Lead halide perovskite films have witnessed rapid progress in optoelectronic devices, whereas polycrystalline heterogeneities and serious native defects in films are still responsible for undesired ...recombination pathways, causing insufficient utilization of photon‐generated charge carriers. Here, radiation‐enhanced polycrystalline perovskite films with ultralong carrier lifetimes exceeding 6 μs and single‐crystal‐like electron–hole diffusion lengths of more than 5 μm are achieved. Prolongation of charge‐carrier activities is attributed to the electronic structure regulation and the defect elimination at crystal boundaries in the perovskite with the introduction of phenylmethylammonium iodide. The introduced electron‐rich anchor molecules around the host crystals prefer to fill the halide/organic vacancies at the boundaries, rather than form low‐dimensional phases or be inserted into the original lattice. The weakening of the electron‐phonon coupling and the excitonic features of the photogenerated carriers in the optimized films, which together contribute to the enhancement of carrier separation and transportation, are further confirmed. Finally the resultant perovskite films in fully operating solar cells with champion efficiency of 23.32% are validated and a minimum voltage deficit of 0.39 V is realized.
Ultralong charge‐carrier lifetimes >6 μs are achieved in polycrystalline halide perovskites by decorating the grain boundaries with a trace amount of electron‐rich anchors, which benefits from weak excitonic effects and the weakening of electron–phonon couplings in passivated films, fulfilling reduced voltage deficits and enhanced efficiencies in perovskite photovoltaics. This finding provides a new insight into realizing superior carrier properties of polycrystalline perovskite films and high‐performance perovskite optoelectronics.
Understanding the fundamental properties of buried interfaces in perovskite photovoltaics is of paramount importance to the enhancement of device efficiency and stability. Nevertheless, accessing ...buried interfaces poses a sizeable challenge because of their non‐exposed feature. Herein, the mystery of the buried interface in full device stacks is deciphered by combining advanced in situ spectroscopy techniques with a facile lift‐off strategy. By establishing the microstructure–property relations, the basic losses at the contact interfaces are systematically presented, and it is found that the buried interface losses induced by both the sub‐microscale extended imperfections and lead‐halide inhomogeneities are major roadblocks toward improvement of device performance. The losses can be considerably mitigated by the use of a passivation‐molecule‐assisted microstructural reconstruction, which unlocks the full potential for improving device performance. The findings open a new avenue to understanding performance losses and thus the design of new passivation strategies to remove imperfections at the top surfaces and buried interfaces of perovskite photovoltaics, resulting in substantial enhancement in device performance.
The mystery of the buried interface in perovskite photovoltaics is deciphered by combining advanced spectroscopy techniques with a lift‐off strategy. The findings open a new avenue to understanding performance losses and thus the design of unique passivation strategies to remove imperfections at the top surfaces and buried interfaces of perovskite photovoltaics, resulting in substantial enhancement in device performance.
The performance of perovskite photovoltaics is fundamentally impeded by the presence of undesirable defects that contribute to non-radiative losses within the devices. Although mitigating these ...losses has been extensively reported by numerous passivation strategies, a detailed understanding of loss origins within the devices remains elusive. Here, we demonstrate that the defect capturing probability estimated by the capture cross-section is decreased by varying the dielectric response, producing the dielectric screening effect in the perovskite. The resulting perovskites also show reduced surface recombination and a weaker electron-phonon coupling. All of these boost the power conversion efficiency to 22.3% for an inverted perovskite photovoltaic device with a high open-circuit voltage of 1.25 V and a low voltage deficit of 0.37 V (a bandgap ~1.62 eV). Our results provide not only an in-depth understanding of the carrier capture processes in perovskites, but also a promising pathway for realizing highly efficient devices via dielectric regulation.
The highest power conversion efficiencies (PCEs) reported for perovskite solar cells (PSCs) with inverted planar structures are still inferior to those of PSCs with regular structures, mainly because ...of lower open-circuit voltages (
). Here we report a strategy to reduce nonradiative recombination for the inverted devices, based on a simple solution-processed secondary growth technique. This approach produces a wider bandgap top layer and a more n-type perovskite film, which mitigates nonradiative recombination, leading to an increase in
by up to 100 millivolts. We achieved a high
of 1.21 volts without sacrificing photocurrent, corresponding to a voltage deficit of 0.41 volts at a bandgap of 1.62 electron volts. This improvement led to a stabilized power output approaching 21% at the maximum power point.
