Korea Research Institute of Chemical Technology

The band gap of formamidinium lead iodide (FAPbI3) perovskites allows broader absorption of the solar spectrum relative to conventional methylammonium lead iodide (MAPbI3). Because the optoelectronic properties of perovskite films are closely related to film quality, deposition of dense and uniform films is crucial for fabricating high-performance perovskite solar cells (PSCs). We report an approach for depositing high-quality FAPbI3 films, involving FAPbI3 crystallization by the direct intramolecular exchange of dimethylsulfoxide (DMSO) molecules intercalated in PbI2 with formamidinium iodide. This process produces FAPbI3 films with (111)-preferred crystallographic orientation, large-grained dense microstructures, and flat surfaces without residual PbI2. Using films prepared by this technique, we fabricated FAPbI3-based PSCs with maximum power conversion efficiency greater than 20%.

The formation of a dense and uniform thin layer on the substrates is crucial for the fabrication of high-performance perovskite solar cells (PSCs) containing formamidinium with multiple cations and mixed halide anions. The concentration of defect states, which reduce a cell's performance by decreasing the open-circuit voltage and short-circuit current density, needs to be as low as possible. We show that the introduction of additional iodide ions into the organic cation solution, which are used to form the perovskite layers through an intramolecular exchanging process, decreases the concentration of deep-level defects. The defect-engineered thin perovskite layers enable the fabrication of PSCs with a certified power conversion efficiency of 22.1% in small cells and 19.7% in 1-square-centimeter cells.

Chemically tuned inorganic-organic hybrid materials, based on CH3NH3(═MA)Pb(I(1-x)Br(x))3 perovskites, have been studied using UV-vis absorption and X-ray diffraction patterns and applied to nanostructured solar cells. The band gap engineering brought about by the chemical management of MAPb(I(1-x)Br(x))3 perovskites can be controllably tuned to cover almost the entire visible spectrum, enabling the realization of colorful solar cells. We demonstrate highly efficient solar cells exhibiting 12.3% in a power conversion efficiency of under standard AM 1.5, for the most efficient device, as a result of tunable composition for the light harvester in conjunction with a mesoporous TiO2 film and a hole conducting polymer. We believe that the works highlighted in this paper represent one step toward the realization of low-cost, high-efficiency, and long-term stability with colorful solar cells.

autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

copies/mL). Thus, we have successfully fabricated a promising FET biosensor for SARS-CoV-2; our device is a highly sensitive immunological diagnostic method for COVID-19 that requires no sample pretreatment or labeling.

The large-pore iron(III) carboxylate MIL-100(Fe) with a zeotype architecture has been isolated under hydrothermal conditions, its structure solved from synchrotron X-ray powder diffraction data, while Friedel-Crafts benzylation catalytic tests indicate a high activity and selectivity for MIL-100(Fe).

The coordinatively unsaturated sites in MIL-101, Cr3(F,OH)(H2O)2O[(O2C)-C6H4-(CO2)]3⋅n H2O (n≈25), having zeotypic giant pores can be selectively functionalized in a way differing from that of mesoporous silica. Metal–organic frameworks, grafted with ethylenediamine or diethylenetriamine on the unsaturated CrIII sites of MIL-101, exhibit remarkably high activities in the Knoevenagel condensation relative to that of the mesophase. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z705998_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Transporter layers for greater stability Although perovskite solar cells (PSCs) can have power conversion efficiencies exceeding 20%, they can have limited stability under ultraviolet irradiation. This is in part because the mesoporous TiO 2 used as an electron-transporting layer can photocatalyze unwanted reactions in the perovskite layer. Shin et al. report a low-temperature colloidal method for depositing La-doped BaSnO 3 films as a replacement for TiO 2 to reduce such ultraviolet-induced damage. Solar cells retained over 90% of their initial performance after 1000 hours of full sun illumination. Science , this issue p. 167

