Conductive nanowires (NWs) provide several advantages as a template and electrode material for solar cells due to their favorable light scattering properties. While the majority of NW solar cell architectures studied are based on semiconductor materials, metallic NWs could provide equivalent anti-reflection properties, while acting as a low-resistance back contact for charge transport, and facilitate light scattering in thin layers of semiconductors coated on the surface. However, fabrication of single-crystalline highly anti-reflective NWs on low-cost, flexible substrates remains a challenge to drive down the cost of NW solar cells. In this study, metallic Ni_xSi NW arrays are fabricated by a simple, bottom-up, and low-cost method based on the thermal decomposition of silane on the surface of flexible Ni foil substrates without the need for lithography, etching or catalysts. The optical properties of these NW arrays demonstrate broadband suppression of reflection to levels below 1% from 350 nm to 1100 nm, which is among the highest values reported for NWs. A simple route to control the diameter and density of the NWs is introduced based on variations in a carrier gas flow rate. A high-resolution TEM, XRD and TEM-EDS study of the NWs reveals that they are single crystalline, with the phase and composition varying between Ni₂Si and NiSi. The nanowire resistivity is measured to be 10⁻⁴ Ω-cm, suggesting their use as an efficient back electrode material for nanostructured solar cells with favorable light scattering properties.

This paper reports both experimental and theoretical results of the role of surface modification on the oxygen reduction reaction in low-temperature solid oxide fuel cells (LT-SOFC). Epitaxial ultrathin films of yttria-doped ceria (YDC) cathode interlayers (<10–130 nm) are grown by pulsed laser deposition (PLD) on single-crystalline YSZ(100). Fuel cell current–voltage measurements and electrochemical impedance spectroscopy are performed in the temperature range of 350 °C ≈ 450 °C. Quantum mechanical simulations of oxygen incorporation energetics support the experimental results and indicate a low activation energy of only 0.07 eV for YDC, while the incorporation reaction on YSZ is activated by a significantly higher energy barrier of 0.38 eV. Due to enhanced oxygen incorporation at the modified Pt/YDC interface, the cathodic interface resistance is reduced by two-fold, while fuel cell performance shows more than a two-fold enhancement with the addition of an ultrathin YDC interlayer at the cathode side of an SOFC element. The results of this study open up opportunities for improving cell performance, particularly of LT-SOFCs by adopting surface modification of YSZ surface with catalytically superior, ultrathin cathodic interlayers.