Showing papers on "Iodide published in 2021"
TL;DR: In this paper, the stabilization of black-phase formamidinium lead iodide (α-FAPbI3) perovskite under various environmental conditions is considered necessary for solar cells.
Abstract: The stabilization of black-phase formamidinium lead iodide (α-FAPbI3) perovskite under various environmental conditions is considered necessary for solar cells. However, challenges remain regarding the temperature sensitivity of α-FAPbI3 and the requirements for strict humidity control in its processing. Here we report the synthesis of stable α-FAPbI3, regardless of humidity and temperature, based on a vertically aligned lead iodide thin film grown from an ionic liquid, methylamine formate. The vertically grown structure has numerous nanometer-scale ion channels that facilitate the permeation of formamidinium iodide into the lead iodide thin films for fast and robust transformation to α-FAPbI3 A solar cell with a power-conversion efficiency of 24.1% was achieved. The unencapsulated cells retain 80 and 90% of their initial efficiencies for 500 hours at 85°C and continuous light stress, respectively.
385 citations
TL;DR: In this paper, the authors improved the photostability by adding slightly excessive AX (at a molar percentage of 0.25% to Pb2+ ions), where A is formamidinium or caesium and X is iodine.
Abstract: Formamidinium–caesium mixed-cation perovskites have shown better thermal stability than their methylammonium-containing counterparts but they suffer from photoinstability induced by iodide migration and phase segregation. Here we improve their photostability by adding slightly excessive AX (at a molar percentage of 0.25% to Pb2+ ions), where A is formamidinium or caesium and X is iodine. The excessive AX does not improve the initial solar cell efficiency. It compensates iodide vacancies and suppresses ion migration and defects generation during long-term illumination by around tenfold compared with AX-deficient devices. Consequently, generation of hole traps and phase segregation is impeded, with the former limiting solar cell efficiency after degradation. The perovskite mini-modules reached a certified stabilized efficiency of 18.6% with an aperture area of ~30 cm2, corresponding to an active area efficiency of 20.2%. The mini-module maintains 93.6% of the initial efficiency after continuous operation under 1 sun illumination for >1,000 h at 50 ± 5 °C in air. Methylammonium-free perovskite solar cells have achieved promising efficiency and thermal stability yet iodide migration limits their operational stability. Deng and colleagues show that an excess of formamidinium or caesium iodide precursor suppresses iodide vacancies preventing ion migration and eventually the generation of hole traps during device operation.
173 citations
TL;DR: In this paper, the authors developed nitrogen-doped fluorescent carbon dots (NCDs) as a multi-mechanism detection for iodide and curcumin in actual complex biological and food samples, which was prepared by a one-step solid phase synthesis using tartaric acid and urea as precursors without adding any other reagents.
143 citations
TL;DR: Park et al. as discussed by the authors found that isopropylammonium stabilizes the perovskite structure and leads to solar cells with 2,000-h stability under constant illumination.
Abstract: Formamidinium lead triiodide (FAPbI3) perovskite solar cells (PSCs) are mainly fabricated by sequentially coating lead iodide and formamidinium iodide, or by coating a solution in which all components are dissolved in one solvent (one-pot process). The PSCs produced by both processes exhibited similar efficiencies; however, their long-term stabilities were notably different. We concluded that the major reason for this behaviour is the stabilization of the α-FAPbI3 phase by isopropylammonium cations produced by the chemical reaction between isopropyl alcohol, used as solvent, and methylammonium chloride, added during the process. On this basis, we fabricated PSCs by adding isopropylammonium chloride to the perovskite precursor solution for the one-pot process and achieved a certified power conversion efficiency of 23.9%. Long-term operational current density–voltage measurements (one sweep every 84 min under 1-Sun irradiation in nitrogen atmosphere) showed that the as-fabricated device with an initial efficiency of approximately 20% recorded an efficiency of about 23% after 1,000 h that gradually degraded to about 22% after an additional 1,000 h. The operational stability of formamidinium lead triiodide solar cells varies with the fabrication method of the perovskite layer. Now Park et al. find that isopropylammonium stabilizes the perovskite structure and leads to solar cells with 2,000-h stability under constant illumination.
122 citations
71 citations
TL;DR: In this paper, a surface iodide management strategy was developed through the use of cesium sulfonate to stabilize the perovskite surface, which could reduce the commonly existing surface defects and nonradiative recombination.
