Time-Evolution of Poly(3-Hexylthiophene) as an Energy Relay Dye in Dye-Sensitized Solar Cells

Energy relay dyes (ERD) and Forster resonant energy transfer (FRET) are useful techniques for increasing absorption in dye-sensitized solar cells. We use femtosecond transient absorption spectroscopy to monitor charge generation processes in a solid-state DSC containing poly(3-hexylthiophene) (P3HT) as both the hole-transporter and the ERD with a zinc phthalocyanine dye (TT1) as the sensitizer. We observe efficient FRET occurring on picosecond time scales and subsequent hole transfer from TT1 to P3HT occurring onward from 100 ps.