Perovskite solar cells (PSCs) have recently demonstrated high efficiencies of over 22%, but the thermal stability is still a major challenge for commercialization. In this work, the thermal ...degradation process of the inverted structured PSCs induced by the silver electrode is thoroughly investigated. Elemental depth profiles indicate that iodide and methylammonium ions diffuse through the electron‐trasnporting layer and accumulate at the Ag inner surface. The driving force of forming AgI then facilitates the ions extraction. Variations on the morphology and current mapping of the MAPbI3 thin films upon thermal treatment reveal that the loss of ions occurs at the grain boundaries and leads to the reconstruction of grain domains. Consequently, the deteriorated MAPbI3 thin film, the poor electron extraction, and the generation of AgI barrier result in the degradation of efficiencies. These direct evidences provide in‐depth understanding of the effect of thermal stress on the devices, offering both experimental support and theoretical guidance for the improvement on the thermal stability of the inverted PSCs.
Silver‐electrode‐induced thermal degradation of the inverted perovskite solar cells is investigated with direct evidences. The diffusion of iodide and methylamine ions is directly observed in the elemental depth profile during thermal treatment only when the Ag electrode is introduced. The loss of ions leads to the reconstruction of the grain boundaries and forming thick PbI2 gaps between crystal grains.
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•HOPG as a model system to compare the effects induced by Arn+ and Cs+ ion beams employed as etching sources.•Monoatomic Cs+ beam used at very low energy values alters the HOPG ...structure to a lower extent than Ar-GCIBs.•Ar-GCIBs strongly modify the graphite basal plane and buried layers.•HOPG crystals sputtered with Cs+ show the formation GOx, together with hydrogen and cesium adducts.
Intercalation mechanisms and diffusion or segregation phenomena in graphitic materials play a crucial role in different applied science fields. The investigation of such phenomena is usually accomplished through depth profiling experiments. Ar-GCIBs (Argon- Gas Cluster Ion Beams) are commonly adopted for in-depth concentration profiling of organic or soft materials; on the other hand, cesium ions are in general more suitable for the sputtering of inorganics. During such experiments, the beam-target interaction could alter chemistry and structure of the material. In this work, we define the optimal conditions in terms of both sputtering ion source and energy to preserve the crystal features. HOPG was used as a model system to compare morphological, physical, and chemical effects induced by different Arn+ clusters, and ultra-low energy Cs+ beam during ToF-SIMS (Time of Flight Secondary Ion Mass Spectrometry) depth profiling experiments. We demonstrated, through in-situ AFM (Atomic Force Microscopy) analysis, that the monoatomic Cs+ beam alters to a lower extent the HOPG structure. On the contrary, Ar-GCIBs strongly modify the graphite surface basal plane and underlying layers. However, HOPG crystals treated with the cesium monoatomic source undergo a chemistry modification leading to the formation of graphite oxide (GOx) together with the presence of hydrogen, and cesium adducts.
Three‐dimensional host structures with superior sodiophilicity and low nucleation barriers can help combat the complex failure modes of Na metal anodes originating from accelerated dendrite ...formation, anodic corrosion, and electrolyte depletion. This work reports the fabrication of a unique super‐sodiophilic, defect‐rich and hierarchically porous skeletal carbon nanofiber (SCNF) host for SCNF@Na anodes using electrospinning of the low‐cost, renewable lignin biopolymer. The uniform nucleation and plating of Na effectuated by the hierarchically porous structure coupled with the defect‐induced formation of a resilient, F‐rich solid electrolyte interface (SEI) layer offers excellent protection to the metallic anode. The defect‐rich porous structure plays an important role in mediating dense Na nucleation, planar growth, and electrochemical stability according to the depth profiling experiments and density functional theory calculations. The SCNF@Na composite anode maintains high Coulombic efficiencies (CEs) and electrochemical reversibility in asymmetric and symmetric cells. The full cells prepared by interfacing the SCNF@Na anode with a Na3V2(PO4)2F3 cathode delivers exceptional capacity retention of 106 mAh g–1 for 350 cycles with an average CE of 99.2% at 1C, and 103 mAh g–1 after 200 cycles at 4C. Such rationally designed carbon hosts derived from biopolymers open a new avenue for safe and low‐cost metal batteries.
A novel, lignin‐derived skeletal carbon nanofiber (SCNF) host with a hierarchically porous structure is proposed for high‐rate sodium metal batteries. Its large defect‐rich surface area enables dense Na nucleation and lateral plating while concurrently catalyzing the formation of a NaF‐rich solid electrolyte interface (SEI) layer for the protection and electrochemical reversibility. The SCNF@Na composite anode interfaced with a Na3V2(PO4)2F3 cathode offers an exceptional rate capability and capacity retention in full cells.
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•We have developed a new 40kV gas cluster ion beam (GCIB) for ToF-SIMS analysis.•The increased energy showed a predicted increase in sputter rate.•No additional damage with increased ...energy was observed on Irganox test samples.•A substantial increase in signal from intact lipid molecules in mouse brain was observed.•Ar4000 clusters produced images of a hair sample with 2μm resolution.