Abstract: Owing to the ionic nature of lead halide perovskites, their halide-terminated surface is unstable under light-, thermal-, moisture-, or electric-field-driven stresses, resulting in the formation of unfavorable surface defects. As a result, nonradiative recombination generally occurs on perovskite films and deteriorates the efficiency, stability, and hysteresis performances of perovskite solar cells (PSCs). Here, a surface iodide management strategy was developed through the use of cesium sulfonate to stabilize the perovskite surface. It was found that the pristine surface of common perovskite was terminated with extra iodide, that is, with an I-/Pb2+ ratio larger than 3, explaining the origination of surface-related problems. Through post-treatment of perovskite films by cesium sulfonate, the extra iodide on the surface was facilely removed and the as-exposed Pb2+ cations were chelated with sulfonate anions while maintaining the original 3D perovskite structure. Such iodide replacement and lead chelating coordination on perovskite could reduce the commonly existing surface defects and nonradiative recombination, enabling assembled PSCs with an efficiency of 22.06% in 0.12 cm2 cells and 18.1% in 36 cm2 modules with high stability.
68 citations
TL;DR: In this paper, a simple ammonium iodide salt in amide solvent catalyzes regioselective decarboxylative alkylation of C(sp3)-H bonds of N-aryl glycine derivatives, and cascade radical addition to unsaturated bond followed by intramolecular addition to arene.
Abstract: A simple ammonium iodide salt in amide solvent catalyzes regioselective decarboxylative alkylation of C(sp3)-H bonds of N-aryl glycine derivatives, of C(sp2)-H bond of heteroarenes, and cascade radical addition to unsaturated bond followed by intramolecular addition to arene, with a broad scope of N-hydroxyphthalimide derived redox active esters under visible light irradiation. The reactions are suggested to proceed through photoactivation of a transiently assembled chromophore from electron-deficient phthalimide moiety and iodide anion through an anion-π interaction in solvent cage followed by diffusion to generate solvated free radical species to react with C-H substrates The simplicity, practicality, and broad substrate scope of this method highlight the synthetic power of photocatalysis through transiently assembled chromophore, and will hopefully inspire further developments of low cost photocatalysis based on various non-covalent interactions, which are prevalent in supramolecular chemistry and biosystems, for sustainable organic synthesis.
49 citations
TL;DR: In this article, two ionic liquids (ILs), Ipyr-C3H7 and C5H11, were evaluated as mixed-type inhibitors with anodic predominance and achieved an inhibition efficiency of around 88%.
43 citations
TL;DR: In this article, the σ-hole effect was used to facilitate the visible-light-triggered photolysis of phosphonium iodide salts, a charge-transfer complex, selectively giving fluoromethyl radicals.
Abstract: The sigma (σ)-hole effect has emerged as a promising tool to construct novel architectures endowed with new properties. A simple yet effective strategy for the generation of monofluoromethyl radicals is a continuing challenge within the synthetic community. Fluoromethylphosphonium salts are easily available, air- and thermally stable, as well as simple-to-handle. Herein, we report the ability of the σ-hole effect to facilitate the visible-light-triggered photolysis of phosphonium iodide salts, a charge-transfer complex, selectively giving fluoromethyl radicals. The usefulness and versatility of this new protocol are demonstrated through the mono-, di-, and trifluoromethylation of a variety of alkenes.
41 citations
TL;DR: In this paper, a carbon nanotube (CNT)-incorporated MAPI3 perovskite film made in ambient air was employed as an effective absorber layer.
34 citations
TL;DR: In this paper, the solid-solid phase transition occurring during the two-step sequential deposition of methylammonium lead iodide and formamidinium-lead iodide was investigated using metadynamics, x-ray diffraction and Raman spectroscopy.
Abstract: It is well established that the lack of understanding the crystallization process in a two-step sequential deposition has a direct impact on efficiency, stability, and reproducibility of perovskite solar cells. Here, we try to understand the solid-solid phase transition occurring during the two-step sequential deposition of methylammonium lead iodide and formamidinium lead iodide. Using metadynamics, x-ray diffraction, and Raman spectroscopy, we reveal the microscopic details of this process. We find that the formation of perovskite proceeds through intermediate structures and report polymorphs found for methylammonium lead iodide and formamidinium lead iodide. From simulations, we discover a possible crystallization pathway for the highly efficient metastable α phase of formamidinium lead iodide. Guided by these simulations, we perform experiments that result in the low-temperature crystallization of phase-pure α-formamidinium lead iodide.
TL;DR: The acute toxicity assay of Vibrio fischeri indicated that transformation products by UV/sulfite under aerobic conditions were less toxic than that by direct UV photolysis.
TL;DR: Iodide adsorbents in the form of filters with high adsorption capacity, selectivity, and ability over a wide pH range are potentially useful for removing iodide from water.
TL;DR: Layered hybrid organic-inorganic perovskites such as the lead halide Ruddlesden-Popper (RP) series are solution-processable two-dimensional (2D) materials with tunable optoelectronic properties.
Abstract: Layered hybrid organic–inorganic perovskites such as the lead halide Ruddlesden–Popper (RP) series are solution-processable two-dimensional (2D) materials with tunable optoelectronic properties. Dy...
