Molar Ratio Of Precursors Research Articles

Synthesis of highly branched hollow trimetallic PdAgCu nanoparticles

An aqueous, room temperature, and surfactant-less synthetic route based on galvanic replacement and co-reduction is reported to yield PdAgCu nanoparticles (NPs) with a high density of sharp and branched tips. The PdAgCu NPs are of high-purity, uniform size and more than 90% of them adopt branched tips. Besides, the PdAgCu NPs exhibit hollow interiors, well-alloyed nature, and a tuneable localized surface plasmon resonance peak in the near infrared region. Their morphology and optical property are facilely controlled by adjusting the precursor molar ratio, amounts of AgNP seeds and Cl− ions in the growth solution. The proposed synthetic approach is anticipated to offer an attractive avenue for facile synthesis of other multi-metallic and branched NPs with controlled properties.

Self-assembly of zinc cadmium sulfide nanorods into nanoflowers with enhanced photocatalytic hydrogen production activity

ZnCdS solid solutions have been extensively studied due to their excellent photocatalytic hydrogen evolution performance. The change of the molar ratio of precursors affects the morphology and structure of ZnCdS, with the subsequent influence on the separation of photogenerated electron–hole pairs and the hydrogen production ability. The effect of the amount of nonmetallic elements on the photocatalytic activity has been scarcely explored. In this work, the morphology of ZnCdS is regulated by varying the amount of thioacetamide as S precursor. The structure of the samples is thoroughly analyzed by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller analysis. Their optical properties, photocatalytic hydrogen evolution ability, and photoelectrochemical performance are evaluated. Upon increasing the amount of thioacetamide, the crystallinity improves, the ZnCdS nanorods self-assemble into nanoflowers, and the number of defects decreases. The highest photocatalytic activity is achieved for a (Zn + Cd):S molar ratio of 1:3.5. Moreover, the photocatalyst exhibits excellent stability after six cycles. The one-dimensional nanorod structure contributes to the formation of a space charge region that drives the charge carriers along the nanorods. The self-assembled ZnCdS nanoflowers provide extra channels for the charge transfer, improving the separation of electron–hole pairs.

Strongly Emissive Lead‐Free 0D Cs3Cu2I5 Perovskites Synthesized by a Room Temperature Solvent Evaporation Crystallization for Down‐Conversion Light‐Emitting Devices and Fluorescent Inks

AbstractLead‐free 0D metal halide perovskites are emerging environmentally friendly materials exhibiting large exciton binding energy, which have recently attracted great attention for their excellent light emission properties and favorable stability. Herein, solvent evaporation crystallization at room temperature is adopted to fabricate 0D Cs3Cu2I5 perovskite millimeter‐sized crystals, which show strong blue photoluminescence (PL) with quantum yield of up to 89%, a large Stockes shift and long (microsecond) PL lifetime, originating from self‐trapped excitons. UV pumped light‐emitting diodes are demonstrated by using Cs3Cu2I5 powder as a solid‐state phosphor, and the precursor solution of these perovskite crystals is used as a fluorescent ink. Furthermore, blue‐emitting composite Cs3Cu2I5/polyvinylidene fluoride films are produced by spin coating through the solvent evaporation and followed patterning using a direct laser writing technology, which are potentially useful for displays. Finally, the solvent evaporation crystallization method is expanded to fabricate yellow emissive CsCu2I3 crystals by changing the chemical molar ratio of precursor.

A study of sol gel process parameters on CoCuMnOx selective coating characteristics

This research addresses the effect of process parameters on the optical properties of solar selective coating. The proposed study discusses the deposition of a selective coating of CoCuMnOx onto stainless-steel substrate. The coating was prepared via a sol-gel route and dip coating process. Mechanical adhesion between the coating and the substrate was increased through increasing the surface roughness of the substrate. Four parameters were discussed; precursor concentration, withdrawal rate, number of coating layers and the heat treatment temperature. The best achieved absorptivity was 0.906 in the wavelength range of (200–900 nm) and emissivity was 0.116 in the wavelength range of (2.5–25 μm) for a sample with precursor molar ratio divided by 60, 1.5 cm min−1 withdrawal rate, double coating layer and 450 °C heat treatment temperature. Detailed coating characterization was discussed through XRD, EDX and SEM analysis.

