Exciton and Charge Dynamics in Polymer Solar Cells Studied by Transient Absorption Spectroscopy

Abstract

Transient absorption spectroscopy is a powerful tool for studying the photovoltaic conversion events in polymer solar cells, which occur on a wide temporal scale from ~10-15 s for exciton generation by photon absorption to ~10-5 s for charge collection to the electrode. This chapter describes first how to assign transient species such as singlet and triplet excitons, polarons, and other charge carriers by transient absorption spectroscopy. On the basis of the assignments, the exciton and charge dynamics are analyzed to discuss photophysical fundamental events related to the photovoltaic conversion such as exciton delocalization, energy transfer, triplet formation, and charge generation and recombination. Finally, the relevance to the device performance is summarized.