There is considerable excitement surrounding the application of gas cluster ion beams (GCIBs) for SIMS analysis in order to study organic materials and biological samples such as cells and tissues. These ion beams, that often comprise several thousand argon atoms in the primary ion, have been used mainly for the etching of organic materials to remove damage from the surface allowing molecular depth profiling experiments to be performed. The energy of the ion beam is normally 2–20keV. There have been relatively few studies reported on the use of GCIB as analysis beams, due to difficulties related to fast pulsing and focusing of the beam along with the sometimes low ionisation efficiency. In this study, we report on the use of a new higher energy (40keV) GCIB operated in a continuous mode. When compared to lower energies depth profiles on thin films of Irganox 1010 show an increase in sputter yield while fragmentation, damage accumulation and ionisation efficiency remains unchanged. Experiments on brain tissues show increased signal levels especially for higher mass secondary ions (m/z 500+) in comparison to C60+ at 40keV and Ar4000+ at 20keV impact energy. The use of higher energies facilitates better focusing of the primary ion beam as demonstrated here on a human hair sample where we achieve a spatial resolution of <3μm. Even with this small spot size, we can detect enough signal from and high mass species for clear localisation. All results indicate that higher energies are beneficial for most aspects of ToF-SIMS applications in biology.
ToF-SIMS imaging with argon cluster sputter depth profiling has provided detailed insight into the three-dimensional (3D) chemical composition of a series of polymer multilayer structures. Depths of ...more than 15 μm were profiled in these samples while maintaining uniform sputter rates. The 3D chemical images provide information regarding the structure of the multilayer systems that could be used to inform future systems manufacturing and development. This also includes measuring the layer homogeneity, thickness, and interface widths. The systems analyzed were spin-cast multilayers comprising alternating polystyrene (PS) and polyvinylpyrrolidone (PVP) layers. These included samples where the PVP and PS layer thickness values were kept constant throughout and samples where the layer thickness was varied as a function of depth in the multilayer. The depth profile data obtained was observed to be superior to that obtained for the same materials using alternative ion sources such as C60 n+. The data closely reflected the “as manufactured” sample specification, exhibiting good agreement with ellipsometry measurements of layer thickness, while also maintaining secondary ion intensities throughout the profiling regime. The unprecedented quality of the data allowed a detailed analysis of the chemical structure of these systems, revealing some minor imperfections within the polymer layers and demonstrating the enhanced capabilities of the argon cluster depth profiling technique.
This paper presents a systematic study of the influence of electron‐transport materials on the operation stability of the inverted perovskite solar cells under both laboratory indoor and the natural ...outdoor conditions in the Negev desert. It is shown that all devices incorporating a Phenyl C61 Butyric Acid Methyl ester (60PCBM) layer undergo rapid degradation under illumination without exposure to oxygen and moisture. Time‐of‐flight secondary ion mass spectrometry depth profiling reveals that volatile products from the decomposition of methylammonium lead iodide (MAPbI3) films diffuse through the 60PCBM layer, go all the way toward the top metal electrode, and induce its severe corrosion with the formation of an interfacial AgI layer. On the contrary, alternative electron‐transport material based on the perylendiimide derivative provides good isolation for the MAPbI3 films preventing their decomposition and resulting in significantly improved device operation stability. The obtained results strongly suggest that the current approach to design inverted perovskite solar cells should evolve with respect to the replacement of the commonly used fullerene‐based electron‐transport layers with other types of materials (e.g., functionalized perylene diimides). It is believed that these findings pave a way toward substantial improvements in the stability of the perovskite solar cells, which are essential for successful commercialization of this photovoltaic technology.
Diffusion of CH3NH3I and other volatile products of photodegradation of CH3NH3PbI3 into the 60PCBM electron‐transport layer represents the key failure mechanism of inverted hybrid perovskite solar cells.
A photoconjugation strategy based on light‐triggered Diels–Alder addition of o‐quinodimethanes is compatible with biomolecules and proceeds rapidly at ambient temperature without the need of a ...catalyst. Spatial control was confirmed by photopatterning of a small‐molecule ATRP initiator, a polymer, and a peptide in a time‐of‐flight secondary‐ion mass spectrometry investigation.
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•The corrosion inhibition effect was proved after a short and long immersion time.•Tandem ToF-SIMS analyses demonstrated coverage and 3D distribution of MBTH on Zn.•GCIB sputtering ...and XPS analysis showed the formation of MBTH-Zn complexes on Zn.•Dielectric functions of the film optical phases were determined from the in situ SE.•ZnO and Zn-MBTH growth kinetics were determined from the time-resolved in situ SE.
This work describes the surface analytical characterization of 2-mercaptobenzothiazole (MBTH), which is considered to be a corrosion inhibitor for zinc and was adsorbed on the surface from 3 wt% NaCl. First, tandem (MS/MS) time-of-flight secondary ion mass spectrometry (ToF-SIMS) was employed to determine the signal that corresponds to the parent ion MBTH molecule in negative and positive polarities. The properties of the MBTH surface layer were investigated by gas cluster ion beam (GCIB) sputtering associated with X-ray photoelectron spectroscopy (XPS) and ToF-SIMS measurements. The optical functions and thickness of the films forming were determined by the time-resolved in situ spectroscopic ellipsometry, revealing the growth mechanism of the adorbates.
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Lead(II)–benzohydroxamic acid (Pb–BHA) complex collectors perform well with respect to scheelite flotation, and, due to their structure, they are widely used for industrial purposes. ...This paper examines the controversial issue of whether “O, O” five-membered ring or “N, O” four-membered ring complexes are formed when BHA coordinates with Pb ions, with their structure being comprehensively studied from the aspect of colloid and interface science. The configurations of Pb–BHA complexes are examined in a solution and on a mineral surface with experimental and computational methods. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) revealed that the five-membered ring is the dominant form of Pb–BHA complexes in a solution, whereas four-membered ring complexes are the stronger electron acceptor of the two. Moreover, XPS and time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed that the four-membered ring complexes are stable with respect to being adsorbed on the scheelite surface. Therefore, although the four-membered ring is not as stable as the five-membered ring in a solution, it offers advantages with respect to adsorption on an electron-rich mineral surface during short-flotation processes.
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