Coronavirus disease 2019 (COVID-19), which causes serious respiratory illness such as pneumonia and lung failure, was first reported in Wuhan, the capital of Hubei, China. The etiological agent of COVID-19 has been confirmed as a novel coronavirus, now known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is most likely originated from zoonotic coronaviruses, like SARS-CoV, which emerged in 2002. Within a few months of the first report, SARS-CoV-2 had spread across China and worldwide, reaching a pandemic level. As COVID-19 has triggered enormous human casualties and serious economic loss posing global threat, an understanding of the ongoing situation and the development of strategies to contain the virus's spread are urgently needed. Currently, various diagnostic kits to test for COVID-19 are available and several repurposing therapeutics for COVID-19 have shown to be clinically effective. In addition, global institutions and companies have begun to develop vaccines for the prevention of COVID-19. Here, we review the current status of epidemiology, diagnosis, treatment, and vaccine development for COVID-19.

Recent ideas concerning site-selective functionalization of chromium terephtha-late MIL-101 are discussed, focusing on the utilization of unsaturated Cr(III) sites (see image). Recent advances in synthesis, selective surface functionalization, outstanding sorption properties, encapsulation of nanoobjects, and catalytic applications in MIL-101 are also discussed.

Electrolyte cation size is known to influence the electrochemical reduction of CO2 over metals; however, a satisfactory explanation for this phenomenon has not been developed. We report here that these effects can be attributed to a previously unrecognized consequence of cation hydrolysis occurring in the vicinity of the cathode. With increasing cation size, the pKa for cation hydrolysis decreases and is sufficiently low for hydrated K+, Rb+, and Cs+ to serve as buffering agents. Buffering lowers the pH near the cathode, leading to an increase in the local concentration of dissolved CO2. The consequences of these changes are an increase in cathode activity, a decrease in Faradaic efficiencies for H2 and CH4, and an increase in Faradaic efficiencies for CO, C2H4, and C2H5OH, in full agreement with experimental observations for CO2 reduction over Ag and Cu.

Abstract The most important properties of self‐healing polymers are efficient recovery at room temperature and prolonged durability. However, these two characteristics are contradictory, making it difficult to optimize them simultaneously. Herein, a transparent and easily processable thermoplastic polyurethane (TPU) with the highest reported tensile strength and toughness (6.8 MPa and 26.9 MJ m −3 , respectively) is prepared. This TPU is superior to reported contemporary room‐temperature self‐healable materials and conveniently heals within 2 h through facile aromatic disulfide metathesis engineered by hard segment embedded aromatic disulfides. After the TPU film is cut in half and respliced, the mechanical properties recover to more than 75% of those of the virgin sample within 2 h. Hard segments with an asymmetric alicyclic structure are more effective than those with symmetric alicyclic, linear aliphatic, and aromatic structures. An asymmetric structure provides the optimal metathesis efficiency for the embedded aromatic disulfide while preserving the remarkable mechanical properties of TPU, as indicated by rheological and surface investigations. The demonstration of a scratch‐detecting electrical sensor coated on a tough TPU film capable of auto‐repair at room temperature suggests that this film has potential applications in the wearable electronics industry.

To fabricate efficient formamidinium tin iodide (FASnI3) perovskite solar cells (PSCs), it is essential to deposit uniform and dense perovskite layers and reduce Sn(4+) content. Here we used solvent-engineering and nonsolvent dripping process with SnF2 as an inhibitor of Sn(4+). However, excess SnF2 induces phase separation on the surface of the perovskite film. In this work, we report the homogeneous dispersion of SnF2 via the formation of the SnF2-pyrazine complex. Consequently, we fabricated FASnI3 PSCs with high reproducibility, achieving a high power conversion efficiency of 4.8%. Furthermore, the encapsulated device showed a stable performance for over 100 days, maintaining 98% of its initial efficiency.

Large hydrogen-storage capacity at liquid-nitrogen temperature is exhibited by the metal–organic framework MIL-101. In the zeotype architecture of this porous solid (see picture) each intersection of the cages is occupied by a supertetrahedron formed by trimers of chromium octahedra assembled with benzene-1,4-dicarboxylate ligands. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2006/z600105_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

The voltage output of perovskite solar cells is found to be dependent on both the energy level of perovskite itself as a solar absorber and hole transporting materials.

