Wuyi University

Beyond the unprecedented success achieved in photovoltaics (PVs), lead halide perovskites (LHPs) have shown great potential in other optoelectronic devices. Among them, nanometer-scale perovskite quantum dots (PQDs) with fascinating optical properties including high brightness, tunable emission wavelength, high color purity, and high defect tolerance have been regarded as promising alternative down-conversion materials in phosphor-converted light-emitting diodes (pc-LEDs) for lighting and next-generation of display technology. Despite the promising applications of perovskite materials in various fields, they have received strong criticism for the lack of stability. The poor stability has also attracted much attention. Within a few years, numerous strategies towards enhancing the stability have been developed. This review summarizes the mechanisms of intrinsic- and extrinsic-environment-induced decomposition of PQDs. Simultaneously, the strategies for improving the stability of PQDs are reviewed in detail, which can be classified into four types: (1) compositional engineering; (2) surface engineering; (3) matrix encapsulation; (4) device encapsulation. Finally, the challenges for applying PQDs in pc-LEDs are highlighted, and some possible solutions to improve the stability of PQDs together with suggestions for further improving the performance of pc-LEDs as well as the device lifetime are provided.

Abstract The current boom of safe and renewable energy storage systems is driving the recent renaissance of Zn‐ion batteries. However, the notorious tip‐induced dendrite growth on the Zn anode restricts their further application. Herein, the first demonstration of constructing a flexible 3D carbon nanotube (CNT) framework as a Zn plating/stripping scaffold is constituted to achieve a dendrite‐free robust Zn anode. Compared with the pristine deposited Zn electrode, the as‐fabricated Zn/CNT anode affords lower Zn nucleation overpotential and more homogeneously distributed electric field, thus being more favorable for highly reversible Zn plating/stripping with satisfactory Coulombic efficiency rather than the formation of Zn dendrites or other byproducts. As a consequence, a highly flexible symmetric cell based on the Zn/CNT anode presents appreciably low voltage hysteresis (27 mV) and superior cycling stability (200 h) with dendrite‐free morphology at 2 mA cm −2 , accompanied by a high depth of discharge (DOD) of 28%. Such distinct performance overmatches most of recently reported Zn‐based anodes. Additionally, this efficient rechargeability of the Zn/CNT anode also enables a substantially stable Zn//MnO 2 battery with 88.7% capacity retention after 1000 cycles and remarkable mechanical flexibility.

Abstract A self‐powered, high‐performance Ti 3 C 2 T x MXene/GaN van der Waals heterojunction (vdWH)‐based ultraviolet (UV) photodiode is reported. Such integration creates a Schottky junction depth that is larger than the UV absorption depth to sufficiently separate the photoinduced electron/hole pairs, boosting the peak internal quantum efficiency over the unity and the external quantum efficiency over 99% under weak UV light without bias. The proposed Ti 3 C 2 T x /GaN vdWH UV photodiode demonstrates pronounced photoelectric performances working in self‐powered mode, including a large responsivity (284 mA W −1 ), a high specific detectivity (7.06 × 10 13 Jones), and fast response speed (rise/decay time of 7.55 µs/1.67 ms). Furthermore, the remarkable photovoltaic behavior leads to an impressive power conversion efficiency of 7.33% under 355 nm UV light illumination. Additionally, this work presents an easy‐processing spray‐deposition route for the fabrication of large‐area UV photodiode arrays that exhibit highly uniform cell‐to‐cell performance. The MXene/GaN photodiode arrays with high‐efficiency and self‐powered ability show high potential for many applications, such as energy‐saving communication, imaging, and sensing networks.

