Nowadays, great effort has been devoted to establishing wearable electronics with excellent stretchability, high sensitivity, good mechanical strength, and multifunctional characteristics. Herein, a soft conductive hydrogel is rationally designed by proportionally mixing silk fibroin, polyacrylamide, graphene oxide, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate). The resultant hydrogel has considerable stretchability and compressibility, which enables it to be assembled into a strain/pressure sensor with a wide sensing range (strain, 2%-600%; pressure, 0.5-119.4 kPa) and reliable stability. Then, the corresponding sensor is capable of monitoring a series of physical signals of the human body (e.g., joint movement, facial gesture, pulse, breathing, etc.). In particular, the hydrogel-based sensor is biocompatible, with no anaphylactic reaction on human skin. More interestingly, this conductive hydrogel exhibits a positive response when it works in a triboelectric nanogenerator; consequently, it lights up 20 commericial green light-emitting diodes. Thus, this silk fibroin-based hydrogel is a kind of multifunctional material toward wearable electronics with versatile applications in health and exercise monitors, soft robots, and power sources.

Stretchable, Biocompatible, and Multifunctional Silk Fibroin-Based Hydrogels toward Wearable Strain/Pressure Sensors and Triboelectric Nanogenerators.

Low trap-state density, high carrier mobility, and efficient charge carrier collection are key parameters for photodetectors with high sensitivity and fast response time. This study demonstrates a simple solution growth method to prepare CsPbBr3 microcrystals (MCs) with low trap-state density. Time-dependent photoluminescence study with one-photon excitation (OPE) and two-photon excitation (TPE) indicates that CsPbBr3 MCs exhibit fast carrier diffusion with carrier mobility over 100 cm2 V-1 S-1 . Furthermore, CsPbBr3 MC-based photodetectors with high charge carriers' collection efficiency are fabricated. Such photodetectors show ultrahigh responsivity (R) up to 6 × 104 A W-1 with OPE and high R up to 6 A W-1 with TPE. The R for OPE is over one order of magnitude higher (the R for TPE is three orders of magnitude higher) than that of previously reported all-inorganic perovskite-based photodetectors. Moreover, the photodetectors exhibit fast response time of ≈1 ms, which corresponds to a gain ≈105 and a gain- bandwidth product of 108 Hz for OPE (a gain ≈103 and a gain-bandwidth product of 106 Hz for TPE).

Ultrasensitive and Fast All‐Inorganic Perovskite‐Based Photodetector via Fast Carrier Diffusion

Within a few lines, a simple dynamic model of the universe can be constructed that is offering a life environment to modules and modular systems.

A Simple Model

The in-depth understanding of ions' generation and movement inside all-inorganic perovskite quantum dots (CsPbBr3 QDs), which may lead to a paradigm to break through the conventional von Neumann bottleneck, is strictly limited. Here, it is shown that formation and annihilation of metal conductive filaments and Br- ion vacancy filaments driven by an external electric field and light irradiation can lead to pronounced resistive-switching effects. Verified by field-emission scanning electron microscopy as well as energy-dispersive X-ray spectroscopy analysis, the resistive switching behavior of CsPbBr3 QD-based photonic resistive random-access memory (RRAM) is initiated by the electrochemical metallization and valance change. By coupling CsPbBr3 QD-based RRAM with a p-channel transistor, the novel application of an RRAM-gate field-effect transistor presenting analogous functions of flash memory is further demonstrated. These results may accelerate the technological deployment of all-inorganic perovskite QD-based photonic resistive memory for successful logic application.

Synergies of Electrochemical Metallization and Valance Change in All-Inorganic Perovskite Quantum Dots for Resistive Switching

Band gap tunable hybrid organic–inorganic lead halide perovskites (APbX3, A = CH3NH3+ and NH2CH═NH2+, and X = Cl, Br, or I) have attracted significant attention in optoelectronic- and photovoltaic-related fields on account of their outstanding optoelectronic properties. Single crystals of hybrid perovskites, such as CH3NH3PbI3 and CH3NH3PbBr3, were certified to be advantageous over thin films as photodetectors. However, their resistance toward heat and moisture hinders their future development. Fully inorganic perovskite CsPbBr3 stands a chance to fill the gap as a novel photodetector with perovskite structure. We revealed the growth of CsPbBr3 single crystal was of a 2D nucleation mechanism. Similarities of d values and octahedra arrangements along [101] and [020] orientations restricted single-crystal growth. Under optimized conditions, orthorhombic CsPbBr3 single crystals with (101) crystallographic facets were grown by using methyl alcohol as antisolvent from saturated DMSO solution. The optoelectroni...

