Polymer memristors with light weight and mechanical flexibility are preeminent candidates for low-power edge computing paradigms. However, the structural inhomogeneity of most polymers usually leads to random resistive switching characteristics, which lowers the production yield and reliability of nanoscale devices. In this contribution, we report that by adopting the two-dimensional conjugation strategy, a record high 90% production yield of polymer memristors has been achieved with miniaturization and low power potentials. By constructing coplanar macromolecules with 2D conjugated thiophene derivatives to enhance the π–π stacking and crystallinity of the thin film, homogeneous switching takes place across the entire polymer layer, with fast responses in 32 ns, D2D variation down to 3.16% ~ 8.29%, production yield approaching 90%, and scalability into 100 nm scale with tiny power consumption of ~ 10−15 J/bit. The polymer memristor array is capable of acting as both the arithmetic-logic element and multiply-accumulate accelerator for neuromorphic computing tasks.
We proposed a method to enhance the characteristics of undoped ZnO films by H2 post-treatment using photochemical vapor deposition. The resistivity of a H2-treated film decreased from 1×10−2 to 2×10−3 Ω cm, the haze ratio increased from 37% to 48%, and no degradation of total transmittance was observed. There are two possible explanations for these phenomena. First, hydrogen atoms assist the desorption of oxygen atoms from the film, resulting in decreased resistivity. Second, hydrogen atoms etch small grains growing among large ones on the surface of the film, resulting in a rough surface.
Electrical conductivity in quantum dot solids is crucial for application in devices. In addition to the well-known ligand exchange strategies for enhanced conductivity, the current study examined the optical, structural, and electrical properties of ethanedithiol-treated layer-by-layer (LbL) assembled quantum dot solid (QDS) films following low-temperature annealing (room temperature to 170 °C). As the annealing temperature increased, it was induced that the average separation between nanocrystal quantum dots is decreased, and accordingly, the overall conductivity of the QDS increased exponentially. From a simplified percolation model, the activation energy of temperature-dependent quantum dot attachment was estimated to be around 0.26−0.27 eV both for PbS and PbSe quantum dot solids. Furthermore, the results of this study indicated that device applications requiring higher conductivity, attainable through high-temperature annealing, may also require repassivation after annealing.
A new generation of the "flexure-based microgap rheometer" (the N-FMR) has been developed which is also capable of measuring, in addition to the shear stress, the first normal stress difference of micrometer thin fluid films. This microgap rheometer with a translation system based on compound spring flexures measures the rheological properties of microliter samples of complex fluids confined in a plane couette configuration with gap distances of h = 1-400 μm up to shear rates of γ = 3000 s(-1). Feed back loop controlled precise positioning of the shearing surfaces with response times <1 ms enables to control the parallelism within 1.5 μrad and to maintain the gap distance within 20 nm. This precise gap control minimizes squeeze flow effects and allows therefore to measure the first normal stress difference N(1) of the thin film down to a micrometer gap distance, with a lower limit of N(1)/γ = 9.375×10(-11) η/h(2) that depends on the shear viscosity η and the squared inverse gap. Structural development of complex fluids in the confinement can be visualized by using a beam splitter on the shearing surface and a long working distance microscope. In summary, this new instrument allows to investigate the confinement dependent rheological and morphological evolution of micrometer thin films.
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