Control of molecular doping in conjugated polymers by thermal annealing

Abstract

Doping is one of the most fundamental building blocks for semiconductor processing, and enables adaptation to both charge concentration and electrical conductivity. Despite attempts to investigate various doping and de-doping methods for organic semiconductors over many years, their use has been limited to date. Here, we present a method to precisely control the degree of doping in dopant-implanted thiophene-based polymeric conductors. A simple post annealing at a relatively low temperature of approximately 110 °C can significantly diminish the charge carrier concentration with precision, where the controllability is evaluated comprehensively using electron spin resonance and optical absorption techniques. At higher doping regimes, a band-like charge transport with an ideal Hall effect and weak localization is confirmed.