Pb Sn Research Articles

Resolving Mixed Intermediate Phases in Methylammonium-Free Sn–Pb Alloyed Perovskites for High-Performance Solar Cells

HighlightsThe first study dedicated to solving the problem of mixed intermediate phases in methylammonium (MA)-free (FA-Cs) Sn–Pb alloyed perovskite systems, new performance records of 21.61% and 23.82% realized for its single-junction and tandem devices.d-Homoserine lactone hydrochloride (D-HLH), employed as an additive, accelerates the transition from mixed intermediate phases into preformed perovskite nuclei.The presence of D-HLH eliminated the negative effect of mixed intermediate phases and regulated the crystallization kinetics.

Carbonyl functional group assisted crystallization of mixed tin–lead narrow bandgap perovskite absorber in ambient conditions

Tin–lead (Sn–Pb) perovskite solar cells are receiving growing interest due to their applications in tandems and lead mitigation. Nonetheless, fast crystallization and facile Sn2+ oxidation restrict their ambient fabrication, which increases fabrication costs. This Letter presents an experimental study on additive assisted growth of FA0.2MA0.8Sn0.5Pb0.5I2.4Br0.6 narrow bandgap perovskite films employing a Lewis-base molecule, caffeine (1,3,7-trimethylpurine-2,6-dione), having two carbonyl functional groups (C = O) in ambient conditions (relative humidity < ∼10%). The C = O interacts with metallic ions (Sn2+ and Pb2+) via chelation to form an acid–base adduct, slowing down the fast crystallization of FA0.2MA0.8Sn0.5Pb0.5I2.4Br0.6 perovskite films. As a result, the grain size improves resulting in better structural and optical properties. In contrast, Urbach energy values showed higher electronic disorder near the band edges even upon caffeine doping implying Sn4+ doping in an ambient environment. This work accentuates the potential of the acid–base adduction to regulate uncontrolled crystallization of Sn–Pb perovskites in the ambient environment.

Fluid evolution and ore genesis of Cu–Pb–Zn veins in the Panjiaduan deposit, Great Xing’an Range, NE China: evidence from fluid inclusion and H–O–He–Ar isotopes

AbstractThe southern Great Xing’an Range (SGXR), located in the eastern segment of the Central Asian Orogenic Belt (CAOB), is one of the most economically important Cu–Mo–Fe–Sn–Pb–Zn–Ag metallogenic provinces in China. The newly discovered Panjiaduan Cu–Pb–Zn deposit (9.3 Mt; at 1.36% Cu, 2.90% Pb, 3.80% Zn and 38.12 g/t Ag), located in the SE segment of the SGXR, is primarily hosted in fracture zones in volcanic rocks and granodiorite of the Manitu Formation. Four paragenetic stages of metallic mineralization are identified: (I) quartz-pyrite-arsenopyrite; (II) quartz-polymetallic sulphide; (III) quartz-galena-sphalerite-argentite; and (IV) quartz-calcite-minor sulphide. The hydrothermal quartz contains three types of primary fluid inclusion (FIs): vapour-rich two-phase liquid-vapour (LV-type), liquid-rich two-phase liquid-vapour (VL-type) and three-phase liquid-vapour-solid FIs (SL-type). Stages I and II contain all types with homogenization temperatures (Th) of 324–386 °C and 276–334 °C as well as salinities of 0.7–38.0 wt% and 0.9–34.7 wt%, respectively, whereas stage III is composed of VL- and LV-type FIs with Th of 210–269 °C and salinities of 0.5–7.2 wt%. Only VL-type FIs occur in stage IV, with Th of 139–185 °C and salinities of 1.6–4.2 wt%. The δ18OH2O and δD values vary from −15.7 to 2.6‰ and −132.7 to −110.2‰, respectively, indicating predominant meteoric water with an initial magmatic source. The He–Ar isotopic compositions of the pyrite inclusions from the Panjiaduan Cu–Pb–Zn veins suggest that fluids were derived from the crust.

