In this work, BV RI light curves of 55 Type II supernovae (SNe II) from the Lick Observatory Supernova Search program obtained with the Katzman Automatic Imaging Telescope and the 1 m Nickel ...telescope from 2006 to 2018 are presented. Additionally, more than 150 spectra gathered with the 3 m Shane telescope are published. We conduct an analyse of the peak absolute magnitudes, decline rates, and time durations of different phases of the light and colour curves. Typically, our light curves are sampled with a median cadence of 5.5 days for a total of 5093 photometric points. In average V-band plateau declines with a rate of 1.29 mag (100 days)-1, which is consistent with previously published samples. For each band, the plateau slope correlates with the plateau length and the absolute peak magnitude: SNe II with steeper decline have shorter plateau duration and are brighter. A time-evolution analysis of spectral lines in term of velocities and pseudoequivalent widths is also presented in this paper. Our spectroscopic sample ranges between 1 and 200 days post-explosion and has a median ejecta expansion velocity at 50 days post-explosion of 6500 km/s (Halpha line) and a standard dispersion of 2000 km/s. Nebular spectra are in good agreement with theoretical models using a progenitor star having a mass <16 Msol. All the data are available to the community and will help to understand SN II diversity better, and therefore to improve their utility as cosmological distance indicators.
Perovskite solar cells (PSCs) have recently demonstrated a rapid power conversion efficiency of above 25%. In terms of physical properties, SnO2 is similar to TiO2 but with stronger charge extraction ...at the interface. Furthermore, the SnO2 electron transporting layer (ETL) is prepared using new, simple, and efficient methods, resulting in high-performance PSCs. This review initially described recent progress in SnO2 nanostructures and preparation methods. The passivation options were then divided into elemental doping, bilayer alterations, and interfacial modifications. Finally, we discussed the challenges and limitations of SnO2 ETL-based PSCs and made recommendations for further research.
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•Two pyrene-based hole transport materials are synthesized.•The dopant-free PYR16 using in PSC achieves a higher PCE of 17% than PYR27.•PSC based on dopant-free PYR16 obtains ...excellent stability at 80 ℃ and under continuous simulated AM 1.5G sunlight soaking.
In this work, arylamine branches N4-4-Bis(4-methoxyphenyl)-aminophenyl-N1,N1-bis(4-methoxyphenyl)-1,4-benzenediamine are introduced to the 1,6- and 2,7-positions of pyrene core to afford two novel HTMs coded PYR16 and PYR27. The influence of different positions of arylamine units on the optical and electronic properties and the performance of PSCs are investigated. The perovskite solar cells (PSCs) using dopant-free PYR16 exhibite a PCE of 17.00%, which is higher than that of PYR27 (14.67%). Furthermore, the PSCs based on PYR16 obtain better stability than those using PYR27 by maintaining 98% of the initial values after 1080 h at 80 ℃ in an ambient environment in the dark and 85% of initial values after 672 h under continuous sunlight soaking in an ambient environment at 45–50 ℃.
The incredible stability of carbon-based perovskite solar cells (C-PSCs) has aroused enormous interest. However, for the paintable C-PSCs, the fill factor (FF) and power conversion efficiency (PCE) ...remain low, which is because of the insufficient contact at the interface between the perovskite and the electrode and the low conductivity of the electrode. In this work, a carbon nanotube (CNT) bridging method is introduced into the devices by adding single-walled CNTs (SWCNTs) in both perovskite and carbon layers to form a high-quality perovskite/carbon interface. The CNT bridges penetrating into both the CH3NH3PbI3 layer and the carbon cathode not only facilitate charge extraction and transport between the two layers but also promote the electrical conductivity of the carbon electrode. The hole transport layer-free C-PSC with a structure of fluorine-doped tin oxide/compact TiO2/mesoporous TiO2/CH3NH3PbI3–SWCNT/SWCNT–C gained a remarkable PCE of 15.73% with an FF of 0.72, accompanied by an outstanding stability of 90 days in the dark under high-humidity 65 ± 5% relative humidity (RH), 25 ± 5 °C and high-temperature (75 ± 5 °C, 25 ± 5% RH) conditions. The low-cost fabrication process makes highly stable and efficient C-PSCs promising candidates for future applications.
