Chemical Functionalization of Silicon Nanowires by an Electroactive Group: A Direct Spectroscopic Characterization of the Hybrid Nanomaterial

We report on the optical and electrochemical characterization of hybrid nanowires prepared by chemical functionalization of silicon nanowires (SiNWs) with triphenylamine (TPA) derivatives. The SiNWs synthesized by vapor-liquid-solid (VLS) process were modified directly on their growth Substrate and then break away by ultrasonication and were analyzed directly in Solution by UV-vis and fluorescence spectroscopies. These two techniques allowed a direct analysis of molecules grafted on the SiNWs whereas indirect methods are commonly used for this purpose. Coupled with X-ray photoelectron spectroscopy analysis, we demonstrate the effective anchoring of the molecules to the inorganic semiconductor and we suggest the formation of a cation radical TPA(+center dot), which is attributed to an electronic transfer from the TPA to the silicon nanowire.