High‐efficiency electromagnetic (EM) functional materials are the core building block of high‐performance EM absorbers and devices, and they are indispensable in various fields ranging from ...industrial manufacture to daily life, or even from national defense security to space exploration. Searching for high‐efficiency EM functional materials and realizing high‐performance EM devices remain great challenges. Herein, a simple solution‐process is developed to rapidly grow gram‐scale organic–inorganic (MAPbX3, X = Cl, Br, I) perovskite microcrystals. They exhibit excellent EM response in multi bands covering microwaves, visible light, and X‐rays. Among them, outstanding microwave absorption performance with multiple absorption bands can be achieved, and their intrinsic EM properties can be tuned by adjusting polar group. An ultra‐wideband bandpass filter with high suppression level of −71.8 dB in the stopband in the GHz band, self‐powered photodetectors with tunable broadband or narrowband photoresponse in the visible‐light band, and a self‐powered X‐ray detector with high sensitivity of 3560 µC Gyair−1 cm−2 in the X‐ray band are designed and realized by precisely regulating the physical features of perovskite and designing a novel planar device structure. These findings open a door toward developing high‐efficiency EM functional materials for realizing high‐performance EM absorbers and devices.
A facile one‐step solution processing method is developed to rapidly prepare gram‐scale MAPbX3 microcrystals. Utilizing its intrinsic electromagnetic (EM) properties, a series of EM devices is designed and fabricated, which can be applied in the fields of ultra‐wideband bandpass filters and multi‐band photodetection covering X‐rays, UV, visible light, and microwaves.
Hydrogen evolution reaction (HER) is a key step for electrochemical energy conversion and storage. Developing well defined nanostructures as noble‐metal‐free electrocatalysts for HER is promising for ...the application of hydrogen technology. Herein, it is reported that 3D porous hierarchical CoNiP/CoxP multi‐phase heterostructure on Ni foam via an electrodeposition method followed by phosphorization exhibits ultra‐highly catalytic activity for HER. The optimized CoNiP/CoxP multi‐phase heterostructure achieves an excellent HER performance with an ultralow overpotential of 36 mV at 10 mA cm−2, superior to commercial Pt/C. Importantly, the multi‐phase heterostructure shows exceptional stability as confirmed by the long‐term potential cycles (30,000 cycles) and extended electrocatalysis (up to 500 h) in alkaline solution and natural seawater. Experimental characterizations and DFT calculations demonstrate that the strong electronic interaction at the heterointerface of CoNiP/CoP is achieved via the electron transfer from CoNiP to the heterointerface, which directly promotes the dissociation of water at heterointerface and desorption of hydrogen on CoNiP. These findings may provide deep understanding on the HER mechanism of heterostructure electrocatalysts and guidance on the design of earth‐abundant, cost‐effective electrocatalysts with superior HER activity for practical applications.
The CoNiP/CoxP multi‐phase heterostructure with 3D porous hierarchical morphology optimizes the electronic structure, thereby reducing the energy barrier for water dissociation, increasing the adsorption energy of H2O and OH−, and achieving near‐zero Gibbs free energy of hydrogen adsorption. A novel HER mechanism on CoNiP/CoxP multi‐phase heterostructure is proposed to be the water dissociation on heterointerface and H2 production on CoNiP.
Colloidal all‐inorganic perovskites nanocrystals (NCs) have emerged as a promising material for display and lighting due to their excellent optical properties. However, blue emissive NCs usually ...suffer from low photoluminescence quantum yields (PLQYs) and poor stability, rendering them the bottleneck for full‐color all‐perovskite optoelectronic applications. Herein, a facile approach is reported to enhance the emission efficiency and stability of blue emissive perovskite nano‐structures via surface passivation with potassium bromide. By adding potassium oleate and excess PbBr2 to the perovskite precursor solutions, potassium bromide‐passivated (KBr‐passivated) blue‐emitting (≈450 nm) CsPbBr3 nanoplatelets (NPLs) is successfully synthesized with a respectably high PLQY of 87%. In sharp contrast to most reported perovskite NPLs, no shifting in emission wavelength is observed in these passivated NPLs even after prolonged exposures to intense irradiations and elevated temperature, clearly revealing their excellent photo‐ and thermal‐stabilities. The enhancements are attributed to the formation of K‐Br bonding on the surface which suppresses ion migration and formation of Br‐vacancies, thus improving both the PL emission and stability of CsPbBr3 NPLs. Furthermore, all‐perovskite white light‐emitting diodes (WLEDs) are successfully constructed, suggesting that the proposed KBr‐passivated strategy can promote the development of the perovskite family for a wider range of optoelectronic applications.
