Electrochemical and optical properties of layer-by-layer self assembled cadmium selenide nanocomposites for devices.

摘要

CdSe nanoparticles (NPs) have attracted great interest in opto-electronic applications due to their unique size-dependent electro-optical properties and n-type semiconducting behavior. On the other hand, organic semiconductors (OSCs) such as conjugated polymers, oligomers, and precursor polymers have been extensively studied and applied technologically due to their p-type semiconductor-like optical and electronic properties. Thus, the integration of CdSe NPs with organic semiconductors in photovoltaic cells (PVs) and light emitting diodes (LEDs) has stimulated wide interest in recent years. However, the device processability needs to be improved in order to compete with commercially available alternative devices. Therefore, the investigation of organic semiconductors and the proper assembly of layered nanocomposites with CdSe NPs that maintains a bi-continuous inorganic phase, nanomorphology, and percolation paths for charge transport is of great importance. Understanding the electrochemical and optical properties of such nanocomposites plays a crucial role in designing well-defined donor-acceptor interfaces for photoinduced exciton dissociation and charge transport in PVs and energy transfer and charge transport in LEDs. This dissertation details (i) the synthesis and characterization of water soluble CdSe NPs, conjugated polymers, oligomers and precursor polymers, (ii) the characterization of the electrostatic layer-by-layer self-assembled nanometer scale layered thin films, (iii) the interpretation of the energy level diagram at the donor-acceptor interface using electro-optical data, and (iv) the correlation of the charge transfer/energy transfer and thermodynamic cascade of charges for donor-acceptor interfaces. The findings should eventually be useful towards developing optimal layered device fabrication control for both PV and LED applications.