A method for laying out arrays of components in programmable 2D arrangements with nanometer-scale precision is needed for the manufacture of high density nanoelectronic circuitry. We report programmed self-assembly of gold prototype nanoelectronic components into closely packed rows with precisely defined inter-row spacings by in situ hybridization of DNA-functionalized components to a preassembled 2D DNA scaffolding on a surface. This approach is broadly applicable to the manufacture of nanoscale integrated circuits for logic, memory, sensing, and other applications.

The applications of organotin halide perovskites are limited because of their chemical instability under ambient conditions. Upon air exposure, Sn2+ can be rapidly oxidized to Sn4+, causing a large variation in the electronic properties. Here, the role of organic cations in degradation is investigated by comparing methylammonium tin iodide (MASnI3) and formamidinium tin iodide (FASnI3). Through chemical analyses and theoretical calculations, it is found that the organic cation strongly influences the oxidation of Sn2+ and the binding of H2O molecules to the perovskite lattice. On the one hand, Sn2+ can be easily oxidized to Sn4+ in MASnI3, and replacing MA with FA reduces the extent of Sn oxidation; on the other hand, FA forms a stronger hydrogen bond with H2O than does MA, leading to partial expansion of the perovskite network. The two processes compete in determining the material's conductivity. It is noted that the oxidation is a difficult process to prevent, while the water effect can be largely suppressed by reducing the moisture level. As a result, FASnI3‐based conductors and photovoltaic cells exhibit much better reproducibility as compared to MASnI3‐based devices. This study sheds light on the development of stable Pb‐free perovskite optoelectronic devices through new material design.

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This work investigates the macroscopic thermomechanical behavior of lunar boulders by modeling their response to diurnal thermal forcing. Our results reveal a bimodal, spatiotemporally-complex stress response. During sunrise, stresses occur in the boulders' interiors that are associated with large-scale temperature gradients developed due to overnight cooling. During sunset, stresses occur at the boulders' exteriors due to the cooling and contraction of the surface. Both kinds of stresses are on the order of 10 MPa in 1 m boulders and decrease for smaller diameters, suggesting that larger boulders break down more quickly. Boulders ≤30 cm exhibit a weak response to thermal forcing, suggesting a threshold below which crack propagation may not occur. Boulders of any size buried by regolith are shielded from thermal breakdown. As boulders increase in size (>1 m), stresses increase to several 10s of MPa as the behavior of their surfaces approaches that of an infinite halfspace. As the thermal wave loses contact with the boulder interior, stresses become limited to the near-surface. This suggests that the survival time of a boulder is not only controlled by the amplitude of induced stress, but also by its diameter as compared to the diurnal skin depth. While stresses on the order of 10 MPa are enough to drive crack propagation in terrestrial environments, crack propagation rates in vacuum are not well constrained. We explore the relationship between boulder size, stress, and the direction of crack propagation, and discuss the implications for the relative breakdown rates and estimated lifetimes of boulders on airless body surfaces.