FABRICATION OF QUANTUM DOT-POLYMER COMPOSITES - SEMICONDUCTOR NANOCLUSTERS IN DUAL-FUNCTION POLYMER MATRICES WITH ELECTRON-TRANSPORTING ANDCLUSTER-PASSIVATING PROPERTIES

Hybrid inorganic-organic polymer composites have been prepared by a co nvergent approach in which nearly monodisperse CdSe or(CdSe)ZnS nanocl usters are sequestered within phosphine-containing domains in a charge -transporting matrix. The motivation for these studies is the potentia l utility of such composites as combined electron-transport and emitte r layers in light-emitting devices. Diblock copolymers with electronic ally passivating and charge-transport capabilities were prepared via r ing-opening metathesis polymerization of octylphosphine- and oxadiazol e-functionalized norbornenes. Independently prepared CdSe and ZnS-over coated CdSe nanoclusters, surface-passivated by trioctylphosphine and trioctylphosphine oxide groups, are tethered by polymer-bound phosphin e donors, resulting in immediate, sustained increases in fluorescence. Thin films of the CdSe-block copolymer composites, static-cast from d ilute solution, exhibit microphase separation, with segregation of nan oclusters within phosphine-rich microdomains. Under similar conditions , (CdSe)ZnS clusters undergo macrophase separation. Rapid-casting tech niques arrest morphological development at an earlier stage, giving sm all micelles of a few nanoclusters each in phosphine-containing domain s. Dispersion of electronically passivated nanoclusters throughout a f unctionalized polymer matrix leads to composites with a broad range of potential applications, including light-emitting devices and photovol taic cells.