Metal halide perovskites (MHPs) have been a hot research topic due to their facile synthesis, excellent optical and optoelectronic properties, and record‐breaking efficiency of corresponding optoelectronic devices. Nowadays, the development of miniaturized high‐performance photodetectors (PDs) has been fueling the demand for novel photoactive materials, among which low‐dimensional MHPs have attracted burgeoning research interest. In this report, the synthesis, properties, photodetection performance, and stability of low‐dimensional MHPs, including 0D, 1D, 2D layered and nonlayered nanostructures, as well as their heterostructures are reviewed. Recent advances in the synthesis approaches of low‐dimensional MHPs are summarized and the key concepts for understanding the optical and optoelectronic properties related to the PD applications of low‐dimensional MHPs are introduced. More importantly, recent progress in novel PDs based on low‐dimensional MHPs is presented, and strategies for improving the performance and stability of perovskite PDs are highlighted. By discussing recent advances, strategies, and existing challenges, this progress report provides perspectives on low‐dimensional MHP‐based PDs in the future.
China’s population has rapidly aged over the recent decades of social and economic development as neurodegenerative disorders have proliferated, especially Alzheimer’s disease (AD) and related dementias (ADRD). AD’s incidence rate, morbidity, and mortality have steadily increased to make it presently the fifth leading cause of death among urban and rural residents in China and magnify the resulting financial burdens on individuals, families and society. The ‘Healthy China Action’ plan of 2019–2030 promotes the transition from disease treatment to health maintenance for this expanding population with ADRD. This report describes related epidemiological trends, evaluates the economic burden of the disease, outlines current clinical diagnosis and treatment status and delineates existing available public health resources. More specifically, it examines the public health impact of ADRD, including prevalence, mortality, costs, usage of care, and the overall effect on caregivers and society. In addition, this special report presents technical guidance and supports for the prevention and treatment of AD, provides expertise to guide relevant governmental healthcare policy development and suggests an information platform for international exchange and cooperation.
higher carrier mobility and longer carrier lifetime, thanks to their fewer grain boundaries, enhanced crystallinity and reduced trap density. With such performance improvements, the lead-free halide perovskite single crystal is considered to be a promising photosensitive material in optoelectronic devices. [6] In order to effectively promote power conversion efficiency, the thickness of leadfree halide perovskite single crystal should be controlled at a suitable level, which is suggested to be greater than light-absorption length and less than carrier-diffusion length. [7] In the current semiconductor and photoelectronic industries, thin silicon wafers are fabricated mainly through top-down process, which requires high yields accompanied with large material loss, waste and subsequent complicated slicing process. Against this background, a facile and effective space-confined fabrication is adopted to produce large singlecrystalline thin film, through a bottom-up process. [8] Compared with vapor epitaxial growth and cavitation triggered asymmetrical crystallization, [9] space-confined methods possess moderate growth conditions to grow SCTF without rigorous restrictions. However, this method is limited to the growth of organic-inorganic lead halide perovskite SCTF, few studies focus on lead-free halide perovskite SCTF, such as Sn-based, Bi-based and Sb-based, etc. This is limited by the lack of understanding of the precursor solution chemistry in space-confined method. [10] Although previous work pointed out that the preheated-substrate and local heating are important in the space-confined growth, [11] there is a lack of investigation on the influence of the precursor solution temperature on the crystallization process. In general, the growth drive force of the space-confined growth is considered to be inverse-temperature crystallization or solvent evaporation, in which the supersaturation plays a key role in controlling size and quality. [12] An indepth insight of the relationship between the nucleation and crystallization process in the precursor solution is of significant importance. Therefore, it is necessary to clarify the effects of supersaturation in the space-confined growth.Furthermore, the space-confined method demonstrates the advantage of substrate-independent characteristics, which facilitate convenient integration of lead-free halide perovskite SCTF Monolithical integration of the promising optoelectronic material with mature and inexpensive silicon circuitry contributes to simplifying device geometry, enhancing performance, and expanding new functionalities. Herein, a leadfree halide perovskite Cs 3 Bi 2 I 9 single-crystalline thin film (SCTF), with thickness ranging from 900 nm to 4.1 µm and aspect ratio up to 1666, is directly integrated on various substrates including Si wafer, through a facile and lowtemperature solution-processing method. The growth kinetics of the lead-free halide perovskite SCTF are elucidated by in situ observation, and the solution supersaturation is controlled to reduce the ...
We first report two-dimensional (2D) perovskite Ca 2 Nb 3 O 10 ultraviolet photodetectors (UV PDs), which are prepared via a facile calcination-exfoliation method. The 2D Ca 2 Nb 3 O 10 PDs demonstrate high performance at 3 V at 280 nm, high responsivity (14.94 A W −1 ), high detectivity (8.7 × 10 13 Jones), high spectral selectivity (R 280 /R 400 = 8.84 × 10 3 ), fast speed (0.08/5.6 ms), and long-term stability, exceeding those of most reported UV PDs. Furthermore, the Ca 2 Nb 3 O 10 PDs integrated with poly(ethylene terephthalate) (PET) show excellent flexibility and have high linear dynamic range (96 dB). Our work provides a general strategy for searching new UV PDs based on numerous layered niobates. The Ca 2 Nb 3 O 10 nanosheets may be one of the optimum semiconductor materials for next-generation high-performance UV PDs.
Tunable work function has a high profile for the MXene-based optoelectronic devices, and surface modification provides the huge potential to shift its Fermi level and modulate the work function. In this work, the window of MXene's work function is engineered from 4.55 to 5.25 eV by surface modification with LiF, Se, and polyethylenimine ethoxylated (PEIE). The vertical p-CsCu 2 I 3 /n-Ca 2 Nb 3-x Ta x O 10 junction photodetectors are constructed on the basis of the above surfacemodified MXenes, which changes the Schottky barrier between n-Ca 2 Nb 3-x Ta x O 10 and the electrodes. In particular, the rectification effect is significantly enhanced by utilizing PEIE-decorated MXene electrodes, resulting in a high rectification ratio of 16 136 and improved UV responsivity of 81.3 A W -1 . Such high-performance devices based on MXenes electrodes are compatible with the standard clean room fabrication process, realizing large-scale flexible UV detectors that maintain 80% of the original current after 5000 times bending. Meanwhile, a photodetector array stimulated with UV of different wavelengths is constructed to reveal its potential for image sensing. Finally, functional "AND" and "OR" optoelectronic logic gates are developed for UV communication using Au/ CsCu 2 I 3 /Ca 2 Nb 3-x Ta x O 10 /MXene-PEIE photodetectors, enriching the application of MXene-based optoelectronic devices. This work on tuning MXene work function via surface modification demonstrates that MXene is a promising candidate for future optoelectronics.
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