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Abstract: We have studied the charge transport physics of high-quality conducting coordination nanosheets films based on the benchmark material copper benzenehexathiol (CuBHT) by measuring multiple thermoelectric and magnetotransport coefficients on the same film. The films exhibit a metallic temperature dependence of the conductivity over a wide temperature range, but below 15 kelvin charge transport becomes dominated by weak localization and electron-electron interactions. Temperature-dependent Hall, Seebeck, and Nernst measurements consistently indicate the existence of ambipolar transport characteristics in CuBHT. A two-band analysis has been used to extract transport parameters for electron and hole carriers as a function of temperature. The results show that contributions from electron and hole conduction in CuBHT are of comparable magnitude, revealing the complexity of charge transport and allowing one to identify strategies for enhancing the thermoelectric transport coefficients of such conducting coordination nanosheets.

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Abstract: Water-insoluble organic material extracted from atmospheric aerosol samples collected in urban (Royal Holloway, University of London, UK) and remote (Halley Research Station, Antarctica) locations were shown to form stable thin surfactant films at an air–water interface. These organic films reacted quickly with gas-phase OH radicals and may impact planetary albedo. The X-ray reflectivity measurements additionally indicate that the film may be consistent with having a structure with increased electron density of film molecules towards the water, suggesting amphiphilic behaviour. Assuming the material extracted from atmospheric aerosol produces thin films on aqueous particles and cloud droplets, modelling the oxidation kinetics with a kinetic model of aerosol surface and bulk chemistry (KM-SUB) suggests half-lives of minutes to an hour and values of ksurf of and  cm2 s−1 for urban and remote aerosol film extracts, respectively. The superfluous half-lives calculated at typical OH atmospheric ambient mixing ratios are smaller than the typical residence time of atmospheric aerosols; thus, oxidation of organic material should be considered in atmospheric modelling. Thin organic films at the air–water interface of atmospheric aerosol or cloud droplets may alter the light-scattering properties of the aerosol. X-ray reflectivity measurements of atmospheric aerosol film material at the air–water interface resulted in calculated film thickness values to be either ∼10 or ∼17 Å for remote or urban aerosol extracts, respectively, and oxidation did not remove the films completely. One-dimensional radiative transfer modelling suggests the oxidation of thin organic films on atmospheric particles by OH radicals may reduce the planetary albedo by a small, but potentially significant, amount.

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Abstract: Halide perovskite solar cells are approaching commercialization, with solution processing emerging as a key method for large-scale production. This study introduces a significant advancement: using non-toxic solvents like water and alcohol in perovskite precursor inks facilitated by the protic ionic liquid methylammonium propionate (MAP). MAP effectively dissolves perovskite precursors such as lead acetate and methylammonium iodide, enabling the first stable water-based perovskite precursor ink suitable for one-step slot-die coating. This new ink formulation contrasts with conventional dimethylformamide (DMF) and dimethylsulfoxide (DMSO)-based inks, as evidenced by in-situ grazing incidence wide-angle X-ray scattering (GIWAXS), which revealed an intermediate-free liquid-to-solid transition. In-situ mass spectrometry also showed that organic molecules evaporate during annealing, resulting in a crystalline perovskite phase. Optimization of the solvent mixture to H2O/IPA/MAP enabled successful slot-die coating, yielding perovskite solar cells with an efficiency of up to 10%. This eco-friendly ink reduces toxicity and environmental impact compared to DMF-based inks, offering a longer shelf life and the possibility of using the ink in ambient conditions. This pioneering work represents the first report of a water-based green ink formulation for one-step thin film coating at room-temperature conditions by slot-die coating, highlighting its potential for sustainable commercial applications.

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Abstract: The efficiency of organic solar cells has raised drastically in the past years. However, there is an undeniable lack of hole transport layers that can provide high carrier selectivity, low defect density, and high processing robustness, simultaneously. In this work, this issue is addressed by studying defect generation and surface passivation of nickel oxide (NiOx). It is revealed that the generation of high oxidation state species on NiOx surface lowers contact resistance but hinders charge extraction when employed as transport layer in organic solar cells. By using them as coordination centers, a straightforward surface modification strategy is implemented using (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) that enhances charge extraction and increases the solar cell efficiency from 11.46% to 17.12%. Additionally, the robustness of this modification across different deposition methods of the carbazole molecule is demonstrated. Finally, by fine-tuning the Fermi level using various carbazole-based molecules, and in particular with ((4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (4PADCB), a power conversion efficiency of 17.29% is achieved, with an outstanding combination of a VOC of 0.888 V and a fill factor of 80%.

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Abstract: Grazing-incidence small-angle x-ray scattering (GISAXS) and thermal desorption spectroscopy (TDS) were used to study the thermal evolution of helium (He) bubbles in tungsten (W). W samples were exposed to a low ion energy (∼20 eV, sheath accelerated) He plasma at two sample temperatures: 573 K (low-temperature) and 1050 K (high-temperature). They were then annealed to temperatures of 773 K, 873 K and 998 K. GISAXS analysis showed an increase in the median bubble radius of the high-temperature samples from 6.42 Å to 12.87 Å as a result of annealing to 998 K. No changes in the bubble radii distributions were observed for the low-temperature samples and the median radius remained at ∼4 Å even after annealing. TDS showed that the desorption behaviour of He in W has a dependence on the sample temperature during plasma irradiation. The higher-temperature sample experienced a maximum desorption rate that is an order of magnitude larger than the low-temperature sample. The desorption profile of the high-temperature sample spanned a wider temperature range, 500 K - 1500 K, than the low-temperature sample, 500 K - 750 K. The formation and thermal evolution of He bubbles in W have a clear dependence on sample temperature during plasma exposure. The differences in annealing behaviour observed in this work agrees with prior in-situ TEM annealing experiments and helps explain macroscopic plasma-material interaction effects such as recrystallisation suppression.