Abstract Red phosphor materials play a key role in improving the lighting and backlit display quality of phosphor-converted white light-emitting diodes (pc-WLEDs). However, the development of a red phosphor with simultaneous high efficiency, excellent thermal stability and high colour purity is still a challenge. In this work, unique non-concentration quenching in solid-solution Cs 3 Gd 1 − x Ge 3 O 9 : x Eu 3+ (CGGO: x Eu 3+ ) ( x = 0.1–1.0) phosphors is successfully developed to achieve a highly efficient red-emitting Cs 3 EuGe 3 O 9 (CEGO) phosphor. Under the optimal 464 nm blue light excitation, CEGO shows a strong red emission at 611 nm with a high colour purity of 95.07% and a high internal quantum efficiency of 94%. Impressively, this red-emitting CEGO phosphor exhibits a better thermal stability at higher temperatures (175–250 °C, >90%) than typical red K 2 SiF 6 :Mn 4+ and Y 2 O 3 :Eu 3+ phosphors, and has a remarkable volumetric negative thermal expansion (coefficient of thermal expansion, α = −5.06 × 10 −5 /°C, 25–250 °C). By employing this red CEGO phosphor, a fabricated pc-WLED emits warm white light with colour coordinates (0.364, 0.383), a high colour rendering index (CRI = 89.7), and a low colour coordinate temperature (CCT = 4508 K). These results indicate that this highly efficient red-emitting phosphor has great potential as a red component for pc-WLEDs, opening a new perspective for developing new phosphor materials.

Hyperspectral imaging fully portrays materials through numerous and contiguous spectral bands. It is a very useful technique in various fields, including astronomy, medicine, food safety, forensics, and target detection. However, hyperspectral images include redundant measurements, and most classification studies encountered the Hughes phenomenon. Finding a small subset of effective features to model the characteristics of classes represented in the data for classification is a critical preprocessing step required to render a classifier effective in hyperspectral image classification. In our previous work, an automatic method for selecting the radial basis function (RBF) parameter (i.e., σ) for a support vector machine (SVM) was proposed. A criterion that contains the between-class and within-class information was proposed to measure the separability of the feature space with respect to the RBF kernel. Thereafter, the optimal RBF kernel parameter was obtained by optimizing the criterion. This study proposes a kernel-based feature selection method with a criterion that is an integration of the previous work and the linear combination of features. In this new method, two properties can be achieved according to the magnitudes of the coefficients being calculated: the small subset of features and the ranking of features. Experimental results on both one simulated dataset and two hyperspectral images (the Indian Pine Site dataset and the Pavia University dataset) show that the proposed method improves the classification performance of the SVM.

Abstract Perovskite light‐emitting diodes (PeLEDs) have received great attention in recent years due to their narrow emission bandwidth and tunable emission spectrum. Efficient red emission is one of most important parts for lighting and displays. Quasi‐2D perovskites can deliver high emission efficiency due to the strong carrier confinement, while the external quantum efficiencies (EQE) of red quasi‐2D PeLEDs are inefficient at present, which is due to the complex distribution of different n ‐value phases in quasi‐2D perovskite films. In this work, the phase distribution of the quasi‐2D perovskite is finely controlled by mixing two different large organic cations, which effectively reduces the amount of smaller n ‐index phases, meanwhile the passivation of lead and halide defects in perovskite films is realized. Accordingly, the PeLEDs show 25.8% EQE and 1300 cd m −2 maximum brightness at 680 nm, which exhibits the highest performance for red PeLEDs up to now.

Abstract Phosphor-converted white-light-emitting diodes (pc-WLED) have been extensively employed as solid-state lighting sources, which have a very important role in people’s daily lives. However, due to the scarcity of the red component, it is difficult to realize warm white light efficiently. Hence, red-emitting phosphors are urgently required for improving the illumination quality. In this work, we develop a novel orangish-red La 4 GeO 8 :Bi 3+ phosphor, the emission peak of which is located at 600 nm under near-ultraviolet (n-UV) light excitation. The full width at half maximum (fwhm) is 103 nm, the internal quantum efficiency (IQE) exceeds 88%, and the external quantum efficiency (EQE) is 69%. According to Rietveld refinement analysis and density functional theory (DFT) calculations, Bi 3+ ions randomly occupy all La sites in orthorhombic La 4 GeO 8 . Importantly, the oxygen-vacancy-induced electronic localization around the Bi 3+ ions is the main reason for the highly efficient orangish-red luminescence. These results provide a new perspective and insight from the local electron structure for designing inorganic phosphor materials that realize the unique luminescence performance of Bi 3+ ions.