TL;DR: Iodine is a critical trace element involved in many diverse and important processes in the Earth system as mentioned in this paper, and the importance of iodine for human health has been known for over a century, with low iodine levels.
Abstract: Iodine is a critical trace element involved in many diverse and important processes in the Earth system. The importance of iodine for human health has been known for over a century, with low iodine...
TL;DR: In this paper, the incorporation of a certain amount of Cl ions into methylammonium lead iodide (MAPbI3) perovskite films and how these incorporated Cl ions affect the structural and electronic properties of these films have been investigated.
Abstract: The incorporation of a certain amount of Cl ions into methylammonium lead iodide (MAPbI3) perovskite films and how these incorporated Cl ions affect the structural and electronic properties of these films have been an intensively studied topic. In this study, we comprehensively investigated Cl incorporation in MAPbI3 at the atomic scale by a combined study of scanning tunneling microscopy, X-ray photoelectron spectroscopy, ultraviolet and inverse photoemission spectroscopy, density functional theory and molecular dynamics calculations. At a Cl concentration of 14.8 ± 0.6%, scanning tunneling microscopy images confirm the incorporation of Cl ions on the MAPbI3 surface, which also corresponds to the highest surface stability of MAPbI3 found from the viewpoint of both thermodynamics and kinetics by density functional theory and molecular dynamics calculations. Our results show that the Cl concentration is crucial to the surface bandgap and stability of MAPbI3.
TL;DR: In this article, a stable millimeter-level bismuth-based polymer composite beads (δ-Bi2O3@PES) with fast removal kinetics and high adsorption capacities for both iodide (I−) and iodate (IO3−) was reported.
02 Sep 2021
TL;DR: Abnormal amounts of small molecules in biological systems such as iodide ions (I−) might be the critical presage of some diseases and hazardous to human somatic function and played an important role as mentioned in this paper.
Abstract: Abnormal amounts of small molecules in biological systems such as iodide ions (I–) might be the critical presage of some diseases and hazardous to human somatic function and played an important rol...
TL;DR: In this article, a core-shell ZnO@Cu2O (ZC) encapsulated Ag nanoparticles (Ag NPs) nanocomposites have been fabricated via a facile one-step self-assembly process and an environmentally friendly technique.
TL;DR: In this paper, a stable α-FAPbI3 perovskite phase is achieved by employing benzylammonium iodide (BzI) and the microscopic structure is elucidated by using solid-state NMR spectroscopy and X-ray scattering measurements.
Abstract: There is an ongoing surge of interest in the use of formamidinium (FA) lead iodide perovskites in photovoltaics due to their exceptional optoelectronic properties. However, thermodynamic instability of the desired cubic perovskite (α-FAPbI3) phase at ambient conditions leads to the formation of a yellow non-perovskite (δ-FAPbI3) phase that compromises its utility. A stable α-FAPbI3 perovskite phase is achieved by employing benzylammonium iodide (BzI) and the microscopic structure is elucidated by using solid-state NMR spectroscopy and X-ray scattering measurements. Perovskite solar cells based on the FAPbI3(BzI)0.25 composition achieve power conversion efficiencies exceeding 20%, which is accompanied by enhanced shelf-life and operational stability, maintaining 80% of the performance after one year at ambient conditions.
TL;DR: In this paper, the processes that cause solution-phase anisotropic growth of metal nanostructures are not fully understood and control over the shape of a metal nano-structures grants control over its properties.
Abstract: Control over the shape of a metal nanostructure grants control over its properties, but the processes that cause solution-phase anisotropic growth of metal nanostructures are not fully understood. ...
TL;DR: In this article, the ion fluxes at the interfaces of various porous carbon electrodes/aqueous solutions of alkali metal cations (Na+, K+ and Rb+) and iodide anions, monitored by an electrochemical quartz crystal microbalance (EQCM), have been investigated.
Abstract: This paper reports on the ion fluxes at the interfaces of various porous carbon electrodes/aqueous solutions of alkali metal cations (Na+, K+ and Rb+) and iodide anions, monitored by an electrochemical quartz crystal microbalance (EQCM). Different electrode material compositions as well as various electrolyte concentrations have also been considered. By tracking the ions during electrochemical polarization, we aimed to identify the reasons for the fading capacitor performance that occurs during long-term operation. The mass change profile suggests that hydroxide anions are responsible for counterbalancing the charge stored on the negative electrode. Furthermore, we found that iodide-based species are physically adsorbed on the carbon surface immediately after the electrodes come into contact with the electrolyte, regardless of the textural properties of the activated carbon used or electrode composition. Apart from the qualitative description, the mass change profiles allow the sequence of pore occupation to be determined. Additionally, the solvation numbers for alkali metals (Na+, K+ and Rb+) and hydroxide-based species have been determined. It is claimed that the solvation number is strongly affected by the electrolyte composition. Apparently, the concentration of water molecules available in the electrolyte cannot be neglected. The outcome of this research has fundamental and application context.
