Surface Polarization Drives Photoinduced Charge Separation at the P3HT/Water Interface

Edoardo Mosconi, Paolo Salvatori, Maria Ilenia Saba, Alessandro Matton, Sebastiano Bellani, Francesco Bruni, Beatriz Santiago Gonzalez, Maria Rosa Antognazza, Sergio Brovelli, Guglielrno Lanzani, Hong Li, Jean-Luc Bredas, Filippo De Angelie

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

Hybrid devices employing organic semiconductors interfaced with an aqueous solution represent a new frontier in bioelectronics and energy applications. Understanding of the energetics and photoinduced processes occurring at the organic/water interface is fundamental for further progress. Here, we investigate the interfacial electronic structure of poly-3-hexylthiophene (P3HT) sandwiched between an indium tin oxide (ITO) electrode and a liquid water electrolyte. The aqueous solution is found to polarize the polymer outermost layers, which together with the polymer p-(photo) doping by dissolved oxygen localizes photogenerated electrons at the P3HT/water interface, while holes can be transferred to the ITO electrode. Under illumination, the polymer/water interface is negatively charged, attracting positive ions from the electrolyte solution and perturbing the ion distribution in the aqueous solution. The observed mechanism is of general character and could underlie the behavior of a variety of devices characterized by an organic/water interface, such as prosthetic devices for artificial vision and organic-based systems for photoelectrochemical applications.
Original languageEnglish (US)
Pages (from-to)454-463
Number of pages10
JournalACS Energy Letters
Volume1
Issue number2
DOIs
StatePublished - Jul 27 2016

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