Regarding the role of aggregation and structural order on the mechanism of molecular doping of semiconducting polymers : from solutions to films Polymeric semiconductors are strong contenders for replacing traditional inorganic semiconductors in electronic applications requiring low power low cost and flexibility such as biosensors flexible solar cells and electronic displays. Molecular doping has the potential to enable this revolution by improving the conductivity and charge transport properties of this class of materials. Despite decades of research in this field gaps in our understanding of the nature of dopant–polymer interactions has resulted in limited commercialization of this technology. This work aims at providing a deeper insight into the underlying mechanisms of molecular p doping of semiconducting polymers in the solution and solid state and thereby bring the scientific community closer to realizing the dream of making organic semiconductors commonplace in the electronics industry. The role of 1) dopant size shape 2) polymer chain aggregation and 3) charge delocalization on the doping mechanism and efficiency is addressed using optical (UV Vis NIR) and ...