TL;DR: DFT calculations were performed to rationalize the mechanism and the high efficiency of the phenol‐based phosphonium iodide catalyst, which confirmed the activation of the epoxide via hydrogen bonding for the iodide salt, which facilitates the ring‐opening step.
Abstract: A series of hydroxy-functionalized phosphonium salts were studied as bifunctional catalysts for the conversion of CO2 with epoxides under mild and solvent-free conditions. The reaction in the presence of a phenol-based phosphonium iodide proceeded via a first order rection kinetic with respect to the substrate. Notably, in contrast to the aliphatic analogue, the phenol-based catalyst showed no product inhibition. The temperature dependence of the reaction rate was investigated, and the activation energy for the model reaction was determined from an Arrhenius-plot (Ea =39.6 kJ mol-1 ). The substrate scope was also evaluated. Under the optimized reaction conditions, 20 terminal epoxides were converted at room temperature to the corresponding cyclic carbonates, which were isolated in yields up to 99 %. The reaction is easily scalable and was performed on a scale up to 50 g substrate. Moreover, this method was applied in the synthesis of the antitussive agent dropropizine starting from epichlorohydrin and phenylpiperazine. Furthermore, DFT calculations were performed to rationalize the mechanism and the high efficiency of the phenol-based phosphonium iodide catalyst. The calculation confirmed the activation of the epoxide via hydrogen bonding for the iodide salt, which facilitates the ring-opening step. Notably, the effective Gibbs energy barrier regarding this step is 97 kJ mol-1 for the bromide and 72 kJ mol-1 for the iodide salt, which explains the difference in activity.
TL;DR: In this article, a novel approach to the zinc oxide surface modification with methylammonium iodide that suppresses further reactions with the adjacent perovskite absorber layer was presented.
TL;DR: In this paper, the peak areas of both iodate and iodide ions were calculated by ion chromatography and the total iodate was determined by combining the peak regions of both ions.
TL;DR: In this article, enamides and silyl enol ethers were alkylated to deliver products of N-acyl imines and ketones in the presence of a catalytic amount of TBAI under irradiation with purple light-emitting diodes (427 nm) at room temperature.
Abstract: Enamides and silyl enol ethers were alkylated to deliver products of N-acyl imines and ketones in the presence of a catalytic amount of N-tetrabutylammonium iodide (TBAI) under irradiation with purple light-emitting diodes (427 nm) at room temperature. A broad scope of tertiary, secondary, and primary alkylation products was achieved with good yields and tolerance of a variety of functional groups. The reactions proceed through the photoactivation of a transiently assembled electron donor–acceptor complex formed between iodide and N-(acyloxy)phthalimide to generate alkyl radicals. The simplicity and low-cost nature of these methods without using metal catalysts demonstrate the practicality of the use of alkyl carboxylates as alkyl sources in organic synthesis.
TL;DR: In this paper, a multipurpose sponge-like porous matrix of a metal-organic gel to host a substantial amount of an iodine-based catholyte and uniform distribution of iodine with controlled iodide diffusion is introduced.
Abstract: Rechargeable aqueous zinc-iodine batteries (AZIBs) represent excellent zinc-iodine redox chemistry and emerged as a promising aspirant due to their high safety, low cost, ease of fabrication, and high energy density. Nevertheless, the high-dissolution-induced iodide diffusion toward the zinc anode brings the self-discharge, which governs the capacity fading and poor cycling life of the battery. Herein, a multipurpose sponge-like porous matrix of a metal-organic gel to host a substantial amount of an iodine-based catholyte and uniform distribution of iodine with controlled iodide diffusion is introduced. Limiting the iodine diffusion due to increased viscosity provides superior electrochemical performance of this promising cathode for solid-state AZIBs. As a result, AZIBs delivering high performance and long-term stability are fabricated with a capacity of 184.9 mA h g-1 with a superior capacity retention of 95.8% even after 1500 cycles at 1 C rate. The unique concept of self-discharge protection is successfully evaluated. Prototype flexible band-aid-type AZIBs were fabricated, which delivered 166.4 mA h g-1 capacity in the bending state, and applied to real-scale wearable applications.
TL;DR: An efficient technique was proposed for the elimination of iodide using nanowhisker zero-valent copper (nwZVC) decorated ZnO nanocomposites obtained by two steps pyrolysis of Cu-Zn bimetal ZIFs precursors and the resultant materials exhibited high adsorption capacity, high selectivity, strong acidity resistance and an excellent reusability.