High Detectivity and Rapid Response in Perovskite CsPbBr3 Single-Crystal Photodetector

All-inorganic perovskite CsPbX3 (X = Cl, Br, or I) is widely used in a variety of photoelectric devices such as solar cells, light-emitting diodes, lasers, and photodetectors. However, studies to understand the flexible CsPbX3 electrical application are relatively scarce, mainly due to the limitations of the low-temperature fabricating process. In this study, all-inorganic perovskite CsPbBr3 films were successfully fabricated at 75 °C through a two-step method. The highly crystallized films were first employed as a resistive switching layer in the Al/CsPbBr3/PEDOT:PSS/ITO/PET structure for flexible nonvolatile memory application. The resistive switching operations and endurance performance demonstrated the as-prepared flexible resistive random access memory devices possess reproducible and reliable memory characteristics. Electrical reliability and mechanical stability of the nonvolatile device were further tested by the robust current–voltage curves under different bending angles and consecutive flexing ...

Flexible All-Inorganic Perovskite CsPbBr3 Nonvolatile Memory Device

Halide perovskite nanomaterials have recently attracted a lot of attention in the nanoscale laser research field, especially two-photon pumped lasing in halide perovskite nanomaterials has been considered as an ideal alternative strategy to achieve frequency upconversion. However, the poor stability of current organic–inorganic lead halide perovskite materials hinder their further practical applications. Herein, facile solution-processed cesium lead halide perovskite CsPbX3 (X = Br, I, or Cl) microcubes with low-threshold lasing, high quality, enhanced stability, and excellent wavelength tunability are reported. These as-prepared CsPbX3 microcubes display excellent structure stability under ambient conditions for several months and they are found to be more robust than their organic–inorganic counterparts. The smooth end facets and wavelength-comparable dimensions make these microcubes promising for high-quality laser cavities in three dimensions. Fabry–Perot lasing is demonstrated in CsPbX3 microcubes, the process of which is investigated by dynamic emission. In addition, tunable amplified spontaneous emission is achieved with low threshold under both one- and two-photon excitation, which can maintain a stable emission for over 10 hours under continuous intense laser shots in ambient atmosphere. The findings suggest that solution-processed all-inorganic perovskite microcubes can be used as excellent gain medium for frequency upconversion lasers, which would offer a new platform for nonlinear photoelectric devices.

Robust Cesium Lead Halide Perovskite Microcubes for Frequency Upconversion Lasing

Two-step method for preparing all-inorganic CsPbBr3 perovskite film and its photoelectric detection application

Nonlocality Induced Cherenkov Threshold

With the rapid developments in compact devices, the multi-function and reconfigurability of nanostructures are highly appreciated, while still very challenging. A majority of devices are usually mono-functional or hard to switch between different functions in one design. In this paper, we proposed graphene-wrapped core-shell nanowires to realize real-time reconfigurable sensors and nanoantenna by tuning the Fermi energies of graphene layers at the surfaces of core and shell, respectively. Owing to the electromagnetic coupling between the two graphene layer, two corresponding Fano resonances of scattering can arise in the Terahertz spectrum, which arises from the interference of bright modes and dark modes. Around the Fano resonances, the scattering can be considerably resonant (as an antenna) or suppressed (as a sensor). Interestingly, the field distributions are distinct at the suppressed scattering states for the two Fano resonances. The presented reconfigurable nanostructures may offer promising potentials for integrated and multi-functional electromagnetic control such as dynamic sensing and emission.

Dongjue Liu

Papers

Flexible All-Inorganic Perovskite CsPbBr3 Nonvolatile Memory Device

Robust Cesium Lead Halide Perovskite Microcubes for Frequency Upconversion Lasing

Two-step method for preparing all-inorganic CsPbBr3 perovskite film and its photoelectric detection application

Nonlocality Induced Cherenkov Threshold

Reconfigurable sensor and nanoantenna by graphene-tuned Fano resonance.