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Driven by the Internet of Everything, one of the main goals in human–computer interaction is to achieve intuitive, effortless, and easy‐to‐learn communication. Thus, senseless optoelectronic devices with high response performance under ambient environment have an extensive application space in improving the interfacing between users and computers. Herein, a concept of wearable perovskite‐based shadow recognition sensor is demonstrated for ambient and nonobtrusive human–computer interaction. The multidimensional ordered nucleation and growth of perovskite crystals are promoted by introducing the self‐driving effect of liquid crystal (LC) oligomers. The resulted LC‐doped perovskite film (LC‐PVK) with micrometer‐sized grains can output relatively high photocurrent under indoor ambient light (≈500 lux). The LC‐based device exhibits over a hundred times of on–off ratio and fast response of millisecond level even after storage for more than 1200 h. The device also shows an ultratrace Pb2+ leakage of 1.02 μg L−1 in water, and still retains more than 90% of the photocurrent intensity after thousands of bending strains. Accordingly, a novel human–computer interaction is achieved by identifying external action commands with the recognition of shadows, which can provide a "haptic" perception for robots. [ABSTRACT FROM AUTHOR]

Inorganic cesium lead iodide perovskite CsPbI3 is attracting great attention as a light absorber for single or multi‐junction photovoltaics due to its outstanding thermal stability and proper band gap. However, the device performance of CsPbI3‐based perovskite solar cells (PSCs) is limited by the unsatisfactory crystal quality and thus severe non‐radiative recombination. Here, vacuum‐assisted thermal annealing (VATA) is demonstrated as an effective approach for controlling the morphology and crystallinity of the CsPbI3 perovskite films formed from the precursors of PbI2, CsI, and dimethylammonium iodide (DMAI). By this method, a large‐area and high‐quality CsPbI3 film is obtained, exhibiting a much reduced trap‐state density with prolonged charge lifetime. Consequently, the solar cell efficiency is raised from 17.26 to 20.06 %, along with enhanced stability. The VATA would be an effective approach for fabricating high‐performance thin‐film CsPbI3 perovskite optoelectronics. [ABSTRACT FROM AUTHOR]

2D‐material‐based membranes with densely packed sub‐nanometer‐height fluidic channels show exceptional transport properties, and have attracted broad research interest for energy‐, environment‐, and healthcare‐related applications. Recently, light‐controlled active transport of ionic species in abiotic materials have received renewed attention. However, its dependence on inhomogeneous or site‐specific illumination is a challenge for scalable application. Here, directional proton transport through printed asymmetric graphene oxide superstructures (GOSs) is demonstrated under full‐area illumination. The GOSs are composed of partially stacked graphene oxide multilayers formed by a two‐step direct ink writing process. The direction of the photoinduced proton current is determined by the position of top graphene oxide multilayers, which functions as a photogate to modulate the horizontal ion transport through the beneath lamellar nanochannels. This transport phenomenon unveils a new driving mechanism that, in asymmetric nanofluidic structures, the decay of local light intensity in depth direction breaks the balance of electric potential distribution in horizontal direction, and thus generates a photoelectric driving force for ion transport. Following this mechanism, the GOSs are developed into photonic ion transistors with three different gating modes. The asymmetrically printed photonic‐ionic devices provide fundamental elements for light‐harvesting nanofluidic circuits, and may find applications for artificial photosynthesis and artificial electric organs. [ABSTRACT FROM AUTHOR]

Flexible wearable sensors are expected to be the future generation of personal health monitoring devices with large‐area, multimodal, multipoint sensing, and complicated data analysis. However, multimaterial interfacial coalescence and mechanical matching critically challenge the advancement of flexible devices and multifunction integration. Graphene, with characteristic carbon sheet 2D material, is endowed with good transparency, stability, superior electron mobility, heat conductivity, excellent flexibility, and mechanical performance. A summary of the progresses of flexible graphene‐based sensors in terms of material processing, sensor configuration, and property is presented. Various assembly structures could perform different electrical behaviors with unitary graphene material. The diversity of graphene‐based temperature, humidity, pressure, strain, and integrated multifunctional sensors developed in recent years is detailed. Benefitting from the commendable flexible mechanical performance and high durability, flexible graphene‐based sensors promote practical applications in body temperature monitoring, voice recognition, pulse‐beating, motion, and respiration detection. Finally, future research following the development trends and challenges of integrated graphene‐based sensors to develop their potential in human health monitoring and human–machine interfaces are discussed. The progresses of flexible graphene‐based temperature, humidity, pressure, strain, and integrated multifunctional sensors in terms of material processing, sensor configuration and properties are summarized. Benefitting with the flexible mechanical performance and high durability, graphene‐based sensors promote practical applications in temperature monitoring, voice recognition, pulse beating, motion, and respiration detection. The development trends and challenges on their commercialization are also discussed. [ABSTRACT FROM AUTHOR]