Constructing the deep-spreading pattern of tectono-geochemical anomalies and its implications on the Huangshaping W–Sn–Pb–Zn polymetallic deposit in southern Hunan, China

Huangshaping large W–Mo–Pb–Zn polymetallic deposit is a typical representative of the Cu–Sn metallogenic system in Nanling Range, South China. This deposit located in the superimposed tectonic setting of the Qinzhou–Hangzhou and Nanling metallogenic belts. Skarn-type W–Sn orebodies and hydrothermal vein-type Pb–Zn–Cu orebodies located in the faults and contact zone between late Jurassic porphyry and late Paleozoic limestone. Many studies have been conducted on the geological and geochemical characteristics of the deposit, but the comprehensive understanding of the deep-spreading pattern of the tectono-geochemical anomalies remains unclear. The geochemical data of tectonites in deep level adits (−136 m, −176 m, −256 m and −296 m) were studied the distribution characteristics of ore-forming trace elements and the depth index of tectonic geochemical anomalies. Finally, four element combination anomalies were extrated from the cluster analysis and factor analysis. They are generally consistent with the known Cu–Pb–Zn and W–Sn–Mo–Bi metallogenic systems. In addition, from altered porphyry to limestone of the Shidengzi Formation, the plane and profile anomaly contour maps delineated by different factors have regular variation characteristics. High anomalous values usually occur in the part where ore-forming porphyry changes from convex to concave. Comprehensive study trace element combination anomalies shows that the connection line of high value anomalous zones corresponds to the swelling and shrinking characteristics of porphyry, showing periodic wave-like changes. Thus, the deep index and deep-spreading pattern of ore-controlling structure were constructed. The length, width and height of the deep-seated orebodies indicated by the main anomalies are evaluated. The anomalous vertical variation indicates the migration of ore-forming fluid from SE to NW to the shallow. The strike of orebodiesy are consistent with the ore-controlling faults and dip to SE. Overall, the tectonic geochemical anomalies are consistent with the locations where the orebodies were identified, indicating that the method is feasible and effective. This study has an important significance for the layout of deep-prospecting and exploration projects in the Huangshaping deposit and even in southern Hunan.

Metal-cation-mixed lead-less two-dimensional hybrid perovskites with high carrier mobility and promoted light adsorption

The metal cation mixing in hybrid perovskite has been suggested as an effective strategy not only to promote the performance and stability but also to reduce the content of toxic lead element for environmental and health concerns. However, such a strategy has yet been well demonstrated in two-dimensional (2D) hybrid perovskites with multilayered thickness (n > 1). Here, we theoretically investigated the lead-less and lead-free 2D hybrid perovskites with tin-lead (Sn–Pb) and germanium-tin (Ge–Sn) mixed metal cations, namely, the BA2MAn-1Snn/2Pbn/2I3n+1 and BA2MAn-1Gen/2Snn/2I3n+1 (BA: C4H9NH3+; n = 1–4), by means of first-principle calculations. It is found that the electronic structure and light absorption properties of the 2D hybrid perovskites can be efficiently tuned to the optimal range for solar cells by combining the metal cations mixing and the layer thickness (n) adjustment. Markedly, due to the enhanced in-plane elastic modulus but greatly reduced deformation potential constant, both the Ge–Sn and Sn–Pb mixed 2D perovskites show high carrier mobility (∼103−104 cm2V–1S−1), which are superior to that of their 3D analogues. Moreover, the Sn–Pb mixed 2D perovskites expose much stronger visible light absorption than the non-mixed Sn- or Pb-based 2D perovskites. In addition, the in-air stability of metal-cation-mixed 2D hybrid perovskites are greatly improved compared to the 3D halide perovskites. This work suggests the great potential of the metal-cation-mixed 2D hybrid perovskite for photovoltaic and optoelectronic applications with largely reduced lead content.

Investigation of carrier transport behavior for cubic CH3NH3SnX3 and CH3NH3PbX3 (X=Br and I) using Boltzmann transport equation