A fullerene derivative (α‐bis‐PCBM) is purified from an as‐produced bis‐phenyl‐C61‐butyric acid methyl ester (bis‐60PCBM) isomer mixture by preparative peak‐recycling, high‐performance liquid ...chromatography, and is employed as a templating agent for solution processing of metal halide perovskite films via an antisolvent method. The resulting α‐bis‐PCBM‐containing perovskite solar cells achieve better stability, efficiency, and reproducibility when compared with analogous cells containing PCBM. α‐bis‐PCBM fills the vacancies and grain boundaries of the perovskite film, enhancing the crystallization of perovskites and addressing the issue of slow electron extraction. In addition, α‐bis‐PCBM resists the ingression of moisture and passivates voids or pinholes generated in the hole‐transporting layer. As a result, a power conversion efficiency (PCE) of 20.8% is obtained, compared with 19.9% by PCBM, and is accompanied by excellent stability under heat and simulated sunlight. The PCE of unsealed devices dropped by less than 10% in ambient air (40% RH) after 44 d at 65 °C, and by 4% after 600 h under continuous full‐sun illumination and maximum power point tracking, respectively.
Significantly improved performance of mixed perovskite solar cells, using a facile α‐bis‐PCBM‐containing perovskite growth method during device fabrication, is reported. The newly developed perovskite solar cell exhibits an enhanced power conversion efficiency of 20.8%, along with enhanced stability under heat and illumination.
Semiconductor photocatalysts are widely used in environmental remediation and energy conversion processes that affect social development. These processes involve, for example, hydrogen production ...from water splitting, carbon dioxide reduction, pollutant degradation, and the conversion of raw organic chemical materials into high-value-added chemicals. Metal halide perovskites (MHPs) have become a new class of promising cheap and easy to manufacture candidate materials for use in photocatalytic semiconductors due to their advantages of high extinction coefficients, optimal band gaps, high photoluminescence quantum yields, and long electron-hole diffusion lengths. However, their unstable ion-bonded crystal structures (very low theoretical decomposition energy barriers) limit their widespread application. In this review, we introduce the physical properties of MHP materials suitable for photocatalysis, and MHP-based photocatalytic particle suspension systems, photoelectrode thin film systems, and photovoltaic-photo(electro)chemical systems. Then, numerous studies realizing efficient and stable photocatalytic water splitting, carbon dioxide reduction, organic conversion, and other reactions involving MHP materials were highlighted. In addition, we conducted rigorous analysis of the potential problems that could hinder progress in this new scientific research field, such as Pb element toxicity and material instability. Finally, we outline the potential opportunities and directions for photocatalysis research based on MHPs.
We introduce the physical properties of MHP materials suitable for photocatalysis, and MHP-based photocatalytic systems.
Poor crystallinity of perovskite and extensive defects around grain boundaries are the acknowledged hindrances to obtaining high efficiency and long‐term stability for organic metal halide perovskite ...solar cells (PSCs). Here, a 2D covalent organic framework (2D COF) nanosheets, (TPA)1(TPhT)1CN, is first in situ synthesized in a PbI2 layer with a highly crystalline structure to precisely regulate the crystallization process of perovskite in the sequential deposition method. The existence of 2D COF nanosheets can decelerate intermolecular interdiffusion and induce perovskite crystals to grow along (110) planes with enlarged grain size. Meanwhile, 2D COF nanosheets distributed around the grain boundaries reduce the defect density and promote carriers transporting in the perovskite film. The superior properties of the perovskite film afford the champion PSC device with a power conversion efficiency of 22.04%, which is over 10% higher than the control device. Moreover, the target PSC also demonstrates outstanding long‐term stability. It can maintain over 90% of its initial value after 90 days storage in ambient conditions for unencapsulated devices. This work paves a new path for regulating the crystallization process of perovskites via 2D crystalline materials.