Metal organic frameworks (MOFs), an emerging class of nanoporous crystalline materials, have become increasingly attractive for solar energy applications. In this work, we report a newly designed mixed-node MOF catalyst, CoxFe1–x-MOF-74 (0 < x ≤ 1), which acts as a highly efficient electrocatalyst for oxygen evolution reaction (OER) in alkaline solution with remarkably low overpotential (280 mV at a current density of 10 mA/cm2), small Tafel slope (56 mV/dec), and high faradic efficiency (91%) and can deliver a current density of 20 mA/cm2 at 1.58 V for overall water splitting. Moreover, using the combination of multiple spectroscopic methods, including X-ray absorption, electron spin resonance, and X-ray photoelectron spectroscopy, etc., we unraveled the mechanistic origin of the enhanced catalytic performance of CoxFe1–x-MOF-74 compared to its single-metal counterparts. We show the mixed-node MOF can provide more open metal sites and an enhanced electron-rich environment, which facilitates efficient charge transfer and results in significantly enhanced OER activity.

The voltage of carbon-based aqueous supercapacitors is limited by the water splitting reaction occurring in one electrode, generally resulting in the promising but unused potential range of the other electrode. Exploiting this unused potential range provides the possibility for further boosting their energy density. An efficient surface charge control strategy was developed to remarkably enhance the energy density of multiscale porous carbon (MSPC) based aqueous symmetric supercapacitors (SSCs) by controllably tuning the operating potential range of MSPC electrodes. The operating voltage of the SSCs with neutral electrolyte was significantly expanded from 1.4 V to 1.8 V after simple adjustment, enabling the energy density of the optimized SSCs reached twice as much as the original. Such a facile strategy was also demonstrated for the aqueous SSCs with acidic and alkaline electrolytes, and is believed to bring insight in the design of aqueous supercapacitors.

White organic light-emitting diodes (WOLEDs) are superior to traditional incandescent light bulbs and compact fluorescent lamps in terms of their merits in ensuring pure white-light emission, low-energy consumption, large-area thin-film fabrication, etc. Unfortunately, WOLEDs based on multilayered or multicomponent (red, green, and blue (RGB)) emissive layers can suffer from some remarkable disadvantages, such as intricate device fabrication and voltage-dependent emission color, etc. Single molecules, which can emit white light, can be used to replace multiple emitters, leading to a simplified fabrication process, stable and reproducible WOLEDs. Recently, the performance of WOLEDs by using single molecules is catching up with that of the state-of-the-art devices fabricated by multicomponent emitters. Therefore, an increasing attention has been paid on single white-light-emitting materials for efficient WOLEDs. In this review, different mechanisms of white-light emission from a single molecule and the performance of single-molecule-based WOLEDs are collected and expounded, hoping to light up the interesting subject on single-molecule white-light-emitting materials, which have great potential as white-light emitters for illumination and lighting applications in the world.

Abstract Nowadays, photodynamic therapy (PDT) is under the research spotlight as an appealing modality for various malignant tumors. Compared with conventional PDT treatment activated by ultraviolet or visible light, near infrared (NIR) light‐triggered PDT possessing deeper penetration to lesion area and lower photodamage to normal tissue holds great potential for in vivo deep‐seated tumor. In this review, recent research progress related to the exploration of NIR light responsive PDT nanosystems is summarized. To address current obstacles of PDT treatment and facilitate the effective utilization, several innovative strategies are developed and introduced into PDT nanosystems, including the conjugation with targeted moieties, O 2 self‐sufficient PDT, dual photosensitizers (PSs)‐loaded PDT nanoplatform, and PDT‐involved synergistic therapy. Finally, the potential challenges as well as the prospective for further development are also discussed.