Impedance matching and attenuation principles are decisive for electromagnetic wave (EMW) absorption materials to achieve wider absorption bandwidth and higher strength absorption. By designing ...macrostructures to obtain metamaterials and tuning microstructures of absorption materials, impedance matching characteristic and absorption performance can be readily improved. In this paper, three-dimensional (3D) printing technology as well as precursor infiltration and pyrolysis (PIP) method were utilized to fabricate Al2O3/carbon nanotubes/SiC nanowires/SiOC composites with twisted cross metamaterial structures, where carbon nanotubes (CNTs) acted as a nucleating agent to obtain SiC nanowires (SiCnw) and as conductive phase to form conductive net structure, thus improving the dielectric and conductive loss of the composites. The Al2O3/CNT/SiCnw/SiOC composites achieved a minimum reflection coefficient (RCmin) value of −56.84 dB (99.999%) at 12.2 GHz with a thickness of 2.8 mm and the effective absorption bandwidth (EAB) ranges from 8.2–12.4 GHz with a thickness of 3.2 mm, covering the whole X-band. The excellent EMW absorption performance of the composite with metamaterial structure makes it possible to be practically applied.
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•Novel twisted cross metamaterial structures were successfully achieved by 3D printing.•Precursor infiltration and pyrolysis process was conducted to generate SiC nanowires@Carbon nanoutbes on the ceramics.•The introduced SiC nanowires@Carbon nanoutbes significantly enhance the dielectric and conductive loss of the composites.•The designed metamaterial structures contribute to the enhanced absorbing performance.
Abstract
Plant diseases caused by plant viruses and pathogens seriously affect crop yield and quality, and it is very difficult to control them. The discovery of new leads based on natural products ...is an important way to innovate pesticides. Based on the resveratrol is a kind of natural phytoalexin, but it cannot be used as candidate for the development of new drug due to its poor druggability. The phenolic hydroxyl groups in the resveratrol structure are easily destroyed by oxidation, in order to improve its stability, ester formation is the most commonly used modification method in drug design. Their structures were characterized by
1
H NMR,
13
C NMR and HRMS. The activity against tobacco mosaic virus (TMV) of these ester derivatives has been tested for the first time. The bioassay results showed part of the target compounds exhibited good to excellent in vivo activities against TMV. The optimum compounds
III-2
(inhibitory rates of 50, 53, and 59% at 500 μg/mL for inactivation, curative, and protection activities in vivo, respectively),
III-4
(inhibitory rates of 57, 59, and 51% at 500 μg/mL, respectively), and
II-5
(inhibitory rates of 54, 52, and 51% at 500 μg/mL, respectively) displayed higher activity than commercial plant virucide ribavirin (inhibitory rates of 38, 37, and 40% at 500 μg/mL, respectively). Compounds
I-9
and
I-10
also showed excellent activities. The systematic study provides strong evidence that these simple resveratrol derivatives could become potential TMV inhibitors. The novel concise structure provides another new template for antiviral studies.
Computational catalyst screening has the potential to significantly accelerate heterogeneous catalyst discovery. Typically, this involves developing microkinetic reactor models that are based on ...parameters obtained from density functional theory and transition-state theory. To reduce the large computational cost involved in computing various adsorption and transition-state energies of all possible surface states on a large number of catalyst models, linear scaling relations for surface intermediates and transition states have been developed that only depend on a few, typically one or two descriptors, such as the carbon atom adsorption energy. As a result, only the descriptor values have to be computed for various active site models to generate volcano curves in activity or selectivity. Unfortunately, for more complex chemistries the predictability of linear scaling relations is unknown. Also, the selection of descriptors is essentially a trial and error process. Here, using a database of adsorption energies of the surface species involved in the decarboxylation and decarbonylation of propionic acid over eight monometalic transition-metal catalyst surfaces (Ni, Pt, Pd, Ru, Rh, Re, Cu, Ag), we tested if nonlinear machine learning (ML) models can outperform the linear scaling relations in prediction accuracy when predicting the adsorption energy for various species on a metal surface based on data from the rest of the metal surfaces. We found linear scaling relations to hold well for predictions across metals with a mean-absolute error of 0.12 eV, and ML methods being unable to outperform linear scaling relations when the training dataset contains a complete set of energies for all of the species on various metal surfaces. Only when the training dataset is incomplete, namely, contains a random subset of species’ energies for each metal, a currently unlikely scenario for catalyst screening, do kernel-based ML models significantly outperform linear scaling relations. We also found that simple coordinate-free species descriptors, such as bond counts, achieve as good results as sophisticated coordinate-based descriptors. Finally, we propose an approach for automatic discovery of appropriate metal descriptors using principal component analysis.
