Recently there has been significant interest in utilizing functional organic semiconductor materials for electronic and opto-electronic devices such as Light-emitting diodes, thin film field effect transistors, solar cells, displays, and chemical and biosensors. However, better materials and further understanding of their electronic properties are critical for devices based on these materials. In this work, we use various scanning probe techniques, spectroscopy, and device fabrication to study the molecular interactions and charge transport properties in conjugated polyelectrolytes. Using chemical synthesis approach, we are able to tune the molecular packing and interactions in these materials, which in turn, influence their optical and charge transport properties and device performance.