Photocurrent and Photovoltage Generation Dynamics at the Organic Semiconductor/Water Interface in p-Type Conjugated Polymers

Photoactive organic semiconductors are envisioned as a novel class of materials able to transduce light into stimulating signals inside biological cells or tissue. The direct interface between the semiconductor and the electrolyte gives rise to different, competing electrochemical phenomena. A detailed understanding of such chemical and photo-induced interactions is necessary to develop and optimize future devices. We addressed the problem in organic polymeric photoelectrodes by gaining insights into the energetics of the involved processes, identifying the kinetics of light stimulated charge transfer processes, and then determining the role of interfacial energy levels in the photoactivated processes. We highlight how energy diagrams enable a comprehensive understanding of the photoelectrochemical reaction pathways.