High‐quality blue‐emitting CsPbBr3 nanoplatelets (NPLs) are synthesized via a facile potassium bromide‐enriched surface passivation. The resultant blue‐emitting (≈450 nm) CsPbBr3 NPLs show a high PLQY of 87% with excellent thermal stability and photostability. Furthermore, white light LEDs based on the mixture perovskite materials including the blue‐emitting NPLs are constructed, demonstrating a wide color gamut.
Stacked 2D perovskites provide more possibilities for next generation photodetector with more new features. Compared with its excellent optoelectronic properties, the good dielectric performance of ...metal halide perovskite rarely comes into notice. Here, a bifunctional perovskite based photovoltaic detector capable of two wavelength demultiplexing is demonstrated. In the Black Phosphorus/Perovskite/MoS2 structured photodetector, the comprehensive utilization of the photosensitive and dielectric properties of 2D perovskite allows the device to work in different modes. The device shows normal continuous photoresponse under 405 nm, while it shows a transient spike response to visible light with longer wavelengths. The linear dynamic range, rise/decay time, and self‐powered responsivity under 405 nm can reach 100, 38 µs/50 µs, and 17.7 mA W‐1, respectively. It is demonstrated that the transient spike photocurrent with long wavelength exposure is related to the illumination intensity and can coexist with normal photoresponse. Two waveband‐dependent signals can be identified and used to reflect more information simultaneously. This work provides a new strategy for multispectral detection and demultiplexing, which can be used to improve data transfer rates and encrypted communications. This work mode can inspire more multispectral photodetectors with different stacked 2D materials, especially to the optoelectronic application of the wide bandgap, high dielectric photosensitive materials.
By employing the photosensitive dielectric property of 2D perovskite, this work provided a demonstration of a bi‐functional photovoltaic detector. A normal response of 405‐nm light and a spike response of long wavelength coexist in this device. The spike response is a result of the dielectric property of 2D perovskite and can be used for two‐wavelength demultiplexing.
For potential applications in ferroelectric switching and piezoelectric nano-generator devices, the promising ferroelectric properties of two dimensional (2D) layered In2Se3 attracted much attention. ...In the present study, 2D In2Se3 flakes down to monolayers are grown by the chemical vapor deposition (CVD) technique on a mica substrate with their structural, optical and ferroelectric properties being studied. The effect of growth parameters (time of growth and Ar flow rate) on the shape and size of the deposited flakes was studied. The optical microscopy study revealed that the flake changed from a circular shape to a sharp face triangle as the Ar flow rate and growth time increased. Raman spectroscopy and high-resolution scanning transmission electron microscopy (HR-STEM) studies revealed that the flakes were of α and β phases, each of which has a hexagonal crystal structure. Strong second harmonic generation (SHG) was observed from α-In2Se3, demonstrating its non-centrosymmetric structure. The piezo-force microscopic (PFM) study showed the presence of out of plane (OOP) ferroelectricity with no in plane (IP) ferroelectricity in CVD grown α-In2Se3 indicating its vertically confined piezoresponse, which was tuned by the applied electric bias and the flake thickness. The present result of shape-controlled growth of In2Se3 with OOP ferroelectricity would open new pathways in the field of 2D ferroelectric switching devices.