Powder sintered Ni–P/CNTs composites as three-dimensional self-supported efficient electrocatalysts for hydrogen evolution reaction

Nickel phosphide can become a new generation of hydrogen evolution reaction (HER) non-precious catalyst due to the low price and abundant source. In this work, we reported the preparation of three-dimensional self-supported Ni–P/CNTs composite electrodes which adopted porous nickel powder and red phosphorus decorated with multi-walled carbon nanotubes by powder sintering. The phase, microstructure, and electrocatalytic performance of Ni–P/CNTs composite electrodes were systematically studied. The HER activity of Ni–P/CNTs composite electrodes could be affected by adjusting the molar ratio of Ni:P precursor. When the molar ratio of Ni:P was 1:1, the NiP-3 composite electrode has a better HER performance in acidic electrolyte than in alkaline electrolyte. This work indicates that the phase and micromorphology of the composite electrodes can be optimized by adjusting the Ni:P precursor molar ratio so that boosting the electrocatalytic HER performance.

Preparation of Silicophosphate Alternating Hybrid Copolymers via Nonaqueous Acid-Base Reactions of Phosphoric Acid and Organo-Bridged Bis(chlorosilane).

A design of atomic and oligomer level structure in organic-inorganic hybrid materials is highly important for various applications. Nonaqueous acid-base reaction allows us to prepare silicophosphates with controlled inorganic networks (–(O–P–O–Si)n) at atomic level because phosphorous and silicon-based precursors can react directly, resulting in an alternating copolymer network. Organic functionalization in those materials has been realized so far by using organic-modified phosphorous acid and/or organo-chlorosilane as precursors. In the present study, silicophosphate oligomers exhibiting inorganic-organic hybrid chains of (–(O–P–O–Si–R–Si)n) (R: bridging organic functional groups), are prepared from phosphoric acid and organo-bridged bis(chlorosilane). The 1, 2-bis(chlorodimethylsilyl)ethane ((C2H4)(Me2SiCl)2) and 1, 4-bis(chlorodimethylsilyl)benzene ((C6H4)(Me2SiCl)2) were used as organo-bridged bis(chlorosilane). Different types of silicophosphate oligomers with different network structures and terminal groups (P-OH and/or Si-Cl) were prepared by changing the reaction temperature and molar ratio of precursors. The formation of low molecular weight oligomers of ring and cage morphologies (ring tetramer, cage pentamer, and ring hexamer) is suggested in the product prepared from phosphoric acid and (C6H4)(Me2SiCl)2 molecule at 150 °C. Those silicophosphate hybrid oligomers are expected to be used as building blocks of hybrid materials with well-defined network structures for desired functionalities.

Formation of CdSe quantum dots from single source precursor obtained by thermal and laser treatment

The synthesis of CdSe quantum dots (QDs) from a single source precursor is a known way to form a nanocomposite by its thermal decomposition. Recently, some of them have been used to grow QDs by direct laser patterning. Here, the authors report the study of the formation of the CdSe QDs starting from the decomposition of the 2-(N,N-dimethylamino)ethylselenolate of cadmium dispersed in a polymethylmethacrylate film induced both by heating and laser patterning. The formation of the CdSe QDs under annealing at 150 °C is studied as a function of the precursor concentration and molar ratio with respect to two different QD ligands such as oleic acid and oleylamine. The photoluminescent spectra of the formed nanocomposite show that the oleic acid induces the formation of the direct bandgap, while oleylamine shows only a broadband emission. The laser patterning of the film was carried out with a UV laser (355 nm) with a pulse frequency of 40 kHz and a fluence of 1.06 J/cm2. The resulting patterned areas were characterized by a fluorescence microscope showing the formation of a photoluminescence path only when the ligands were present, suggesting the formation of the functional (photoluminescent) QDs.

Facile Preparation of Ni-Co Bimetallic Oxide/Activated Carbon Composites Using the Plasma in Liquid Process for Supercapacitor Electrode Applications.

