Water has been labeled as a devil in fabrication and stability of perovskite solar cells. The inherent cognition impels researchers to prepare perovskite films in water-controlled conditions. Herein, water is used as a green solvent to prepare CsPbBr3 films through a two-step spin-coating method. Due to the high solubility of CsBr but low solubility of PbBr2 in water, it provides a possibility to deposit CsBr onto PbBr2 from water solution without destroying the film. Here, high-quality CsPbBr3 films are fabricated by spin-coating concentrated CsBr/H2O solution onto the PbBr2 film followed by annealing. As a result, the solar cells basing on a configuration of FTO/TiO2/CsPbBr3/Carbon exhibit a power conversion efficiency of 6.12%. This work provides a simple and easy way to prepare high-quality CsPbBr3 films for efficient solar cells. It makes a solid step toward reducing the solvent toxicity in the fabrication process of perovskite solar cells. It also breaks the forbidden zone for fabricating perovskite films from water and updates the inherent understanding of water in the research study of perovskite solar cells.

Toxic solvents used in the fabrication of perovskite solar cells are an obstacle for their commercialization. Replacing those toxic solvents with green solvents is very important for both ecological environment safety and the health of operators working in manufactory and labs. CsPbBr3‐based solar cells have attracted increasing attention due to its high stability. Herein, high‐quality CsPbBr3 films are prepared using all green solvents based on a two‐step spin‐coating method. In the first step, a green solvent system of polyethylene glycol (PEG) with the addition of γ‐butyrolactone is used for preparing PbBr2 solutions by matching the Hansen solubility parameters (HSPs) between PbBr2 and the mixed solvent system. By optimizing the HSPs and viscosity, a new complex of PbBr2·(PEG) is formed by spin‐coating from the PbBr2 solution, followed by acetic acid dropping while spinning. In the second step, green water is used to dissolve CsBr to prepare a high concentration CsBr/H2O solution. High‐quality CsPbBr3 films with full coverage are obtained by spin‐coating CsBr/H2O solution onto the PbBr2·(PEG) films after annealing. As a result, a solar cell with configuration of fluorine‐doped tin oxide/TiO2/CsPbBr3/carbon exhibits a power conversion efficiency of 8.11% due to its high‐quality harvest layer.

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CsPbBr3 films have attractive applications in resistive switching memory, light-emitting diodes, photodetectors, and especially in perovskite solar cells (PSCs) because of their high stability and ease of fabrication in open...

Exosomes are essential early biomarkers for health monitoring and cancer diagnosis. A prerequisite for further investigation of exosomes is the isolation, which is technically challenging due to the complexity of body fluids. This paper presents the development of an integrated microfluidic chip for exosomes isolation, which combines the traditional immunomagnetic bead-based protocol and the recently emerging microfluidic approach, resulting in benefits from both the high-purity of the former and the automated continuous superiority of the latter. The chip was designed based on an S-shaped micromixer with embedded baffle. The excellent mixing efficiency of this micromixer compared with Y-shaped and S-shaped micromixers was verified by simulation and experiments. The photolithography technique was employed to fabricate the integrated microfluidic chip, and the manufacturing process was elucidated. We finally established an experimental platform for exosomes isolation with the fabricated microfluidic chip built in. Exosomes isolation experiments were conducted using this platform. The distribution and morphology of the isolated exosomes were observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Quantitative size analyses based on transmission electron micrographs indicated that most of the obtained particles were between 30 and 150 nm. Western blot analyses of the isolated exosomes and the serum were conducted to verify the platform’s capability of isolating a certain subpopulation of exosomes corresponding to specified protein markers (CD63). The complete time for isolation of 150 μL serum samples was approximately 50 min, which was highly competitive with the reported existing protocols. Experimental results proved the capacity of the established integrated microfluidic chip for exosomes isolation with high purity, high integrity, and excellent efficiency. The platform can be further developed to make it possible for practical use in clinical applications as a universal exosomes isolation and characterization tool.

Toxic solvents used in the fabrication of perovskite films are a non-ignorable obstacle for the commercialization of perovskite solar cells (PSCs). CsPbBr3 based solar cells have attracted increasing attentions due...

Cellular mechanical properties are closely related to cell physiological functions and status, and their analysis and measurement help understand cell mechanism. In this study, a microfluidic platform was built to measure the mechanical properties of cells by using dielectrophoretic (DEP) force. The electrodes generally used to stretch cells are made of indium tin oxide, Au, and Pt, which have inherent disadvantages. In this paper, galinstan alloy liquid metal was first introduced as microelectrode to form non-uniform electric filed for red blood cell stretching manipulation. The liquid metal microelectrode is easy to manufacture, low in price, stable at high voltage, and reusable. An effective microfluidic chip integrated with liquid metal electrode was designed and simulated, and a series of experiments to capture and stretch red blood cells was performed. The length of the red blood cells increased from 6 µm to 8 µm under the DEP force from 0 pN to 103 pN. This work also revealed the potential use of liquid metal as microelectrode to manipulate the microparticles and cells in a microfluidic chip. INDEX TERMS Liquid metal electrode, galinstan, dielectrophoresis, microfluidic chip, cell stretching.

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