Recently, most of the record-breaking PSCs are used formamidinium lead triiodide (FAPbI3) as the perovskite absorber due to its narrow bandgap. To stabilize the α-phase of FAPbI3, one of the common ways is introducing MAPbBr3 (where MA is methylammonium) into the perovskite layer. However, the MA+ will sacrifice the thermal stability of devices, while the incorporation of Br– will enlarge the optical bandgap and eventually decreased the photocurrent of PSCs. Here, a convenient strategy is presented to sequentially deposit stable FAPbI3 perovskite layer without MA+/ Br– by introducing the two-dimensional (2D) perovskite materials PMACl. It is speculated that the PMACl can form a 2D structure in grain boundaries which plays the role of template for the growth of α-FAPbI3. In addition to tune the phase transition, the PMACl can improve the crystallization and smooth the morphology of perovskite. As a result, the PSCs with PMACl achieve a PCE of 16.19%, while the control device only exhibits a PCE of 10.67%. This novel method avoids introducing the MA+/ Br–, and provides a facile approach for the efficient FAPbI3 perovskite solar cells.
Recently, organic metal halide perovskites have attracted wide attention in the field of photovoltaic devices due to series of excellent photoelectric properties. However, the device performance is limited by a large number of surface defects in the perovskite film. Finding an effective method for defect passivation of perovskite film is considered to be a preferred strategy to further improve the performance of perovskite photovoltaic devices. Here, we use an organic metal salt, sodium alginate (SA), to passivate the surface defects of perovskite films to prepare high-performance perovskite photodetectors (PePDs). We find that the introduction of SA can improve the quality of perovskite active layer and passivate the surface defects effectively, which reduce the carrier recombination probability to increase the photocurrent and reduce the dark current of the PePDs. And the detectivity (D*) at 600 nm reaches 3.6×1012 Jones, three times that of the controlled devices. Meanwhile, the PePDs doped with sodium alginate have better stability and device life, which remains 82% of the original performance after being placed in the atmosphere for 7 days. These results indicate that it is an effective strategy to passivate perovskite film with organic metal salt to prepare high-performance PePDs.
For microseparation devices, the quality of the microholes, e.g., smooth surfaces and edges, is of crucial importance for high-performance separating ability. Here, we used water-assisted femtosecond laser perforating technology to fabricate high-quality size-controllable (from several to tens of micrometers) micropore arrays on ultrathin aluminum foil surface, which have smooth edges without fragments and debris. The micropore arrays can effectively filtrate particles with diverse diameters. Compared to the micropores prepared in air under the same laser processing parameters, the water-assisted micropores have greatly improved the surface quality, and the particle separation ratio can be increased by ∼40 % . This method for preparing high-quality micropore arrays can also be applied to other sheet materials, such as titanium, silicon, and even plastic, and so on, which can be widely used in the fields of microfluidic devices for microseparation.
The shape of manufactured microtubes is one of the most important properties in their numerous emerging applications areas, like drug delivery, microfluidics, and cell biology. However, making non-cylindrical microtubes with 3D features in a reproducible and single-step fashion, and meanwhile, with the ability of remote control has remained challenging. In this study, we demonstrate the controlled synthesis of highly curved 3D microtubes by two-photon polymerization with single exposure of structured optical vortices, which is generated by phase modulation with a liquid crystal spatial light modulator (SLM). We exploit the tight focusing property of the optical vortices along the light path to create 3D microtubes. By modulating the topological charge and symmetry of the optical vortices, the size and geometry of fabricated microtubes can be well controlled. Finally, we combine these two ideas with the use of magnetic nanoparticles doped resist to fabricate 3D microtubes with elaborate features and remote controllability. Precise rotation and motion of the microtubes are realized by external magnetic field. With the fabricated functional mocrotubes, elaborate capture, delivery, and realease of microparticles are demonstrated. The technology we introduce is simple, stable and achieves a high production rate to make a wide variety of functional 3D microtubes, which have broad applications in cargo transportation, drug delivery, biosensing, microfluidics, and targeted cell therapy.
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