Light-Induced Aggregation of Gold Nanoparticles and Photoswitching of Silicon Surface Potential

Hybrid nanomaterials having tunable properties that can be reversibly conducted by external stimuli, in a particular light, are of great importance since they enable synergetic behavior between their components and enable the design of stimuli responsive smart materials and surfaces. Here we describe the formation of organic inorganic hybrid nanoparticles that photochemically aggregate and their effect on the electronic properties of a semiconducting surface, as a function of external irradiation. The inorganic component consists of 3 nm gold nanoparticles while the organic component is a covalently attached, photochromic spiropyran derivative. Aggregation/deaggregation patterns in solution were obtained and analyzed by UV vis spectroscopy and transmission electron microscopy upon photoswitching. The assembly of spiropyran-modified gold nanoparticles on an Si/SiO2 surface proved useful in phototuning the electronic properties of semiconductors measured by contact potential difference.