Abstract Perovskite light‐emitting diodes (PeLEDs) are considered as particularly attractive candidates for high‐quality lighting and displays, due to possessing the features of wide gamut and real color expression. However, most PeLEDs are made from polycrystalline perovskite films that contain a high concentration of defects, including point and extended imperfections. Reducing and mitigating non‐radiative recombination defects in perovskite materials are still crucial prerequisites for achieving high performance in light‐emitting applications. Here, ethoxylated trimethylolpropane triacrylate (ETPTA) is introduced as a functional additive dissolved in antisolvent to passivate surface and bulk defects during the spinning process. The ETPTA can effectively decrease the charge trapping states by passivation and/or suppression of defects. Eventually, the perovskite films that are sufficiently passivated by ETPTA make the devices achieve a maximum external quantum efficiency (EQE) of 22.49%. To our knowledge, these are the most efficient green PeLEDs up to now. In addition, a threefold increase in the T 50 operational time of the devices was observed, compared to control samples. These findings provide a simple and effective strategy to make highly efficient perovskite polycrystalline films and their optoelectronics devices.

Abstract Background Neuronal pyroptosis and neuroinflammation with excess microglial activation are widely involved in the early pathological process of ischemic stroke. Repetitive transcranial magnetic stimulation (rTMS), as a non-invasive neuromodulatory technique, has recently been reported to be anti-inflammatory and regulate microglial function. However, few studies have elucidated the role and mechanism of rTMS underlying regulating neuronal pyroptosis and microglial polarization. Methods We evaluated the motor function in middle cerebral artery occlusion/reperfusion (MCAO/r) injury mice after 1-week intermittent theta-burst rTMS (iTBS) treatment in the early phase with or without depletion of microglia by colony-stimulating factor 1 receptor (CSF1R) inhibitor treatment, respectively. We further explored the morphological and molecular biological alterations associated with neuronal pyroptosis and microglial polarization via Nissl, EdU, TTC, TUNEL staining, electron microscopy, multiplex cytokine bioassays, western blot assays, immunofluorescence staining and RNA sequencing. Results ITBS significantly protected against cerebral ischemia/reperfusion (I/R) injury-induced locomotor deficits and neuronal damage, which probably relied on the regulation of innate immune and inflammatory responses, as evidenced by RNA sequencing analysis. The peak of pyroptosis was confirmed to be later than that of apoptosis during the early phase of stroke, and pyroptosis was mainly located and more severe in the peri-infarcted area compared with apoptosis. Multiplex cytokine bioassays showed that iTBS significantly ameliorated the high levels of IL-1β, IL-17A, TNF-α, IFN-γ in MCAO/r group and elevated the level of IL-10. ITBS inhibited the expression of neuronal pyroptosis-associated proteins (i.e., Caspase1, IL-1β, IL-18, ASC, GSDMD, NLRP1) in the peri-infarcted area rather than at the border of infarcted core. KEGG enrichment analysis and further studies demonstrated that iTBS significantly shifted the microglial M1/M2 phenotype balance by curbing proinflammatory M1 activation (Iba1 + /CD86 + ) and enhancing the anti-inflammatory M2 activation (Iba1 + /CD206 + ) in peri-infarcted area via inhibiting TLR4/NFκB/NLRP3 signaling pathway. Depletion of microglia using CSF1R inhibitor (PLX3397) eliminated the motor functional improvements after iTBS treatment. Conclusions rTMS could alleviate cerebral I/R injury induced locomotor deficits and neuronal pyroptosis by modulating the microglial polarization. It is expected that these data will provide novel insights into the mechanisms of rTMS protecting against cerebral I/R injury and potential targets underlying neuronal pyroptosis in the early phase of stroke.

Brain-computer interfaces (BCIs) are used to translate brain activity signals into control signals for external devices. Currently, it is difficult for BCI systems to provide the multiple independent control signals necessary for the multi-degree continuous control of a wheelchair. In this paper, we address this challenge by introducing a hybrid BCI that uses the motor imagery-based mu rhythm and the P300 potential to control a brain-actuated simulated or real wheelchair. The objective of the hybrid BCI is to provide a greater number of commands with increased accuracy to the BCI user. Our paradigm allows the user to control the direction (left or right turn) of the simulated or real wheelchair using left- or right-hand imagery. Furthermore, a hybrid manner can be used to control speed. To decelerate, the user imagines foot movement while ignoring the flashing buttons on the graphical user interface (GUI). If the user wishes to accelerate, then he/she pays attention to a specific flashing button without performing any motor imagery. Two experiments were conducted to assess the BCI control; both a simulated wheelchair in a virtual environment and a real wheelchair were tested. Subjects steered both the simulated and real wheelchairs effectively by controlling the direction and speed with our hybrid BCI system. Data analysis validated the use of our hybrid BCI system to control the direction and speed of a wheelchair.

