Counteranion Effects on the Incorporation of Photosystem I with Poly(3,4-ethylenedioxythiophene) (PEDOT)

Conductive polymers provide an effective interface for proteins, particularly in photovoltaic applications. The synthetic toolbox affords a variety of options in which to fine-tune protein-polymer properties toward better engineered materials. While prior work has shown compatibility between Poly(3,4-ethylenedioxythiophene) (PEDOT) and Photosystem I, a detailed study of counteranion effects with interfacing Photosystem I has yet to be performed. This study, which fills a significant gap in the field, involves the synthesis of PEDOT films with a variety of different potassium-based salts. Morphology, capacitance, and impedances all varied across the films when deposited in the presence of the different anions. These properties were evaluated independently before interfacing PSI. After incorporating PSI within these films through entrapment and deposition approaches, the counteranion dependent properties were explored further through the photoactivity of these composite films. Results showed that films produced with the bromide anion provided the highest photocurrent output due to the porous leaf-like structure of the conducting polymer matrix.