Tanya MS David, Wondwosson Arasho, O’Neil Smith, Kunlun Hong, Carl Bonner and Sam-Shajing Sun
Conjugated oligomers and polymers are very attractive for potential future plastic electronic and opto-electronic device applications such as plastic photo detectors and solar cells, field effect transistors, and light emitting diodes. There are many desirable properties of conjugated polymers for opto-electronic devices such as flexibility and tenability, as well as their conductive property. Understanding and optimizing charge transport between an active polymer layer and conductive substrate is critical to the optimization of opto-electronic devices. This study focused on the design, synthesis, self-assembly, and electron transfers of conjugated polymers that are covalently attached to a conductive or semi-conductive substrate. Specifically, a phosphonic acid end-functionalized polyphenylenevinylene (PPV) was developed and self-assembled onto an Indium Tin Oxide (ITO) substrate. This study demonstrated how atomic force microscopy (AFM) can be an effective characterization technique in conjunction with conventional electron transfer rate study methods, including cyclic voltammetry (CV), towards determining electron transfer rate in polymer and polymer/ conductor interface systems. This study found that the electron transfer rates of covalently attached and self-assembled films were much faster than the spin coated films. The knowledge from this study can be very useful for designing potential polymer based electronic and opto-electronic thin film devices.