No abstract

Despite recent progress in producing perovskite nanowires (NWs) for optoelectronics, it remains challenging to solution‐print an array of NWs with precisely controlled position and orientation. Herein, we report a robust capillary‐assisted solution printing (CASP) strategy to rapidly access aligned and highly crystalline perovskite NW arrays. The key to the CASP approach lies in the integration of capillary‐directed assembly through periodic nanochannels and solution printing through the programmably moving substrate to rapidly guide the deposition of perovskite NWs. The growth kinetics of perovskite NWs was closely examined by in situ optical microscopy. Intriguingly, the as‐printed perovskite NWs array exhibit excellent optical and optoelectronic properties and can be conveniently implemented for the scalable fabrication of photodetectors.

Conductive coatings show great promise for next-generation electromagnetic interference (EMI) shielding challenges on textile; however, their stringent requirements for electrical conductivity are difficult to meet by conventional approaches of increasing the loading and homogeneity of conductive nanofillers. Here, the axial alignment of carbon nanotubes (CNTs) on fibers that were obtained by spontaneous capillary-driven self-assembly is shown on commercial cotton fabrics, and its great potential for EMI shielding is demonstrated. The aligned CNTs structurally optimize the conductive network on fabrics and yield an 81-fold increase in electrical conductivity per unit of CNT, compared with the disordered CNT microstructure. The high-efficiency electrical conductivity allows a several-micron-thick coating on insulating fabrics to endow an EMI shielding effectiveness of 21.5 dB in the X band and 20.8 dB in the Ku band, which meets the standard shielding requirement in commercial applications. It is among the minimum reported thicknesses for conductive nanocomposite coatings to date. Moreover, the coated fabrics with aligned CNTs possess a desirable stability upon bending, scratching, stripping, and even washing, which is attributed to the dense CNT packing in the aligned microarchitecture. This work presents the anisotropic structure on large areas by self-assembly, offering new opportunities for next-generation portable and wearable electronic devices.

Despite recent rapid advances in metal halide perovskites for use in optoelectronics, the fundamental understanding of the electrical‐poling‐induced ion migration, accounting for many unusual attributes and thus performance in perovskite‐based devices, remain comparatively elusive. Herein, the electrical‐poling‐promoted polarization potential is reported for rendering hybrid organic–inorganic perovskite photodetectors with high photocurrent and fast response time, displaying a tenfold enhancement in the photocurrent and a twofold decrease in the response time after an external electric field poling. First, a robust meniscus‐assisted solution‐printing strategy is employed to facilitate the oriented perovskite crystals over a large area. Subsequently, the electrical poling invokes the ion migration within perovskite crystals, thus inducing a polarization potential, as substantiated by the surface potential change assessed by Kelvin probe force microscopy. Such electrical‐poling‐induced polarization potential is responsible for the markedly enhanced photocurrent and largely shortened response time. This work presents new insights into the electrical‐poling‐triggered ion migration and, in turn, polarization potential as well as into the implication of the latter for optoelectronic devices with greater performance. As such, the utilization of ion‐migration‐produced polarization potential may represent an important endeavor toward a wide range of high‐performance perovskite‐based photodetectors, solar cells, transistors, scintillators, etc.