nanocrystals are deposited from solution in a layer-by-layer process. Chemical and thermal treatments between layers induce large scale grain formation, turning the 4 nm CdTe particles into pinhole-free films with an optimized average crystallite size of ∼70 nm. Through capacitance–voltage measurements we demonstrate that the CdTe layer is fully depleted which enables the charge carrier collection to be maximized. [ABSTRACT FROM AUTHOR]

Passivation of CdSe semiconductor nanocrystals can be achieved by overcoating the particles with a homogeneous shell of a second semiconductor. Shell layers are grown in monolayer steps to ensure homogeneous growth of the shell. The relative band edges of the two materials determine the photoreactiveity of the resultant core-shell nanocrystals. The critical role of ligands in minimizing nucleation of the shell material during the growth of the passivating layer is emphasized. The delocalization of charge carriers into the shell layers can be followed spectroscopically during the growth processes. The relative spectral shifts are directly correlated to the relative energies of the band edges. [ABSTRACT FROM AUTHOR]