Filter‐free color imaging is the long‐pursued solution for its simple structure, low cost, and high stability. However, a spectroscopic unit is still necessary for the current Si‐based imaging unit ...due to the intrinsic photoresponse properties of Si. Here, the authors demonstrate a filter‐free color‐resolved single‐pixel imaging (SPI) by combining the working mechanism of computational ghost imaging and the response characteristic of perovskite. Benefitting from a broad linear dynamic range (106.5 dB) and a high detectivity (4.03 × 1014 Jones) of the fabricated ultrasensitive MAPbBr3 microwire arrays (MWAs) photodetector, the light attenuation caused by an object can be effectively correlated with its color. The reconstructed images of both transmissive and reflective color objects show a high wavelength resolution reaching 20 nm in the range of 400–540 nm, which is impossible to achieve by commercial silicon‐photodiode‐based ones. This work can open a new door for the image acquisition of color‐sensitive objects and also pave a way for the evolution of the next generation of detectors and cameras with low‐dimensional perovskite materials.
The overall performance of MAPbBr3 microwire arrays photodetector is used to implement a filter‐free color single‐pixel imaging system. The reconstructed images of both transmissive and reflective wavelength‐modulated colored objects show a high wavelength resolution of up to 20 nm in the range of 400–540 nm, which is impossible to achieve by commercial silicon‐photodiode‐based ones.
Abstract
Highly efficient multi-dimensional data storage and extraction are two primary ends for the design and fabrication of emerging optical materials. Although metasurfaces show great potential ...in information storage due to their modulation for different degrees of freedom of light, a compact and efficient detector for relevant multi-dimensional data retrieval is still a challenge, especially in complex environments. Here, we demonstrate a multi-dimensional image storage and retrieval process by using a dual-color metasurface and a double-layer integrated perovskite single-pixel detector (DIP-SPD). Benefitting from the photoelectric response characteristics of the FAPbBr
2.4
I
0.6
and FAPbI
3
films and their stacked structure, our filter-free DIP-SPD can accurately reconstruct different colorful images stored in a metasurface within a single-round measurement, even in complex environments with scattering media or strong background noise. Our work not only provides a compact, filter-free, and noise-robust detector for colorful image extraction in a metasurface, but also paves the way for color imaging application of perovskite-like bandgap tunable materials.
CsPbBr3 nanoplates (NPs) have shown great potential in diverse optoelectronic applications. Despite the wonderful luminescence properties, the inherent instability of these NPs hinders their use in ...practical situations. Herein, a facile water‐assisted strategy is reported to synthesize highly stable blue emission CsPbBr3 NPs encapsulated in PbBr(OH). The introduction of water directly into the reaction mixture is pivotal, as it triggers the transformation of bulk CsPbBr3 nanocubes into 2‐D CsPbBr3 NPs within the PbBr(OH) matrix, resulting in the formation of CsPbBr3@PbBr(OH) microbricks. Remarkably, the water content in the reaction mixture allows the control of the number of perovskite layers in the NPs, thus enabling the emission color to be tuned from deep blue to green. The unconventional approach presented herein not only offers a cost‐effective pathway to synthesize blue‐emitting perovskites which are highly stable in a wide variety of polar and non‐polar solvents, but also holds immense potential for propelling the advancement of high‐performance LEDs and other optoelectronic devices. The findings underscore the significance of water in dictating the growth dynamics and emission characteristics of perovskite NPs, paving the way for their practical application.
Water slowly dissolves the CsPbBr3 nanocrystals and creates a Cs‐deficit environment for the subsequent growth of blue‐emitting CsPbBr3 NPs, which are eventually embedded inside a large PbBr(OH) matrix. This 3‐step process effectively favors the formation of NPs in which the number of layers and the emission wavelength can be manipulated with the water content.
Self-powered, highly spectrum-selective photodetectors have been fabricated from n-ZnO/p-NiO core-shell nanowire arrays. In the structure, the outer-layer of the p-NiO acts as a "filter" which can ...filter out the photons with short wavelength. In this way, highly spectrum-selective photodetectors that only respond to a narrow spectrum range have been obtained.
