Berlin 2012 – scientific programme

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DS: Fachverband Dünne Schichten

DS 1: Layer properties: electrical, optical, and mechanical properties

DS 1.7: Talk

Monday, March 26, 2012, 11:00–11:15, H 0111

Role of surfactants and defect generation in CdSe quantum dot layers for separation of photo-generated charge carriers — •Elisabeth Zillner, Steffen Fengler, and Thomas Dittrich — Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin

Thin layers of CdSe quantum dots (QDs) were prepared by dip coating of ITO substrates in QD suspension. Surface modification of QDs was done by surfactant exchange in suspensions and layers. Interparticle distances between QDs in layers were monitored by transmission electron microscopy. Absorption and photoluminescence spectra showed an increase in defect states by proceeding surfactant exchange. The charge separation in the CdSe QD layers was strongly influenced by the surface modification. Both spectral and time dependent SPV showed a high dependency on surfactant exchange. Results are discussed on basis of asymmetric trapping at defect states within the first monolayer of QDs at the interface during initial charge separation.