Enhanced Lifetime of Excitons in Nonepitaxial Au/CdS Core/Shell

摘要: The ability of metal nanoparticles to capture light throughplasmonexcitationsoffersanopportunityforenhancingthe optical absorption plasmon-coupled semiconductor materials via energy transfer. This process, however, requires that the semicon- ductor component is electrically insulated prevent a "backward" charge flow into and interfacial states, which causes premature dissociation excitons. Here we demonstrate such an exchange can be achieved on nanoscale by using nonepitaxial Au/CdS core/shell nanocomposites. These are fabricated multistep cation reaction, decouples phases leading fewer defects. Ultrafast transient measurementsconfirmthatthelifetimeofexcitonsintheCdSshell(τ ≈300ps)ismuchlongerthanlifetimesofexcitonsinconventional,reduction-grown heteronanostructures. As result, efficiently utilized without undergoingsignificantnonradiativeenergylosses,animportantpropertyforcatalyticorphotovoltaicapplications.Thereducedrateofexcitondissociation intheCdSdomainof Au/CdSnanocompositeswasattributed tothe nonepitaxialnatureof Au/CdSinterfaces associatedwith lowdefect densityand ahigh potential barrier interstitial phase.