Micro-spectroscopy of Buried Short-Range Surface Plasmon Polaritons Supported by Thin Polycrystalline Gold Films

The dispersive properties of short-range surface plasmon polaritons are investigated at the buried interfaces in vacuum/Au/fused silica and vacuum/Au/SiO2/Si multilayer systems for different gold film thicknesses of up to 50 nm using two-photon photoemission electron microscopy. The experimental data agrees excellently with results of transfer matrix method simulations, emphasizing the sensitivity of the plasmonic wave vector to the thickness of the gold film and an ultrathin native substrate oxide layer. The results furthermore illustrate the exceptional qualification of low-energy electron photoemission techniques in studying electronic excitations at buried interfaces

Detection and characterization of attenuated multimode waveguiding in SiO2 slabs using photoemission electron microscopy

Multimode waveguiding in the visible and near-ultraviolet spectral regime is observed and characterized in thermally grown SiO 2 layers on silicon using photoemission electron microscopy (PEEM). Comparison with finite-element-method simulations allows identifying order and character of the attenuated modes. Real-time investigations on mode propagation support these findings and give additional evidence for the existence of radiative modes. Finally, the presented experimental results illustrate how a defined deposition of gold nanoparticles can substantially enhance the sensitivity of the PEEM technique to electromagnetic field modes supported by thin dielectric and insulating layers

Reconsidering figures of merit for performance and stability of perovskite photovoltaics

The development of hybrid organic-inorganic halide perovskite solar cells (PSCs) that combine high performance and operational stability is vital for implementing this technology. Recently, reversible improvement and degradation of PSC efficiency have been reported under illumination-darkness cycling. Quantifying the performance and stability of cells exhibiting significant diurnal performance variations is challenging. We report the outdoor stability measurements of two types of devices showing either reversible photo-degradation or reversible efficiency improvement under sunlight. Instead of the initial (or stabilized) efficiency and T as the figures of merit for the performance and stability of such devices, we propose using the value of the energy output generated during the first day of exposure and the time needed to reach its 20% drop, respectively. The latter accounts for both the long-term irreversible degradation and the reversible diurnal efficiency variation and does not depend on the type of process prevailing in a given perovskite cell

In situ–Directed Growth of Organic Nanofibers and Nanoflakes: Electrical and Morphological Properties

Organic nanostructures made from organic molecules such as para-hexaphenylene (p-6P) could form nanoscale components in future electronic and optoelectronic devices. However, the integration of such fragile nanostructures with the necessary interface circuitry such as metal electrodes for electrical connection continues to be a significant hindrance toward their large-scale implementation. Here, we demonstrate in situ–directed growth of such organic nanostructures between pre-fabricated contacts, which are source–drain gold electrodes on a transistor platform (bottom-gate) on silicon dioxide patterned by a combination of optical lithography and electron beam lithography. The dimensions of the gold electrodes strongly influence the morphology of the resulting structures leading to notably different electrical properties. The ability to control such nanofiber or nanoflake growth opens the possibility for large-scale optoelectronic device fabrication