Gold-activated persulfate p-doping of organic semiconductors

Chemical doping is crucial for fine-tuning the electronic properties of organic semiconductors (OSCs) and enhancing device performance across various technologies. While several methods for controlled dopant distribution have been explored, achieving lateral doping gradients via simple solution processing remains challenging. Here we present a gold-activated persulfate doping strategy in which persulfate is catalytically activated at gold surfaces to generate SO₄^•- radicals that locally oxidize (p-dope) the OSCs. This reaction creates a lateral doping gradient extending outwards from the gold interface, as verified by spectroscopic and electrical characterization. The approach is broadly applicable to OSCs spanning a 1.5-eV ionization potential range and yields conductivities >1,900 S cm^-1. To demonstrate the impact of this method, we applied gold-activated persulfate doping to modulate contact regions in solution-processed organic field-effect transistors, achieving reduced contact resistance and improved charge-carrier mobility. This simple, scalable approach enables the formation of lateral doping gradients from solution and offers new opportunities for interfacial tuning in organic electronics.