Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: Nanoparticles II

CPP 9.4: Vortrag

Montag, 23. März 2009, 14:45–15:00, ZEU 114

Study of electronic couplings between molecular and core states of 3-ethenylthiophene terminated Si quantum dots — •Vincent Groenewegen, Volker Kuntermann, Carla Cimpean, Anja Sommer, and Carola Kryschi — Dept. Chemistry and Pharmacy, Physical Chemistry I and ICMM, FAU, Egerlandstr. 3, 91058 Erlangen

One of the central challenges in fabrication of silicon quantum dots (Si qdots) tailored for nano-optolelectronics is to functionalize their surfaces with electronically efficiently coupled molecules which mediate photogenerated carrier injection into the bulk and allow to optically control charge separation as well as luminescence properties of the bulk. We have developed a wet-chemistry procedure that allows to produce Si qdots with adjustable sizes and surface properties. Here we present a fs spectroscopy and a time-dependent density function theoretical (TDDFT) study of Si qdots with sizes around 2 nm which are terminated with 3-ethenylthiophene. The photoluminescence spectra as well as the TDDFT computations unambiguously show quasi-resonant electronic interactions between the excited states of covalently bound 3-ethenylthiophene and conduction band states of the Si core. These results were confirmed by ultrafast rise dynamics of absorption transitions of conduction band electrons which were monitored with the fs transient absorption spectroscopy technique