Young K-Ar gae of jarosite in the Mojave sample at Gale Crater, Mars.

By combining the Sample Analysis at Mars (SAM) instrument’s capabilities with those of the alpha particle X-ray spectrometer (APXS) on the Curiosity rover, radiometric K-Ar ages and 3He, 21Ne, and 36Ar exposure ages have been measured on two samples as of sol 1430. The Cumberland mudstone was found to have a K-Ar age of 4.21 ± 0.35 Ga (all uncertainties here are reported in 1σ), consistent with crater-counting estimates of the surrounding terrains. A second geochronology experiment was undertaken on the potassium-rich Windjana sandstone, which resulted in the unreasonably young and unrepeatable ages of 627 ± 50 Ma and 1710 ± 110 Ma on two different aliquots. These results were attributed to incomplete Ar extraction arising from the coarse grainsize and Ar-retentive characteristics of sanidine, the major K-bearing mineral in the sample.Recently, a drilled bedrock sample from the Murray mudstone formation (termed Mojave 2) was found by the CheMin instrument to contain approximately 3.1 wt% jarosite. Jarosite is precipitated from acidic, sulfate-rich waters and is a suitable mineral for KAr dating. On a large scale, jarosite has been thought to signal the aridification of Mars and a shift towards a cold, dry environment. The small amount of jarosite in this sample prohibits generalization to a larger Martian context. However, since jarosite forms strictly through interaction with water, the K-Ar age of the jarosite in Mojave 2 puts a maximum age constraint on the last time liquid water was present at the sample site. By extension, it could also indicate the time of the very final stages of evaporation from the lake in Gale Crater.A two-step heating experiment was designed to obtain the K-Ar age of the jarosite, which accounts for about 20% of the K2O in the sample. The remainder of the K2O exists in plagioclase, an amorphous component, and possibly a small amount in K-bearing phyllosilicates

Laminated Perovskite Photovoltaics: Enabling Novel Layer Combinations and Device Architectures

High‐efficiency perovskite‐based solar cells can be fabricated via either solution‐processing or vacuum‐based thin‐film deposition. However, both approaches limit the choice of materials and the accessible device architectures, due to solvent incompatibilities or possible layer damage by vacuum techniques. To overcome these limitations, the lamination of two independently processed half‐stacks of the perovskite solar cell is presented in this work. By laminating the two half‐stacks at an elevated temperature (≈90 °C) and pressure (≈50 MPa), the polycrystalline perovskite thin‐film recrystallizes and the perovskite/charge transport layer (CTL) interface forms an intimate electrical contact. The laminated perovskite solar cells with tin oxide and nickel oxide as CTLs exhibit power conversion efficiencies of up to 14.6%. Moreover, they demonstrate long‐term and high‐temperature stability at temperatures of up to 80 °C. This freedom of design is expected to access both novel device architectures and pairs of CTLs that remain usually inaccessible

Drying Dynamics of Solution‐Processed Perovskite Thin‐Film Photovoltaics: In Situ Characterization, Modeling, and Process Control

A key challenge for the commercialization of perovskite photovoltaics is the transfer of high‐quality spin coated perovskite thin‐films toward applying industry‐scale thin‐film deposition techniques, such as slot‐die coating, spray coating, screen printing, or inkjet printing. Due to the complexity of the formation of polycrystalline perovskite thin‐films from the precursor solution, efficient strategies for process transfer require advancing the understanding of the involved dynamic processes. This work investigates the fundamental interrelation between the drying dynamics of the precursor solution thin‐film and the quality of the blade coated polycrystalline perovskite thin‐films. Precisely defined drying conditions are established using a temperature‐stabilized drying channel purged with a laminar flow of dry air. The dedicated channel is equipped with laser reflectometry at multiple probing positions, allowing for in situ monitoring of the perovskite solution thin‐film thickness during the drying process. Based on the drying dynamics as measured at varying drying parameters, namely at varying temperature and laminar air flow velocity, a quantitative model on the drying of perovskite thin‐films is derived. This model enables process transfer to industry‐scale deposition systems beyond brute force optimization. Via this approach, homogeneous and pinhole‐free blade coated perovskite thin‐films are fabricated, demonstrating high power conversion efficiencies of up to 19.5% (17.3% stabilized) in perovskite solar cells

Chemical vapor deposited polymer layer for efficient passivation of planar perovskite solar cells

Reducing non-radiative recombination losses by advanced passivation strategies is pivotal to maximize the power conversion efficiency (PCE) of perovskite solar cells (PSCs). Previously, polymers such as poly(methyl methacrylate), poly(ethylene oxide), and polystyrene were successfully applied in solution-processed passivation layers. However, controlling the thickness and homogeneity of these ultra-thin passivation layers on top of polycrystalline perovskite thin films is a major challenge. In response to this challenge, this work reports on chemical vapor deposition (CVD) polymerization of poly(p-xylylene) (PPX) layers at controlled substrate temperatures (14–16 °C) for efficient surface passivation of perovskite thin films. Prototype double-cation PSCs using a ∼1 nm PPX passivation layer exhibit an increase in open-circuit voltage (V$_{OC}$) of ∼40 mV along with an enhanced fill factor (FF) compared to a non-passivated PSC. These improvements result in a substantially enhanced PCE of 20.4% compared to 19.4% for the non-passivated PSC. Moreover, the power output measurements over 30 days under ambient atmosphere (relative humidity ∼40–50%) confirm that the passivated PSCs are more resilient towards humidity-induced degradation. Considering the urge to develop reliable, scalable and homogeneous deposition techniques for future large-area perovskite solar modules, this work establishes CVD polymerization as a novel approach for the passivation of perovskite thin films