Three spiro-OMeTAD derivatives have been synthesized and characterized by (1)H/(13)C NMR spectroscopy and mass spectrometry. The optical and electronic properties of the derivatives were modified by changing the positions of the two methoxy substituents in each of the quadrants, as monitored by UV-vis spectroscopy and cyclic voltammetry measurements. The derivatives were employed as hole-transporting materials (HTMs), and their performances were compared for the fabrication of mesoporous TiO2/CH3NH3PbI3/HTM/Au solar cells. Surprisingly, the cell performance was dependent on the positions of the OMe substituents. The derivative with o-OMe substituents showed highly improved performance by exhibiting a short-circuit current density of 21.2 mA/cm(2), an open-circuit voltage of 1.02 V, and a fill factor of 77.6% under 1 sun illumination (100 mW/cm(2)), which resulted in an overall power conversion efficiency (PCE) of 16.7%, compared to ~15% for conventional p-OMe substituents. The PCE of 16.7% is the highest value reported to date for perovskite-based solar cells with spiro-OMeTAD.

This study aims to understand the visible light photocatalytic activities of platinized WO3 (Pt/WO3) on the degradation of aquatic pollutants and the role of main photooxidants. The presence of Pt on WO3 is known to facilitate the multielectron reduction of O2, which enables O2 to serve as an electron acceptor despite the insufficient reduction potential of the conduction band electrons (in WO3) for the one-electron reduction of O2. The concurrent oxidative reactions occurring on WO3 were markedly enhanced in the presence of Pt and accompanied the production of OH radicals under visible light, which was confirmed by both a fluorescence method (using a chemical trap) and a spin trap method. The generation of OH radicals mainly comes from the reductive decomposition of H2O2 that is produced in situ from the reduction of O2 on Pt/WO3. The rate of in situ production of H2O2 under visible light was significantly faster with Pt/WO3 than WO3. Six substrates that were tested for the visible light (lambda>420 nm) induced degradation on Pt/WO3 included dichloroacetate (DCA), 4-chlorophenol (4-CP), tetramethylammonium (TMA), arsenite (As(III)), methylene blue (MB), and acid orange 7 (AO7). The degradation (or conversion) of all six substrates was successfully achieved with Pt/WO3 and the role of OH radicals in Pt/WO3 photocatalysis seemed to be different depending on the kind of substrate. In the presence of tert-butyl alcohol (TBA: OH radical scavenger), the photocatalytic degradation was markedly reduced for 4-CP or completely inhibited for DCA and TMA whereas that of As(III), MB, and AO7 was little affected. Pt/WO3 photocatalyst that oxidizes various substrates under visible light with a sufficient photostability can be applied for solar water treatment.

The chromium terephthalate MIL-101 has been prepared rapidly and efficiently by using microwave-assisted hydrothermal synthesis. The resulting material exhibits giant pores and very large surface areas and demonstrates a huge, rapid adsorption of benzene in both vapor (see figure) and liquid phases.

Newly developed passivation strategy results in unprecedented perovskite optoelectronic device performances.

Abstract Thermoelectric materials generate electric energy from waste heat, with conversion efficiency governed by the dimensionless figure of merit, ZT. Single-crystal tin selenide (SnSe) was discovered to exhibit a high ZT of roughly 2.2–2.6 at 913 K, but more practical and deployable polycrystal versions of the same compound suffer from much poorer overall ZT, thereby thwarting prospects for cost-effective lead-free thermoelectrics. The poor polycrystal bulk performance is attributed to traces of tin oxides covering the surface of SnSe powders, which increases thermal conductivity, reduces electrical conductivity and thereby reduces ZT. Here, we report that hole-doped SnSe polycrystalline samples with reagents carefully purified and tin oxides removed exhibit an ZT of roughly 3.1 at 783 K. Its lattice thermal conductivity is ultralow at roughly 0.07 W m –1 K –1 at 783 K, lower than the single crystals. The path to ultrahigh thermoelectric performance in polycrystalline samples is the proper removal of the deleterious thermally conductive oxides from the surface of SnSe grains. These results could open an era of high-performance practical thermoelectrics from this high-performance material.