Hybrid silicon-carbon nanostructures for broadband optical absorption

Abstract

Proper design of nanomaterials for broadband light absorption is a key factor for improving the conversion efficiency of solar cells. Here we present a hybrid design of silicon-carbon nanostructures with silicon clusters coated by carbon cages, i.e., Sim@C2n for potential solar cell application. The optical properties of these hybrid nanostructures were calculated based on time dependent density function theory (TDDFT). The results show that the optical spectra of Sim@C2n are very different from those of pure Sim and C2n clusters. While the absorption spectra of pure carbon cages and Sim clusters exhibit peaks in the UV region, those of the Sim@C2n nanostructures exhibit a significant red shift. Superposition of the optical spectra of various Sim@C2n nanostructures forms a broad-band absorption, which extends to the visible light and infrared regions. The broadband adsorption of the assembled Sim@C2n nanoclusters may provide a new approach for the design of high efficiency solar cell nanomaterials.