Infrared Behavior of Three-Point Functions in Landau Gauge Yang-Mills Theory

Analytic solutions for the three-gluon and ghost-gluon vertices in Landau gauge Yang-Mills theory at low momenta are presented in terms of hypergeometric series. They do not only show the expected scaling behavior but also additional kinematic divergences when only one momentum goes to zero. These singularities, which have also been proposed previously, induce a strong dependence on the kinematics in many dressing functions. The results are generalized to two and three dimensions and a range of values for the ghost propagator's infrared exponent kappa.Comment: 21 pages, 29 figures; numerical data of the infrared dressing functions can be obtained from the authors v2: a few minor changes, corresponds to version appearing in EPJ

Curie: Constraining Solar System Bombardment Using In Situ Radiometric Dating

The Curie mission would constrain the existence of the putative cataclysm by determining the age of samples directly sourced from the impact melt sheet of a major pre-Imbrium lunar basin. The measurements would also enable further understanding of lunar evolution by characterizing new lunar lithologies far from the Apollo and Luna landing sites, including the very low-Ti basalts in Mare Crisium and potential olivine rich lithologies in the margins of both Mare Nectaris and Mars Crisium. Equipped with a mass spectrometer and a LIBS, Curie would also be well-placed to survey volatile components of the lunar regolith, including surface-bound hydrogen

On the infrared scaling solution of SU(N) Yang-Mills theories in the maximally Abelian gauge

An improved method for extracting infrared exponents from functional equations is presented. The generalizations introduced allow for an analysis of quite complicated systems such as Yang-Mills theory in the maximally Abelian gauge. Assuming the absence of cancellations in the appropriately renormalized integrals the only consistent scaling solution yields an infrared enhanced diagonal gluon propagator in support of the Abelian dominance hypothesis. This is explicitly shown for SU(2) and subsequently verified for SU(N), where additional interactions exist. We also derive the most infrared divergent scaling solution possible for vertex functions in terms of the propagators' infrared exponents. We provide general conditions for the existence of a scaling solution for a given system and comment on the cases of linear covariant gauges and ghost anti-ghost symmetric gauges.Comment: 23 pages, 10 figures; version coincides with version published in EPJ

Vacuum‐Assisted Growth of Low‐Bandgap Thin Films (FA0.8_{0.8}MA0.2_{0.2}Sn0.5_{0.5}Pb0.5_{0.5}I3_{3}) for All‐Perovskite Tandem Solar Cells

All-perovskite multijunction photovoltaics, combining a wide-bandgap (WBG) perovskite top solar cell (EG ≈1.6–1.8 eV) with a low-bandgap (LBG) perovskite bottom solar cell (EG 33%. While the research on WBG perovskite solar cells has advanced rapidly over the past decade, LBG perovskite solar cells lack PCE as well as stability. In this work, vacuum-assisted growth control (VAGC) of solution-processed LBG perovskite thin films based on mixed Sn–Pb perovskite compositions is reported. The reported perovskite thin films processed by VAGC exhibit large columnar crystals. Compared to the well-established processing of LBG perovskites via antisolvent deposition, the VAGC approach results in a significantly enhanced charge-carrier lifetime. The improved optoelectronic characteristics enable high-performance LBG perovskite solar cells (1.27 eV) with PCEs up to 18.2% as well as very efficient four-terminal all-perovskite tandem solar cells with PCEs up to 23%. Moreover, VAGC leads to promising reproducibility and potential in the fabrication of larger active-area solar cells up to 1 cm²

Nanostructured front electrodes for perovskite/c-Si tandem photovoltaics

The rise in the power conversion efficiency (PCE) of perovskite solar cells has triggered enormous interest in perovskite-based tandem photovoltaics. One key challenge is to achieve high transmission of low energy photons into the bottom cell. Here, nanostructured front electrodes for 4-terminal perovskite/crystalline-silicon (perovskite/c-Si) tandem solar cells are developed by conformal deposition of indium tin oxide (ITO) on self-assembled polystyrene nanopillars. The nanostructured ITO is optimized for reduced reflection and increased transmission with a tradeoff in increased sheet resistance. In the optimum case, the nanostructured ITO electrodes enhance the transmittance by ∼7% (relative) compared to planar references. Perovskite/c-Si tandem devices with nanostructured ITO exhibit enhanced short-circuit current density (2.9 mA/cm2 absolute) and PCE (1.7% absolute) in the bottom c-Si solar cell compared to the reference. The improved light in-coupling is more pronounced for elevated angle of incidence. Energy yield enhancement up to ∼10% (relative) is achieved for perovskite/c-Si tandem architecture with the nanostructured ITO electrodes. It is also shown that these nanostructured ITO electrodes are also compatible with various other perovskite-based tandem architectures and bear the potential to improve the PCE up to 27.0%