As a novel semiconductor, hybrid halide perovskites become candidate materials for the next generation of solar cells due to their high conversion efficiency and low processing cost. In the face of the uncertainty of electric transport properties in experimental measurement, it is necessary to predict the upper limit of mobility that they theoretically achieve. In this work, a new approach is adopted to improve the computational efficiency. Phonon-limited mobility for CH3NH3SnX3 and CH3NH3PbX3 (X=Br and I) is successfully predicted by ab initio Boltzmann transport equation (BTE) including all electron–phonon interactions (EPI). The convergent values for high frequency dielectric constant and Born effective charge are first obtained with moderate k grids of 16×16×16, and then they are substituted into the program. Subsequently, EPI matrix element is obtained by density functional perturbation theory (DFPT) with coarse 4×4×4k/q grids. To correct the shape of the band edge, the spin–orbit coupling (SOC) effect is included in the calculation. We reveal that longitudinal optical (LO) phonons associated with the stretching of Pb(Sn)-I(Br) atoms limit carrier mobility. CH3NH3SnI3 exhibits higher mobility than other materials. Its drift mobility is as high as μe=403∼559 and μh=1558∼1734cm2V−1s−1. Furthermore, Hall factor is investigated by analyzing the average relaxation time, and Hall mobility is predicted to be μe=432∼598 and μh=1725∼1920cm2V−1s−1. Compared with other typical semiconductors, CH3NH3SnI3 exhibits high hole mobility.

Carrier control in Sn–Pb perovskites via 2D cation engineering for all-perovskite tandem solar cells with improved efficiency and stability

Carrier control in Sn–Pb perovskites via 2D cation engineering for all-perovskite tandem solar cells with improved efficiency and stability

Dual Organic Spacer Cation Quasi‐2D Sn–Pb Perovskite for Solar Cells and Near‐Infrared Photodetectors Application

Tin (Sn)‐ and Sn–Pb‐based perovskites arouse great interests in low‐toxicity perovskite. Nevertheless, the instability problems that aroused by Sn oxidation still hinder their applications. To improve the stability of Sn‐based perovskite, a relative stable quasi‐2D Sn–Pb perovskite is proposed by introducing two mixed organic cations, 2‐phenylethylammonium (PEA+), and butylammonium (BA+), which facilitate both precursor assembly and carrier transportation. As a result, efficient and stable quasi‐2D Sn–Pb perovskite solar cells (PSCs) with a power conversion efficiency (PCE) of ≈10% and an improved open‐circuit voltage (Voc) of 0.808 V under AM 1.5G illumination are achieved. The maximum power point (MPP) shows that the current of quasi‐2D Sn–Pb PSC still maintains 97.7% of original value after 20 000 s. Furthermore, the application of the mixed spacer cation quasi‐2D Sn–Pb perovskite in near‐infrared (NIR) light detection is demonstrated. Herein, the quasi‐2D Sn–Pb perovskite shows a high detectivity of ≈6.57 × 1011 Jones with n–i–p structure under 850 nm. It is suggested in the results that the quasi‐2D Sn–Pb perovskite with improved stability holds great potential in infrared photodetection and imaging application.

Alkyl Diamine-Induced (100)-Preferred Crystal Orientation for Efficient Pb–Sn Perovskite Solar Cells

The narrow band gap lead–tin (Pb–Sn) perovskite is a promising light absorption layer for highly efficient perovskite solar cells (PSCs), particularly for tandem applications. However, its random crystal orientation dramatically limits its power conversion efficiency (PCE). Here, a propane diamine bromide (PDABr) additive is developed to effectively modulate the Pb–Sn perovskite to grow along the (100)-preferred orientation. It is found that the PDA cations naturally anchor onto the colloidal perovskite nucleus to serve as a surface template to modulate the perovskite crystal to grow preferentially along its (100) orientation, while the bromide ions aid in increasing the grain size, resulting in a densely packed film with significantly reduced density of grain boundaries. As a result, the PDABr-based film exhibits increased carrier mobility and reduced defect density. With these merits, the PDABr-based Pb–Sn PSCs demonstrated an impressive PCE of 20.41%, which is much higher than that of the control device (16.23%). This work provides a general approach to realize the preferred crystal growth for Pb–Sn perovskite films to attain high optoelectronic performance.

What happens when a Pb–Sn coating deposited on low carbon steel is exposed in an HCl‐polluted wet environment? Development of a corrosion mechanism

AbstractThis article synthesizes all the results obtained to establish a global corrosion mechanism when a Pb–Sn coating deposited on low carbon steel is corroded in an HCl‐polluted wet environment. The successive stages of the process are shown. In HCl‐polluted environment, coupled with water, acid chlorides provide an aggressive electrolyte particularly favorable to corrosion. In contact with this electrolyte, lead products are created as PbCO3 and PbCl2, showing the impact of the surrounding atmosphere. In parallel, the electrolyte concentrates in Sn2+ until saturation, and tin precipitates under different forms. Due to the lead consumption, the lead corrosion products layer breaks, and the coating thins, diffusion pathways are created and the steel oxidizes. Iron corrosion products are similar with or without a coating except for the presence of a tin‐rich filament. Lead is no longer present. The different stages of the mechanism are compared to corrosion phenomena observed during the use of Pb–Sn alloys to provide effective solutions to minimize or even avoid the phenomenon of corrosion.