In this study, a plasma in a liquid process (PiLP) was used to facilely precipitate bimetallic nanoparticles composed of Ni and Co elements on the surface of activated carbon. The physicochemical and electrochemical properties of the fabricated composites were evaluated to examine the potential of supercapacitors as electrode materials. Nickel and cobalt ions in the aqueous reactant solution were uniformly precipitated on the AC surface as spherical nanoparticles with a size of about 100 nm by PiLP reaction. The composition of nanoparticles was determined by the molar ratio of nickel and cobalt precursors and precipitated in the form of bimetallic oxide. The electrical conductivity and specific capacitance were increased by Ni-Co bimetallic oxide nanoparticles precipitated on the AC surface. In addition, the electrochemical performance was improved by stable cycling stability and resistance reduction and showed the best performance when the molar ratios of Ni and Co precursors were the same.

Quaternized polyhedral oligomeric silsesquioxanes stabilized Pd nanoparticles as efficient nanocatalysts for reduction reaction

Hydrophilic quaternized polyhedral oligomeric silsesquioxane (QPOSS) stabilized palladium nanoparticles hybrids (PdNPs@QPOSS) were successfully constructed for catalytic reduction of organic dyes and nitrophenols. The size of PdNPs can be effectively regulated through the molar ratio between QPOSS and Pd precursors. Uniformly dispersed nano-sized QPOSS encapsulated ultra-fine PdNPs with average diameter of 2.38 nm were obtained as the molar ratio of precursors was 1:8. It was found that low-dose PdNPs@QPOSS nanohybrids as catalysts exhibited outstanding catalytic reduction activity for methylene blue (MB) and nitrophenol (4-NP) with high conversion frequencies (TOF) of 213.7 and 17.8 min−1 respectively, which is superior to commercial Pd/C catalyst. The nanocatalysts we prepared could be stably dispersed in water for one month and there was no significant loss of catalytic activity in four catalytic cycle. The enhanced catalytic activity and good stability can be attributed to QPOSS as a stabilizer having strong coordination with as-generated PdNPs. In addition, we evaluated the decolorizing properties of common organic pollutants including methyl orange (MO), congo red (CR), methyl orange (MO), rhodamine 6G (R6G), rhodamine B (RhB), rhodamine 6G (R6G), and nitrophenol derivatives. The organic-inorganic hybrid nanocatalyst PdNPs@QPOSS is very effective in catalytic reduction of a series of colored dyes and nitrophenols, which also means that the nanohybrid as catalyst has a wide range of applications in industrial degradation of organic pollutants in wastewater.

Antibacterial activity and cytotoxicity of novel silkworm-like nisin@PEGylated MoS2

Recently, molybdenum disulfide functionalized with poly-ethylene glycol (PEGylated MoS2) has been widely used as a new drug delivery vehicle in biomedical field. However, the weak antibacterial activity of PEGylated MoS2 limits its application as an antibacterial agent. In this work, a novel silkworm-like conjugate of nisin loaded PEGylated MoS2 (nisin@PEGylated MoS2) was developed for antibacterial application. The morphology and structure of PEGylated MoS2 were strongly dependent on the Mo/S molar ratio of precursors during the solvothermal process. The silkworm-like skeleton was well kept after loading with nisin. A high level of reactive oxygen species (ROS) induced by the conjugate was an important cause of bacteria death. Due to the different structure of cell membranes, the sharp edges could more easily puncture into Escherichia coli (E. coli) as compared with Staphylococcus aureus (S. aureus) and produced more intracellular ROS, which improved the antibacterial activity of nisin against E. coli. As a result, nisin@PEGylated MoS2 displayed the antibacterial activity against both gram-positive and gram-negative bacteria. Furthermore, the toxicity of the conjugate was very low. Therefore, the target conjugate of nisin@PEGylated MoS2 may have great potential application as an antibacterial agent.

Morphological and electrical characterizations of dip coated porous TiO2 thin films with different concentrations of thiourea additives for resistive switching applications

Dip coating process was used as a synthesis technique for the fabrication of porous TiO2 thin films, where titanium (IV) n-butoxide precursor was used along with Pluronic F-127 and thiourea additives. In this research, thiourea to precursor molar ratio was varied from 0 to 10%, whereas the concentration of the F127 was kept as 3 mM. The post-synthesis structural, morphological, optical and electrical characteristics of the porous TiO2 thin films were investigated. The FESEM micrographs have shown the surface modulation with the different molar ratio of thiourea, whereas the XRD patterns have depicted the evolution of anatase phase of the TiO2 films. The capacitance–voltage measurements were carried out to study the charge densities associated with the TiO2 films. It has been revealed that the films, deposited with 8% molar ratio of thiourea, have possessed higher density of oxide and interface charges. The films, synthesized at 8% thiourea, have also shown better bipolar resistive switching properties as revealed from the current–voltage characteristics of TiO2 memristors.