Synthesis planning is the process of recursively decomposing target molecules into available precursors. Computer-aided retrosynthesis can potentially assist chemists in designing synthetic routes; however, at present, it is cumbersome and cannot provide satisfactory results. In this study, we have developed a template-free self-corrected retrosynthesis predictor (SCROP) to predict retrosynthesis using transformer neural networks. In the method, the retrosynthesis planning was converted to a machine translation problem from the products to molecular linear notations of the reactants. By coupling with a neural network-based syntax corrector, our method achieved an accuracy of 59.0% on a standard benchmark data set, which outperformed other deep learning methods by >21% and template-based methods by >6%. More importantly, our method was 1.7 times more accurate than other state-of-the-art methods for compounds not appearing in the training set.

Abstract Zinc (Zn) holds great promise as a desirable anode material for next‐generation rechargeable batteries. However, the uncontrollable dendrite growth and low coulombic efficiency of the Zn plating/stripping process severely impede further practical applications of Zn‐based batteries. Here, these roadblocks are removed by using in situ grown zeolitic imidazolate framework‐8 (ZIF‐8) as the ion modulation layer to tune the diffusion behavior of Zn 2+ ions on Zn anodes. The well‐ordered nanochannels and N species of ZIF‐8 can effectively homogenize Zn 2+ flux distribution and modulate the plating/stripping rate, ensuring uniform Zn deposition without dendrite growth. The Zn corrosion and hydrogen evolution are also alleviated by the insulating nature of ZIF‐8, resulting in high coulombic efficiency. Therefore, the Zn@ZIF anode shows highly reversible, dendrite‐free Zn plating/stripping behavior under a broad range of current densities, and a symmetric cell using this anode can work correctly up to 1200 h with a low polarization at 2 mA cm −2 . Moreover, this ultrastable Zn@ZIF anode also enables a full Zn ion battery with outstanding cyclic stability (10 000 cycles).

Abstract MXene, an emerging family of 2D transition metal carbides/nitride (MXene) materials, has attracted growing attention since its initial discovery in 2011. Owing to their extraordinary electrical conductivity, high mechanical stability, various functional groups, and large interlayer space, MXene and MXene‐based nanomaterials have shown significant energy‐storage capability. Firstly, research progress on the preparation strategies and properties of MXene are summarized. Secondly, the current state‐of‐the‐art advances of MXene and MXene‐based nanomaterials as advanced electrodes for energy storage devices, including lithium‐ion batteries, sodium‐ion batteries, potassium‐ion batteries, and supercapacitors are reviewed. Finally, the key challenges and perspectives for further enhancing their electrochemical performances are also outlined. This Progress Report offers a reference and scientific inspiration for the design and preparation of high‐performance MXene and MXene‐based nanomaterials to meet the increasing need for next‐generation energy‐storage systems.

