Nanoparticle composites as functional materials for novel devices:Chemical sensing and optoelectronic applications

Nanoparticle composites are promising regarding their applications in novel electronic devices. These materials generally comprise nanoparticles embedded in matrices that consist e.g. of short molecules or polymers. Their optical, electronic, mechanical and sorption properties are manifold, widely tunable, and depend on the particle material as well as their matrix. We demonstrate the syntheses of different tailor-made nanoparticles and their integration into prototypical devices. On the one hand, composite materials of cross-linked gold nanoparticles (GNPs) are well-known for their chemiresistive properties. Here, we show a novel sensing method, employing these materials as micro-/nanoelectromechanical (MEMS/NEMS) chemical sensors. Nanometer-thin GNP membranes are fabricated and electrostatically actuated. The resulting static deflections and resonant vibrations are strongly influenced by the adsorption of volatile organic compounds, and can hence be employed as sensing signals. In combination with their chemiresistive properties such composites can thus act as multivariate sensing platforms. On the other hand, we present semiconductor nanoparticles synthesized following highly reproducible, high-throughput, continuous-flow syntheses. Due to the quantum-size effect, they offer absorption and emission features extending over the visible (CdSe/CdS) and infrared (PbS) range. Herein, we demonstrate the integration of such particles as emitters in QLEDs and highlight their potential as absorber materials in IR photodetectors.