Time-resolved Raman spectroscopy of polaron formation in a polymer photocatalyst

Piercy, Verity L and Saeed, Khezar H and Prentice, Andrew W and Neri, Gaia and Li, Chao and Gardner, Adrian M and Bai, Yang and Sprick, Reiner Sebastian and Sazanovich, Igor V and Cooper, Andrew I and Rosseinsky, Matthew J and Zwijnenburg, Martijn A and Cowan, Alexander J (2021) Time-resolved Raman spectroscopy of polaron formation in a polymer photocatalyst. Journal of Physical Chemistry Letters, 12 (44). pp. 10899-10905. ISSN 1948-7185 (https://doi.org/10.1021/acs.jpclett.1c03073)

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Abstract

Polymer photocatalysts are a synthetically diverse class of materials that can be used for the production of solar fuels such as H2, but the underlying mechanisms by which they operate are poorly understood. Time-resolved vibrational spectroscopy provides a powerful structure-specific probe of photogenerated species. Here we report the use of time-resolved resonance Raman (TR3) spectroscopy to study the formation of polaron pairs and electron polarons in one of the most active linear polymer photocatalysts for H2 production, poly(dibenzo[b,d]thiophene sulfone), P10. We identify that polaron-pair formation prior to thermalization of the initially generated excited states is an important pathway for the generation of long-lived photoelectrons.