All-inorganic cesium lead triiodide (CsPbI 3 ) perovskite has received increasing attention due to its intrinsic thermal stability and suitable band gap for photovoltaic applications. However, it is difficult to deposit high-quality pure-phase CsPbI 3 films using CsI and PbI 2 as precursors due to the rapid nucleation and crystal growth by the solution coating method. Here, a simple cation-exchange approach is employed to fabricate all-inorganic 3D CsPbI 3 perovskite, where 1D ethylammonium lead (EAPbI 3 ) perovskite is first solution-deposited and then transformed to 3D CsPbI 3 via ion exchange between EA + and Cs + during thermal annealing. The large space between the PbI 3 - skeletons in 1D EAPbI 3 favors the cation interdiffusion and exchange for the formation of pure-phase 3D CsPbI 3 with full compactness and high crystallinity and orientation. The resulting CsPbI 3 film exhibits a low trap density of state and high charge mobility, and the perovskite solar cell shows a power-conversion efficiency of 18.2% with enhanced stability. This strategy provides an alternative and promising fabrication route for the fabrication of high-quality all-inorganic perovskite devices.

Inorganic cesium lead iodide perovskite CsPbI 3 is attracting great attention as a light absorber for single or multi-junction photovoltaics due to its outstanding thermal stability and proper band gap. However, the device performance of CsPbI 3 -based perovskite solar cells (PSCs) is limited by the unsatisfactory crystal quality and thus severe non-radiative recombination. Here, vacuum-assisted thermal annealing (VATA) is demonstrated as an effective approach for controlling the morphology and crystallinity of the CsPbI 3 perovskite films formed from the precursors of PbI 2 , CsI, and dimethylammonium iodide (DMAI). By this method, a large-area and high-quality CsPbI 3 film is obtained, exhibiting a much reduced trap-state density with prolonged charge lifetime. Consequently, the solar cell efficiency is raised from 17.26 to 20.06 %, along with enhanced stability. The VATA would be an effective approach for fabricating high-performance thin-film CsPbI 3 perovskite optoelectronics., (© 2022 Wiley-VCH GmbH.)

Novel all-inorganic Sn-Pb alloyed perovskites are developed aiming for low toxicity, low bandgap, and long-term stability. Among them, CsPb 1- x Sn x I 2 Br is predicted as an ideal perovskite with favorable band gap, but previously is demonstrated unable to convert to perovskite phase by thermal annealing. In this report, a series of CsPb 1- x Sn x I 2 Br perovskites with tunable bandgaps from 1.92 to 1.38 eV are successfully prepared for the first time via low annealing temperature (60 °C). Compared to the pure CsPbI 2 Br, these Sn-Pb alloyed perovskites show superior stability. Furthermore, a novel α-phase-stabilization mechanism of the inorganic Sn-Pb alloyed perovskite by reconfiguring the perovskite crystallization process with chloride doping is provided. Simultaneously, a dense protection layer is formed by the coordination reaction between the surface lead dangling bonds and sulfate ion to retard the permeation of external oxygen and moisture, leading to less oxidation of Sn 2+ in perovskite film. As a result, the fabricated all-inorganic Sn-Pb perovskite solar cells (PSCs) show a champion power conversion efficiency of 10.39% with improved phase stability and long-term ambient stability against light, heat, and humidity. This work provides a viable strategy in fabricating high-performance narrow-bandgap all-inorganic PSCs., (© 2021 Wiley-VCH GmbH.)