This project aims at a detailed understanding of the optical and electrochemical interactions within a new organic-inorganic semiconductor hybrid nanostructure, namely PbS quantum dots and selected zinc- or cobalt-porphyrins. The porphyrins are chosen such that they contain one or four functional groups to bind to the surface of PbS QDs and replace the native ligand sphere. This way, coupled organic-inorganic nanostructures are obtained which bear the potential of significant carrier delocalization between the particle core and the ligand shell depending on the alignment of relevant energy levels between the two moieties. Such coupled nanostructures circumvent the current charge transport dilemma of solution-processed QDs by providing a channel for carrier transport through molecular orbitals of the MP.32 MPs are ideal in this context as many of them are naturally occurring, relatively inexpensive, and easy to functionalize with a large choice of substituents or different metal centers which holds for a great physicochemical variety.
As a first step towards implanting QD-MP hybrids for optoelectronic applications, in this project, we use spectroelectrochemistry and electrochemically-gated transistors to gain insights into the changes in electronic structure upon binding between the QD and MP. By comparing the optical and electrochemical data of the hybrids with the data acquired on the pure components, we seek to develop a physicochemical description of the electronic interaction between the two constituents that helps understanding carrier delocalization, and facilitates the identification of suitable candidates for future implantation into optoelectronic devices.
April 2016 - March 2016
Sabine Ludwigs (University of Stuttgart)