Morphology and phase controlled synthesis of PVP-assisted copper antimony sulfide microstructures using solvothermal method and their properties

Shape and phase controlled synthesis of Polyvinylpyrrolidone (PVP) assisted Copper Antimony Sulfide (CAS) nano/- microstructures were successfully synthesized by solvothermal method in single step. X-ray diffraction (XRD) reveals that the orthorhombic phase of CuSbS2for different molar ratio of precursor. The Raman spectra of CAS nano/- microstructures clearly exhibit a single phase of CuSbS2. The morphology of the prepared CAS nano/- microstructures were characterized using Field emission scanning electron microscopy (FE-SEM), which showed of monodispersed CuSbS2 microstructures. The Energy Dispersive X-ray Analysis (EDAX) confirmed the presence of copper, antimony, sulfide and their atomic ratio is around 1:1:2. Using different molar ratio of precursor in solution process, phase-pure, highly crystalline CuSbS2 microstrutures with around 40 nm crystallite size was successfully obtained. The optical absorption spectra reveal that the CuSbS2 has optical bandgap varying from 1.61 eV to 1.74 eV. I–V characteristics for CuSbS2 semiconducting thin films show linear characteristics. Hall measurement studies reveal that film prepared from the sample consisting microspheres with flakes like morphology acquires low resistivity, high mobility and high carrier concentration.

An Efficient Automated Radiosynthesis and Bioactivity Confirmation of VMAT2 Tracer [18F]FP-(+)-DTBZ.

The aim of this study was to optimize the radiolabeling method of [18F]fluoropropyl-(+)-dihydrotetrabenazine ([18F]FP-(+)-DTBZ) to fulfill the demand of preclinical and clinical application. Optimized labeling conditions were performed by altering the molar ratio of precursor to base (P/B), base species, solvents, reaction temperature, reaction time, and precursor concentration through manual radiosynthesis of [18F]FP-(+)-DTBZ. The conditions with the highest radiochemical yield (RCY) were applied to automated radiosynthesis, and the crude product was purified with a Sep-Pak Plus C18 cartridge. Quality control and stability of [18F]FP-(+)-DTBZ were carried out by HPLC. In vitro cellular uptake and blocking assays were conducted in human neuroblastoma cell line SH-SY5Y. In vivo imaging with small animal positron emission tomography (microPET) was performed with Sprague-Dawley rats. Under the optimized conditions (P/K2CO3 = 1:8, heating at 120°C for 3min in dimethyl sulfoxide), an RCY of 88.7% was obtained with 1.0mg precursor. The optimized reaction conditions were successfully applied to an automated module and gave a high activity yield (AY) of 30-55% in about 40min with a > 99.0% radiochemical purity (RCP) and a > 44.4GBq/μmol molar activity (Am). Stability test displayed that the RCP retained > 98.0% in 8h in saline and in phosphate buffer saline (PBS, pH7.4). In vitro cellular uptake assay showed accumulation of [18F]FP-(+)-DTBZ in SH-SY5Y cells, which could be significantly inhibited by vesicular monoamine transporter 2 (VMAT2) inhibitor DTBZ. MicroPET images of rat brain displayed that the striatum showed the highest uptake with a standardized uptake value (SUV) of 3.91 ± 0.30 at ~ 70min. Co-injection with DTBZ (1.0mg/kg) resulted in a 75% decrease of the striatal SUV, confirming the specificity of [18F]FP-(+)-DTBZ to VMAT2. We obtained an optimized radiolabeling method of [18F]FP-(+)-DTBZ and successfully applied it to a commercial available module. The automated synthesis gave a high AY and RCP of [18F]FP-(+)-DTBZ with high and specific binding to VMAT2, facilitating its routine application for VMAT2 tracing.

Ultrasound Assisted Synthesis of Size-Controlled Aqueous Colloids for the Fabrication of Nanoporous Zirconia Membrane.