The highest efficiencies reported for perovskite solar cells so far have been obtained mainly with methylammonium and formamidinium mixed cations. Currently, high‐quality mixed‐cation perovskite thin ...films are normally made by use of antisolvent protocols. However, the widely used “antisolvent”‐assisted fabrication route suffers from challenges such as poor device reproducibility, toxic and hazardous organic solvent, and incompatibility with scalable fabrication process. Here, a simple dual‐source precursor approach is developed to fabricate high‐quality and mirror‐like mixed‐cation perovskite thin films without involving additional antisolvent process. By integrating the perovskite films into the planar heterojunction solar cells, a power conversion efficiency of 20.15% is achieved with negligible current density–voltage hysteresis. A stabilized power output approaching 20% is obtained at the maximum power point. These results shed light on fabricating highly efficient perovskite solar cells via a simple process, and pave the way for solar cell fabrication via scalable methods in the near future.
A dual‐source precursor approach is developed to fabricate a high‐quality and mirror‐like mixed‐cation perovskite without involving additional antisolvent process. By integrating the perovskite films into the planar heterojunction solar cells, a power conversion efficiency of 20.15% is achieved with negligible hysteresis effect. A stabilized power output approaching 20% is obtained at the maximum power point.
O‐Heterocyclic structures such as 2,3‐dihydrobenzofurans are key motifs in many natural compounds and pharmaceuticals. Enantioselective formation of chiral dihydrobenzofurans and analogues was ...achieved through a copper‐catalyzed desymmetrization strategy with a chiral cyclic 1,2‐diamine. A broad range of substrates are compatible with this CuI‐diamine catalytic system and afford the desired coupling products with chiral tertiary or quaternary carbon centers in high yields and good to excellent enantioselectivities under mild conditions.
O‐Heterocyclic structures such as chiral dihydrobenzofurans can be formed enantioselectively through a copper‐catalyzed desymmetrization strategy with a chiral cyclic 1,2‐diamine ligand. A broad range of substrates is compatible with this CuI‐diamine catalytic system and afford the desired coupling products with chiral tertiary or quaternary carbon centers in high yields and good to excellent enantioselectivities under mild conditions.
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•The retrograde eclogite in Danshuiquan locality recorded clockwise P–T path.•The extensive HP–UHT overprint eliminated most of the peak stage records.•The eclogite was exhumed from ...eclogite-facies to granulite-facies within 16 Ma.•The eastern and western SAT experienced differential exhumation process.•Local mantle heating contribute to the fast exhumation in the eastern segment.
South Altyn Tagh contains ultrahigh-pressure (UHP) terranes that have been exhumed from ~300 km mantle depth. Previous zircon U–Pb geochronology has yielded an eclogite-facies age of ca. 500 Ma and a high-pressure (HP) granulite-facies retrograde age of ca. 450 Ma in the Jianggalesayi area in the western segment of South Altyn Tagh. However, in the eastern segment (Yinggelisayi and Danshuiquan localities), an age range of 500–480 Ma has been determined, and it remains uncertain as to whether this age range represents the timing of the peak metamorphic stage or the retrograde overprint. Our study of newly discovered retrograde eclogite in the Danshuiquan locality shows that it underwent three stages of metamorphism, under eclogite-facies, HP granulite-facies and amphibolite-facies P–T conditions of 2.5–4.0 GPa and 870–1050 °C, 2.0–1.4 GPa and 830–940 °C, and 0.7–1.3 GPa and 704–880 °C, respectively. The decompression-dominated P–T path evolved mainly after crossing the solidus, indicating marked retrograde modification under melt-bearing conditions. LA–ICP–MS and SIMS zircon U–Pb dating yielded ca. 500 Ma eclogite-facies and ca. 484 Ma granulite-facies retrograde ages and a later retrograde age of ca. 452 Ma. The clockwise P–T–t path indicates rapid exhumation from eclogite-facies to granulite-facies within around 16 Myr, which is faster than that of the UHP rocks in the western segment. Thus, the HP–UHP rocks in South Altyn Tagh suggest a differential exhumation process for the eastern and western segments. The distinct HP–UHT metamorphism and rapid exhumation of (U)HP rocks in the eastern segment likely resulted from local mantle heating. The continuing P–T evolution of the (U)HP rocks under UHT conditions during exhumation led to a pervasive granulite-facies overprint in the eastern segment of the South Altyn Tagh. The rapid exhumation recorded in the eastern segment provides valuable insights into the exhumation mechanism of ultra-deep subducted UHP terranes.
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