Conversion of light into direct current is important for applications ranging from energy conversion to photodetection, yet often challenging over broad photon frequencies. Here we show a new architecture based on surface plasmon excitation within a metal-insulator-metal device that produces power based on spatial confinement of electron excitation through plasmon absorption. Plasmons excited in the upper metal are absorbed, creating a high concentration of hot electrons which can inject above or tunnel through the thin insulating barrier, producing current. The theoretical power conversion efficiency enhancement achieved can be almost 40 times larger than that of direct illumination while utilizing a broad spectrum of IR to visible wavelengths. Here we present both theoretical estimates of the power conversion efficiency and experimental device measurements, which show clear rectification and power conversion behavior.

Previous work has indicated that an important component for the initiation of autoimmune insulin-dependent diabetes mellitus (IDDM) in the NOD mouse model entails MHC class I-restricted CD8 T cell responses against pancreatic β cell Ags. However, unless previously activated in vitro, such CD8 T cells have previously been thought to require helper functions provided by MHC class II-restricted CD4 T cells to exert their full diabetogenic effects. In this study, we show that IDDM development is greatly accelerated in a stock of NOD mice expressing TCR transgenes derived from a MHC class I-restricted CD8 T cell clone (designated AI4) previously found to contribute to the earliest preclinical stages of pancreatic β cell destruction. Importantly, these TCR transgenic NOD mice (designated NOD.AI4αβ Tg) continued to develop IDDM at a greatly accelerated rate when residual CD4 helper T cells were eliminated by introduction of the scid mutation or a functionally inactivated CD4 allele. In a previously described stock of NOD mice expressing TCR transgenes derived from another MHC class I-restricted β cell autoreactive T cell clone, IDDM development was retarded by elimination of residual CD4 T cells. Hence, there is variability in the helper dependence of CD8 T cells contributing to the development of autoimmune IDDM. The AI4 clonotype represents the first CD8 T cell with a demonstrated ability to progress from a naive to functionally activated state and rapidly mediate autoimmune IDDM development in the complete absence of CD4 T cell helper functions.

This study reports the preparation of Al2O3 and TiO2 coatings on the as-prepared LiCoO2 electrodes using atomic layer deposition (ALD). A thin Al2O3 ALD coating was shown to eliminate capacity fading effectively during repeated charging and discharging, whereas a TiO2 coating led to significant improvement only at high cycle numbers. An analysis of the differential capacity versus potential curves suggests that this poorer cycling performance could be related to the participation of the TiO2 thin film in the redox reaction. Graphical representation of the energy levels of the various ALD coatings on LiCoO2 during charging and discharging indicated that the redox current is impeded at the Al2O3–LiCoO2 junction, whereas electrons and holes were energetic enough to flow into the TiO2 because of the smaller band gap energy. The barrier between the valence band maxima of TiO2 and LiCoO2 expands as the charge–discharge cycle number increases, eventually making TiO2 redox-inactive. These conclusions are supported by both XPS spectra and the cycle performance in the established literature references. Our results suggest that large band gap materials should be considered to be potentially useful ALD coatings on cathode materials.

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Wavelength separation and detection is generally performed by spatial dispersal of incident light onto separate detectors, or by appropriate wavelength-selective filters. Here we demonstrate direct wavelength determination of monochromatic light in a power-independent fashion with a single metal-insulator-metal device. This simple platform allows facile fabrication and scaling, and may be useful for on-chip optical communications. Although a single wavelength is power-independent, with two or more concurrent input signals, the output obeys a simple current sum rule, allowing the output to be tuned by choosing the input wavelengths and power. Finally, we demonstrate real-time deconvolution of three different wavelength asynchronous signals.

In situ diffuse reflectance infrared Fourier‐transformed spectroscopy (DRIFTS) investigations have been made to examine solid‐electrolyte interphase (SEI) formation on lithium‐rich Li1.2Ni0.2Mn0.6O2 (LLNMO) and LiCoO2 cathodes during first‐ and second‐cycle charging and discharging. This DRIFTS technique allows us to clarify SEI formation with different charging voltages. Both cathodes revealed the formation of the same surface species during first‐cycle charging, initially including ethylene carbonate (EC) adsorption, and SEI species, for example, ROCOF, RCOOR, Li2CO3, ROCO2Li, and PFx, are formed above the onset potential, namely 4.0 and 4.5 V for LiCoO2 and LLNMO, respectively. The onset potentials correspond to the upper limit of the reversible redox potential range for transition‐metal couples (e.g. Co3+/Co4+ in LiCoO2 and Ni2+/Ni4+ in LLNMO), which account for the intrinsic instability of these cathode materials. Such results suggest the participation of intermediate reactive oxygen species in SEI formation. SEI species continue to form during the discharge process when the potential is scanned cathodically below 3.6 and 4.0 V for LiCoO2 and LLNMO, respectively. Similar SEI species are also observed during the second cycle charge–discharge over LLNMO, where additional oxidized species such as carboxylate (−COO−) and CO2 are also found during charging. With the exception of PFx, all of the observed SEI species can be attributed to the oxidative decomposition of the organic solvent, EC. Finally, possible reaction mechanisms related to the oxidative decomposition of EC are discussed.

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