Permeation and separation efficiency of ceramic membranes are strongly dependent on their nanoporous structures, especially on the pore size. In this work, ultrasound is employed to form the size-controlled ZrO2 nanoparticles, and a ceramic membrane is prepared with tunable pore size. Under the ultrasound treatment, H+ from water plays a key role in the synthesis process. The cavitation caused by ultrasound promotes the hydrolysis of the precursor in water, which produces a large number of H+. These H+ will react with precipitant added and generate cyclic tetrameric units. Excess H+ can peptize cyclic tetrameric units and form an electrical double layer, resulting in a stable sol. Unlike ultrasound treatment, precipitant will react directly with the precursor and generate precipitation if there is no ultrasound added. Moreover, cavitation is good for the dispersion of cyclic tetrameric units. The particle size of Zr-based colloidal sol can be tuned in the ranges of 1.5 to 120 nm by altering the molar ratio of precursor to precipitant, ultrasonic power density and radiation time. Meanwhile, ultrasonic power density and radiation time have effects on grain size and the crystalline transition temperature of particles which influence performance of the ceramic membrane. As a result, membranes exhibit high performance together with high permeability and desirable rejection. To develop such a simple and controllable method for tuning particle size is extremely important in the preparation of nanoporous ceramic membranes.

Enhanced sensitivity of grain sizes to precursor stoichiometry enables high-quality CH3NH3PbI3 films for efficient perovskite solar cells

We demonstrate that the sensitivity of grain sizes to precursor CH3NH3I/PbI2 molar ratio can be promoted by hydroiodic acid additive for one-step spin-coated CH3NH3PbI3 film. Thus, the full-coverage, high-crystallinity CH3NH3PbI3 film with average grain size of ∼1.75 μm can be obtained by simply adjusting precursor molar ratio. Planar perovskite solar cell (PSC) with this desired film yields the optimized efficiency of 19.29%. Hence, our work suggests a facile precursor stoichiometry engineering through the assistance of hydroiodic acid to obtain efficient CH3NH3PbI3 PSCs.

Evaluation of Structural Properties and Catalytic Activities in Knoevenagel Condensation Reaction of Zeolitic Imidazolate Framework-8 Synthesized under Different Conditions

In the present study, the zeolitic imidazolate framework-8 (ZIF-8) was synthesized at both room temperature and high temperatures. The effects of solvents, molar ratios of precursors, reaction time, and temperature on the structural properties of the as-prepared materials were investigated. Moreover, the surface morphologies of the obtained specimens were characterized using X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and nitrogen adsorption methods. The results show that ZIF-8 was formed in methanol and water at room temperature and in dimethylformamide (DMF) at high temperatures. Further, in methanol, the molar ratios of precursors and reaction time have negligible effects on the morphologies and structures of ZIF-8; however, in DMF, the reaction temperature has a significant influence on the microstructures of ZIF-8. The catalytic activities of the obtained materials were evaluated using the Knoevenagel condensation reaction, and ZIF-8 proves to be an excellent solid base catalyst.

Gel combustion synthesis of fluorine-doped tin oxide and its characteristics: applying D-optimal factorial design of experiment

Fluorine-doped tin oxide (FTO) nano-powders were synthesized by a gel combustion method. To analyse the effect of processing factors and their interactions and to achieve an equation for nano-powder particle size in terms of code factors, D-optimal factorial design was used. Stannous chloride penta-hydride, ammonium fluoride and citric acid were used to synthesize the FTO nano-powders. The structure, morphology and composition of the synthesized powders were characterized by X-ray diffraction, field emission scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. The results revealed the formation of homogenous FTO nano-powders with an average particle size of 20 nm and equiaxed morphology in the concentration of precursor 0.2, citric acid to precursor molar ratio of 1 and pH of 0.5. The average particle size increased as the concentration of the precursor, citric acid to precursor molar ratio and pH increased from 0.2 to 1, 1 to 3 and 0.5 to 3, respectively. Citric acid to precursor molar ratio, concentration of the precursor and the pH had the most significant effect on the synthesis of the FTO nano-powders, respectively.

