Electronic and optical properties of strained noble metals: Implications for applications based on LSPR

The localized surface plasmon resonance (LSPR) of noble metal nanoparticles provides a means to significantly enhance light-matter interaction. Thus, it is recently introduced into photovoltaics and photocatalysis for enhancing the transformation of solar light, where the efficiency of intra- and inter-band electron transitions fundamentally affects the overall performance of the systems. Considering the commonness and tunability of strain in nanoparticles, in this work we examine its potential effects on the intra- and inter-band electron transitions and related plasmonic properties of noble metals by the first-principles calculations and Drude theory. It is meaningful to find that strain can significantly modulate the electronic structures of noble metals that are closely related to the sp intra- and d-sp inter-band electron transitions. As a consequence, compressive strain notably increases the intra- band, but decrease the inter-band electron transition probabilities in the visible and near-infrared spectral range. Moreover, it significantly increases the near-field enhancement and light absorption efficiency for the LSPR in the visible and near-infrared range. Whereas the effect of tensile strain is exactly opposite. These results are very useful as guides in optimizing the nanostructure design for higher solar energy conversion efficiency and optoelectronic devices based on the LSPR of noble metals.