Anthropocene Geochemical and Technological Signatures of an Experimental Landfill Bioreactor in the Central Valley of California

The geochemical signatures of a 12-year-old experimental bioreactor at a California landfill are used to identify elemental concentrations and ratios that characterize the landfill and relate it to the age and state of technology of the deposited waste. The bioreactor was constructed and sealed with a synthetic liner during 2001–2002 and operated and monitored as an anaerobic digester to enhance methane production. In 2013, the bioreactor was sampled and trace element concentrations of the extracted fine fractions were determined. The concentrations normalized to a regional soil composition, reveal systematic peaks for transition metals, alkali metals, heavy metals, and various metalloids and non-metals. A group of potential solder elements (Cu, Zn, Cd, In, Sn, Pb, Bi, and Sb) shows moderate to strong co-variations and is largely attributed to household electronic components and other similar products, while elements that correlated well with rare-earth and other elements are related to the diluting effect of a soil component used as cover. Batteries show modest to little effects on the overall concentrations. Circulating fluids (recycled leachate) in the controlled reactor did not completely redistribute and homogenize the elemental signatures within the time frame of the bioreactor. It is concluded that the present experimental landfill defines an Anthropocene marker identifiable by building material (plaster), PVC plastic, and household electronic components (Pb–Sn solder). These marker elements and ratios are variably diluted by soil components identified by alkali metals, rare-earths, and high field-strength elements (Hf, Zr, Nb, and Ta).

Enhanced Thermoelectric Properties of Te Doped Polycrystalline Sn0.94Pb0.01Se.

Thermoelectric materials can directly convert heat and electricity, which is a kind of promising energy material. In view of cost and mechanical properties, polycrystalline SnSe material with high zT value is greatly desired. In this study, polycrystalline Sn0.94Pb0.01Se1-xTex samples were prepared by the vacuum melting–hot pressing sintering method. Sn vacancies, Pb and Te atoms were simultaneously introduced into the polycrystalline SnSe. The power factor of Sn0.94Pb0.01Se1-xTex samples was decreased, which could be attributed to the generation of n-type semiconductor SnSe2. In addition, the phonons were strongly scattered by point defects and dislocations, which led to the decrease of thermal conductivity—from 0.43 Wm−1K−1 to 0.29 Wm−1K−1 at 750 K. Finally, the polycrystalline Sn0.94Pb0.01Se0.96Te0.04 sample achieved the maximum zT value of 0.60 at 750 K.

Compositional Variation in FAPb1-xSnxI3 and Its Impact on the Electronic Structure: A Combined Density Functional Theory and Experimental Study.

Given their comparatively narrow band gap, mixed Pb–Sn iodide perovskites are interesting candidates for bottom cells in all-perovskite tandems or single junction solar cells, and their luminescence around 900 nm offers great potential for near-infrared optoelectronics. Here, we investigate mixed FAPb1–xSnxI3 offering the first accurate determination of the crystal structure over a temperature range from 293 to 100 K. We demonstrate that all compositions exhibit a cubic structure at room temperature and undergo at least two transitions to lower symmetry tetragonal phases upon cooling. Using density functional theory (DFT) calculations based on these structures, we subsequently reveal that the main impact on the band gap bowing is the different energy of the s and p orbital levels derived from Pb and Sn. In addition, this energy mismatch results in strongly composition-dependent luminescence characteristics. Whereas neat and Sn-rich compounds exhibit bright and narrow emission with a clean band gap, Sn-poor compounds intrinsically suffer from increased carrier recombination mediated by in-gap states, as evidenced by the appearance of pronounced low-energy photoluminescence upon cooling. This study is the first to link experimentally determined structures of FAPb1–xSnxI3 with the electronic properties, and we demonstrate that optoelectronic applications based on Pb–Sn iodide compounds should employ Sn-rich compositions.