Facile synthesis of Cu2ZnGeS4 thin films from binary metal sulfides and study of their physical properties

In this work, we report the synthesis of Cu2ZnGeS4 (CZGS) thin films using a paste of binary metal sulfides by doctor blade technique. The precursor to deposit the films was obtained by mixing appropriate amounts of CuS, ZnS and GeS with triethanolamine and dilute acetic acid. Initially, the effect of annealing temperature on the phase formation was investigated using the films developed with the precursor containing stoichiometric ratios of metal sulfides. Based on the results obtained for structural and compositional properties of the films using the stoichiometric precursor we further proceeded with the fabrication of Cu-poor CZGS films by varying the binary sulfide concentrations in the precursor. CZGS films deposited with precursor molar ratio, CuS:ZnS:GeS = 1.6:1.2:1, resulted in [Cu]/([Zn] + [Ge]) and [Zn]/[Ge] ratios, 0.77 and 1.21, respectively. Formation of polycrystalline CZGS tetragonal structure was confirmed by X-ray diffraction and the Raman spectroscopy. Scanning electron microscopy revealed flake-like morphology along with pyramidal shaped crystals. The optical band gap of the films was around 1.8 eV. The films were photosensitive and exhibited one order increase in photoconductivity under 100 mW/cm2 illumination. The fabrication of Cu-poor CZGS films is reproducible by upscaling the amounts of binary sulfides and dispersing medium which provides an attractive option for cost-effective deposition over large area.

Construction of Ag/AgCl-CN heterojunctions with enhanced photocatalytic activities for degrading contaminants in wastewater

The non-metallic organic polymer carbon nitride has attracted widespread attentions, but its photocatalytic performance is unsatisfactory due to high recombination of photoinduced carriers. To solve this issue, we report Ag/AgCl-decorated carbon nitride (CN) nanorod heterojunctions as efficient and stable photocatalyst. CN nanorods (diameter: ∼25 nm; lengths: 1–1.5 μm) were prepared by a simple solvothermal route, and then in-situ growth of Ag/AgCl nanoparticles (diameter: 20–40 nm) on CN surface was realized by a facile co-precipitation method. Ag/AgCl-decorated CN heterojunctions with diverse Ag/CN precursor molar-ratios (0.3, 0.5, 0.7) exhibit a wide absorption spectrum from UV to visible-light region (∼750 nm). After the illumination of visible-light for 120 min, 0.5-Ag/AgCl-CN nanorods can degrade 98.5% rhodamine B (RhB), 75.4% tetracycline (TC) and 39.5% Cr(VI), obviously better than those of CN nanorods (62.6% RhB, 35.6% TC, 19.7% Cr(VI)), Ag/AgCl nanoparticles (66.5% RhB, 18.5% TC, 24.6% Cr(VI)) and Ag-CN (72.6% RhB, 39.4% TC, 28.7% Cr(VI)). This obvious improvement should result from efficient separation of photogenerated carriers. Therefore, Ag/AgCl-CN can act as an efficient and stable visible-light-driven photocatalyst.

Improvement of Cs‐(FAPbI3)0.85(MAPbBr3)0.15 Quality Via DMSO‐Molecule‐Control to Increase the Efficiency and Boost the Long‐Term Stability of 1 cm2 Sized Planar Perovskite Solar Cells

While interfacial and grain‐boundary passivation presently attract enormous research interest for perovskite solar cells (PSCs), the improvement of Cs‐(FAPbI3)X(MAPbBr3)Y bulk quality still lacks systematical study, especially for constructing polycrystalline layers in planar configurations. Here, a DMSO‐molecule‐process for improving the quality of Cs‐(FAPbI3)0.85(MAPbBr3)0.15 is developed, where the molar ratio of precursors, the kind of anti‐solvents, and speed‐time profiles are found critical. The optimized treatment significantly enhanced the crystal orientation, grain size, surface roughness, photo‐response, carrier lifetime, and contact potential difference of absorbers. Cs‐(FAPbI3)0.85(MAPbBr3)0.15 absorbers also present superior charge transport, as well as reduced carrier recombination and decreased trap densities via DMSO‐molecule‐control, enabling performance improvement on both long‐term stability and photovoltaic parameters of 1 cm2 PSCs. Champion planar cells demonstrated a power conversion efficiency (PCE) of 21.07% (0.159 cm2) and PCE of 19.4% (1 cm2) with negligible hysteresis. Moreover, 1 cm2 devices retained 90% of initial PCE after aging 50 days in ambient air.