Enhanced Collective Electron Transport by CdSe Quantum Dots Confined in the Poly(4-vinylpyridine) Nanodomains of a Poly(styrene-b-4-vinylpyridine) Diblock Copolymer Thin Film

摘要

Semiconductor nanoparticle (NP) quantum dots (QDs) that have sizes close to their Bohr exciton radius (typically between 1 and 10 nm) display size-dependent band gaps and hence tunable optical properties. As a result, they exhibit a wide range of electrical and optical properties and can be used for various applications, such as light-emitting diodes, solar cells, lasers, and transistors. In these applications, composite materials consisting of nanoparticles and organic materials are often adopted. Thus, an understanding of the collective electron transport of QDs dispersed in organic materials is of both scientific and technological importance. A number of reports have described three- and two-dimensional electron transport in ordered arrays of Au NPs in SiO2 superlattices, ZnO QD assemblies, and organically capped CdSe QDs. Electron transport also has been examined in granular films of Au NPs linked by alkanethiol molecules or poly(4-vinylpyridine) and Au/spacer/CdSe QD assemblies. Orbital-selective electron transport through a single CdSe QD has been measured by scanning tunneling microscopy.