A phylogenetic tree for acrodont lizards (Chamaeleonidae and Agamidae) is established based on 1434 bases (1041 informative) of aligned DNA positions from a 1685-1778 base pair region of the mitochondrial genome. Sequences from three protein-coding genes (ND1, ND2, and COI) are combined with sequences from eight intervening tRNA genes for samples of 70 acrodont taxa and two outgroups. Parsimony analysis of nucleotide sequences identifies eight major clades in the Acrodonta. Most agamid lizards are placed into three distinct clades. One clade is composed of all taxa occurring in Australia and New Guinea; Physignathus cocincinus from Southeast Asia is the sister taxon to the Australia-New Guinea clade. A second clade is composed of taxa occurring from Tibet and the Indian Subcontinent east through South and East Asia. A third clade is composed of taxa occurring from Africa east through Arabia and West Asia to Tibet and the Indian Subcontinent. These three clades contain all agamid lizards except Uromastyx, Leiolepis, and Hydrosaurus, which represent three additional clades of the Agamidae. The Chamaeleonidae forms another clade weakly supported as the sister taxon to the Agamidae. All eight clades of the Acrodonta contain members occurring on land masses derived from Gondwanaland. A hypothesis of agamid lizards rafting with Gondwanan plates is examined statistically. This hypothesis suggests that the African/West Asian clade is of African or Indian origin, and the South Asian clade is either of Indian or Southeast Asian origin. The shortest tree suggests a possible African origin for the former and an Indian origin for the latter, but this result is not statistically robust. The Australia-New Guinea clade rafted with the Australia-New Guinea plate and forms the sister group to a Southeast Asian taxon that occurs on plates that broke from northern Australia-New Guinea. Other acrodont taxa are inferred to be associated with the plates of Afro-Arabia and Madagascar (Chameleonidae), India (Uromastyx), or southeast Asia (Hydrosaurus and Leiolepis). Introduction of different biotic elements to Asia by way of separate Gondwanan plates may be a major theme of Asian biogeography. Three historical events may be responsible for the sharp faunal barrier between Southeast Asia and Australia-New Guinea, known as Wallace's line: (1) primary vicariance caused by plate separations; (2) secondary contact of Southeast Asian plates with Eurasia, leading to dispersal from Eurasia into Southeast Asia, and (3) dispersal of the Indian fauna (after collision of that subcontinent) to Southeast Asia. Acrodont lizards show the first and third of these biogeographic patterns and anguid lizards exhibit the second pattern. Modern faunal diversity may be influenced primarily by historical events such as tectonic collisions and land bridge connections, which are expected to promote episodic turnover of continental faunas by introducing new faunal elements into an area. Repeated tectonic collisions may be one of the most important phenomena promoting continental biodiversity. Phylogenetics is a powerful method for investigating these processes.

Abstract Sun, wind and tides have huge potential in providing us electricity in an environmental-friendly way. However, its intermittency and non-dispatchability are major reasons preventing full-scale adoption of renewable energy generation. Energy storage will enable this adoption by enabling a constant and high-quality electricity supply from these systems. But which storage technology should be considered is one of important issues. Nowadays, great effort has been focused on various kinds of batteries to store energy, lithium-related batteries, sodium-related batteries, zinc-related batteries, aluminum-related batteries and so on. Some cathodes can be used for these batteries, such as sulfur, oxygen, layered compounds. In addition, the construction of these batteries can be changed into flexible, flow or solid-state types. There are many challenges in electrode materials, electrolytes and construction of these batteries and research related to the battery systems for energy storage is extremely active. With the myriad of technologies and their associated technological challenges, we were motivated to assemble this 2020 battery technology roadmap.

While tremendous efforts have been dedicated to developing environmentally friendly films made from natural polymers and renewable resources, in particular, multifunctional films featuring extraordinary mechanical properties, optical performance, and ordered nanostructure, challenges still remain in achieving all these characteristics in a single material via a scalable process. Here, we designed a green route to fabricating strong, super tough, regenerated cellulose films featuring tightly stacked and long-range aligned cellulose nanofibers self-assembled from cellulose solution in alkali/urea aqueous systems. The well-aligned nanofibers were generated by directionally controlling the aggregation of cellulose chains in the hydrogel state using a preorientation-assisted dual cross-linking approach; i.e., a physical cross-linking was rapidly introduced to permanently reserve the temporarily aligned nanostructure generated by preorienting the covalent cross-linked gels. After a structural densification in air-drying of hydrogel, high strength was achieved, and more importantly, a record-high toughness (41.1 MJ m–3) in anisotropic nanofibers-structured cellulose films (ACFs) was reached. Moreover, the densely packed and well-aligned cellulose nanofibers significantly decreased the interstices in the films to avoid light scattering, granting ACFs with high optical clarity (91%), low haze (<3%), and birefringence behaviors. This facile and high-efficiency strategy might be very scalable in fabricating high-strength, super tough, and clear cellulose films for emerging biodegradable next-generation packaging, flexible electronic, and optoelectronic applications.