4‐Hydrazinobenzoic‐Acid Antioxidant for High‐Efficiency Sn–Pb Alloyed Perovskite Solar Cells

Partial tin replacement of lead is expected to be an effective means to fine‐tune the bandgap of Sn–Pb alloyed lead‐halide perovskite to harvest near‐infrared light and thus further increase the efficiency of solar cells based on it, in particular for use as a bottom component cell in the tandem cell design to break through the theoretical Shockley–Queisser (S–Q) limit of the single‐junction solar cells. However, the efficiency of Sn–Pb alloyed perovskite solar cells (PSCs) is still lower than expected owing to the easy oxidation of Sn2+. Herein, a reducing agent 4‐hydrazinobenzoic acid is developed as an additive to suppress the oxidation of Sn2+ and, meanwhile, passivate surface defects. It is found that the optoelectronic performance of Sn–Pb alloyed perovskites is improved as evidenced by the mitigated trap state density and suppressed nonradiative recombination. As a result, the Sn–Pb alloyed PSC efficiency is increased to 21.09%, one of the highest for cells with this bandgap. It is expected that this method is applicable for general Sn–Pb‐based perovskite optoelectronics.

Effect of Various Parameters on the Shear Strength of Solid-State Nanoporous Cu Bonding in Cu–Cu Disks for Power Device Packaging

Nanoparticle sintering is considered a promising alternative bonding method to Pb-based soldering for the attachment of components in high-temperature electronic devices. However, the technology still poses certain challenges, such as the difficulty in controlling the joint thickness and the generation of voids owing to solvent evaporation. In this study, a solid-state (solvent-free), nanoporous-Cu (NPC) bonding method was examined. The purpose of this study was to find the effect of the bonding temperature (200–400°C) and atmosphere (N2 or formic acid) on the shear strength of the joints formed between the NPC sheets and bare Cu disks for the replacement of the Pb–5Sn solder joint for high-temperature applications (> 300°C). The NPC/Cu joints were investigated by scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. It was shown that the bondability of NPC under a N2 atmosphere is closely related to the oxide layer formed on the NPC surface that impairs the diffusion of Cu atoms between the NPC and Cu substrate. Furthermore, the densification of the NPC microstructure under a formic acid atmosphere at ≥ 350°C owing to the rapid diffusion of Cu atoms and accompanying plastic deformation induced by surface stress enhances the shear strength of the resulting NPC/Cu joint. The shear strength of the NPC/Cu joints formed under a formic acid atmosphere increased from 14.1 MPa to 35.9 MPa with an increasing bonding temperature. These results suggest that the NPC/Cu joints are a good alternative to Pb–5Sn solder joints. Based on the results of the investigation, a mechanism was proposed to explain the superiority of the Cu–Cu joints achieved using this method.

Using Ligand Engineering to Produce Efficient and Stable Pb-Sn Perovskite Solar Cells with Antioxidative 2D Capping Layers.

Pb-Sn binary halide perovskites are a promising photovoltaic material due to their low toxicity and optical absorption spectrum well matched to the solar spectrum. However, the ready oxidation of Sn2+ to Sn4+ makes the material system currently too unstable to commercialize. Herein, ligand engineering based on antioxidative tyramine (hydrochloride, TACl) is presented for the first time to increase the stability of this material system. Using this strategy, we generate a two-dimensional (2D) capping layer on top of a standard three-dimensional Pb-Sn film. After capping, the surface defects can be passivated and the TACl-based 2D perovskite effectively protected Sn2+ from oxidation, which stabilized the Sn-Pb perovskite composition, avoiding the Pb-based perovskite formation. It is further found that the TACl treatment suppressed the halide segregation and improved the perovskite film photostability. Cell efficiency increases from 16.25 to 18.28% and device lifetime (T80) increases from less than 100 to over 1000 h. Our finding suggests that tuning ligand form/function represents a potentially highly productive direction to explore when trying to produce stable tin-based perovskite devices.

