Doping of the Semiconducting Polymer, Poly (3-hexylthiophene) (P3HT), in Organic Photoelectrochemical Cells

We demonstrate the dependence of photoelectrochemical properties of the organic semiconductor film poly(3-hexylthiophene) (P3HT) on the dopant species. We use cyclic voltammetry to characterize electrochemical doping/undoping behavior and show that the reversibility of doping/undoping depends on the incorporated anions. Irreversible doping is achieved with the incorporation of hydrophilic or bulky anions such as bromide or tetraphenylborate. The irreversible doping on the P3HT film leads to an increase in photocurrent with a high photo-to-dark current ratio. This study highlights that interaction between dopant and organic semiconductor is a significant parameter for the design of stable organic photoelectrochemical and other optoelectronic cells.