Linker-Induced Anomalous Emission of Organic-Molecule Conjugated Metal-Oxide Nanoparticles
Abbreviated Journal Title
photoluminescence; semiconductor nanostructures; organic-molecule; conjugated nanoparticles; linker molecules; TITANIUM-DIOXIDE; SOLAR-CELLS; FOLIC-ACID; SURFACE; TIO2(110); DENSITY; PHOTOCATALYSIS; ADSORPTION; EXCHANGE; BEHAVIOR; Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience &; Nanotechnology; Materials Science, Multidisciplinary
Semiconductor nanoparticles conjugated with organic and dye-molecules to yield high efficiency visible photoluminescence (PL) hold great potential for many future technological applications. We show that folic acid (FA)-conjugated to nanosize TiO2 and CeO2 particles demonstrates a dramatic increase of photoemission intensity at wavelengths between 500 and 700 nm when derivatized using aminopropyl trimethoxysilane (APTMS) as spacer-linker molecules between the metal oxide and FA. Using density-functional theory (DFT) and time-dependent DFT calculations we demonstrate that the strong increase of the PL can be explained by electronic transitions between the titania surface oxygen vacancy (OV) states and the low-energy excited states of the FA/APTMS molecule anchored onto the surface oxygen bridge sites in close proximity to the OVs. We suggest this scenario to be a universal feature for a wide class of metal oxide nanoparticles, induding nanoceria, possessing a similar band gap (similar to 3 eV) and with a large surface-vacancy-related density of electronic states. We demonstrate that the molecule-nanoparticle linker can play a crucial role in tuning the electronic and optical properties of nanosystems by bringing optically active parts of the molecule and of the surface close to each other.
"Linker-Induced Anomalous Emission of Organic-Molecule Conjugated Metal-Oxide Nanoparticles" (2012). Faculty Bibliography 2010s. 3405.