A 2D donor–acceptor covalent organic framework nanosheet, (TPA)1(TPhT)1CN, is in situ synthesized in a lead iodide layer to regulate the crystallization process of a perovskite film in a sequential deposition method. A covalent organic framework incorporated perovskite solar cell is endowed with a prominent power conversion efficiency of 22.04% and excellent stability.
Pyridinyl-triazole ligand systems (including N2-2-pyridinyl 1,2,3-triazoles and N1/N2-substituted 2-(NH-1,2,3-triazol-4-yl)pyridines) were found to be superior ligands for CuI-catalyzed azide-alkyne ...cycloaddition (CuAAC) reactions. Low catalyst loadings, short reaction times, facile catalyst recyclability, ambient temperature, and open-flask conditions made this catalytic system very practical. The iodide anions could form iodine bridges to construct stable dinuclear Cu(I) complexes with these ligands, which was the key to achieve high catalytic activities. While CuBr and CuCl were not suitable for this ligand system because of the improper size of Br and Cl atoms for the formation of the corresponding dinuclear Cu(I) complexes.
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•A simple pyridinyl-triazole ligand system for CuI-catalyzed AAC reactions.•Dinuclear Cu(I) complex with Cu2(μ-I)2 core as efficient catalysis.•Simple and mild reaction conditions and facile recyclable catalyst.
Hole injection/transport layer-free organic light-emitting diodes (HIL/HTL-free OLEDs) are highly anticipated due to their simpler fabrication process, lower material cost and no interlayer ...intermixing in solution-processed OLEDs. This study presents a comprehensive strategy to obtain HIL/HTL-free OLEDs. Here, indium tin oxide (ITO) was modified by self-assembled monolayer (SAM) of various phosphoric acids (PAs). The effect of work function, PA content and PA conductivity on the hole injection from the modified ITOs was systematically studied, it was found that PA conductivity plays a decisive role. By comparation, it was revealed that pentafluorobenzyl phosphonic acid modified ITO (F5BnPA-ITO) could provide the highest hole injection. Moreover, exciton quenching near the ITO was effectively suppressed by F5BnPA SAM together with adjusting device structure. Resultantly, solution-processed phosphorescent OLEDs based on F5BnPA-ITO achieved a maximum power efficiency of 63.13 lm W−1 and preferable current efficiency of 60.32 cd A−1, which is the state-of-the-art among the reported solution-processed OLEDs with similar emitters. This contribution is the first to report that HIL/HTL-free OLEDs achieved preferable performance than standard multilayered devices.
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•For the first time, hole injection/transport layer-free OLEDs were achieved with preferable performance.•The solution-processed phosphorescent OLED achieved a maximum power efficiency of 63.13 lm W−1.•It was confirmed that the conductivity and the content of modifiers play decisive roles in hole injection.
All-inorganic perovskite quantum dots (PQDs) have attracted great attention in optoelectronic applications. However, compared with green and red PQDs, the poor photoluminescence quantum yield (PLQY) ...and terrible external quantum efficiencies (EQE) of blue-emission PQDs light-emitting diodes (QLEDs) have limited their further development in display field. Here, a general strategy for enhancing PLQY and EQE through lanthanum ions doping is proposed. Density functional theory (DFT) calculations confirmed that the partial substitution of La3+ for Pb2+ leads to a reduced defect states and an increased radiative recombination, meanwhile, a higher carrier temperature and exciton binding energy are also obtained. In consequence, a maximum PLQY of 84.3% is obtained for La3+-doped CsPb(BrxCl1-x)3 PQDs with emissions ranging from 448 to 500 nm. In terms of devices, phase separation and ion migration are effectively alleviated with La3+ profiting from the constricted lattice and stronger interaction between La and Cl. Resultantly, QLEDs with La3+-doped PQDs show the maximum EQE of 2.17% (480 nm) and 3.25% (489 nm), which is higher than state-of-the-art records at this wavelength.
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•The introduction of La3+ causes the contraction of octahedral, enhancing the short-range order of perovskite lattice.•A reduction of defect states as well as an increased PLQY of blue-emission CsPb(BrxCl1-x)3 PQDs can be obtained.•QLEDs based on La3+-doped PQDs exhibits a superior EQE of 3.25% and a suppressed phase separation characteristic.
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