Electrodeposition of lead and lead-tin alloy on copper using an eco-friendly methanesulfonate plating bath

Lead coatings were deposited from an electroplating bath contained mainly a lead salt and free methane sulfonic acid (MSA). Electroplating copper samples with a lead-tin alloy was carried out from a plating bath contained a lead salt, a tin salt and free MSA. An organic additive was added to enhance the surface morphology and therefore the appearance of the coated samples. The parameters affected the coating quality like the plating time, current density, temperature and bath composition are optimized. Surface characterization (FE-SEM & EDX) of the formed coating shows a compact dense layer of Pb or Pb–Sn alloy. XRD of Pb–Sn coating shows clear peaks of each lead and tin. The electrochemical properties of the coated samples was investigated using the electrochemical impedance spectroscopy (EIS). The obtained coatings were compared with those obtained using the fluoroborate bath. It is worthy to mention that the presence of the organic additives markedly improved the quality of the lead coating obtained from the methanesulfonate bath so as to have the same quality of the coating obtained from the fluoroborate bath.

Gradient Doping in Sn-Pb Perovskites by Barium Ions for Efficient Single-Junction and Tandem Solar Cells.

Narrow-bandgap (NBG) tin (Sn)-lead (Pb) perovskites generally have a high density of unintentional p-type self-doping, which reduces the charge-carrier lifetimes, diffusion lengths, and device efficiencies. Here, ap-nhomojunction across the Sn-Pb perovskite is demonstrated, which results from a gradient doping by barium ions (Ba2+ ). It is reported that 0.1mol% Ba2+ can effectively compensate the p-doping of Sn-Pb perovskites or even turns it to n-type without changing its bandgap. Ba2+ cations are found to stay at the interstitial sites and work as shallow electron donor. In addition, Ba2+ cations show a unique heterogeneous distribution in perovskite film. Most of the barium ions stay in the top 600nm region of the perovskite films and turn it into weakly n-type, while the bottom portion of the film remains as p-type. The gradient doping forms a homojunction from top to bottom of the perovskite films with a built-in field that facilitates extraction of photogenerated carriers, resulting in an increased carrier extraction length. This strategy enhances the efficiency of Sn-Pb perovskite single-junction solar cells to over 21.0% and boosts the efficiencies of monolithic perovskite-perovskite tandem solar cells to 25.3% and 24.1%, for active areas of 5.9mm2 and 0.94cm2 , respectively.

Hybrid Halide Perovskite‐Based Near‐Infrared Photodetectors and Imaging Arrays

AbstractHybrid halide perovskites have been demonstrated to be prospective materials in optoelectronic devices due to their outstanding photoelectric properties and facile manufacturability by low‐cost and fast solution‐processed methods. Particularly, to meet increasingly potential applications in near‐infrared (NIR) detection and imaging, perovskites have been introduced and explored their roles, some of which achieve the comparable performance with traditional silicon counterparts. Here, the recent advancements of hybrid halide perovskite‐based NIR photodetectors and imaging arrays in terms of perovskite formation, device structures, working mechanisms, and device performances are reviewed. Pb perovskite‐based devices either employ sub‐bandgap absorption and intraband transition, or incorporate with narrow‐bandgap semiconductors to achieve NIR detection, which could reach the spectral response onset at 2.6 µm wavelength. Sn perovskite‐based devices employ the strategies of template‐assisted engineering and reducing additives to inhibit the oxidation of Sn2+ states for efficient detection. SnPb mixed perovskite devices employ compositional engineering, passivation strategies, crystallization tuning, and encapsulation to achieve efficient and long shelf‐life photodetectors with an external quantum efficiency of 70% at 940 nm wavelength. Finally, potential prospects are proposed, including spectral response extension, pixel integration, flexible devices, and stability, to advance perovskite‐based NIR detection and imaging toward commercial applications.

Leaded or unleaded? Homemade microscale tin electroplating

Abstract Social distancing measures due to the SARS-CoV-2 virus have profoundly challenged the educational experimental work. We have sought to remediate this issue by designing a series of low cost, low risk, quick, and qualitative electrochemistry and corrosion experiments to be performed in the student’s homes at the microscale with a kit provided by the teacher. One such experience is the electroplating of Sn from an aqueous chloride solution using readily available soldering wires (e.g., Sn–Pb alloy, or Sn–Ag–Cu alloy). This process catches students’ attention due to its simplicity and variety of possible applications that include corrosion protection, fabrication of electronic components, plating of cooking utensils, lithium batteries, etc.