Ultrafast Photoinduced Electron Transfer in a π-Conjugated Oligomer/Porphyrin Complex

Shawkat Mohammede Aly, Subhadip Goswami, Qana Alsulami, Kirk S. Schanze, Omar F. Mohammed

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Controlling charge transfer (CT), charge separation (CS), and charge recombination (CR) at the donor-acceptor interface is extremely important to optimize the conversion efficiency in solar cell devices. In general, ultrafast CT and slow CR are desirable for optimal device performance. In this Letter, the ultrafast excited-state CT between platinum oligomer (DPP-Pt(acac)) as a new electron donor and porphyrin as an electron acceptor is monitored for the first time using femtosecond (fs) transient absorption (TA) spectroscopy with broad-band capability and 120 fs temporal resolution. Turning the CT on/off has been shown to be possible either by switching from an organometallic oligomer to a metal-free oligomer or by controlling the charge density on the nitrogen atom of the porphyrin meso unit. Our time-resolved data show that the CT and CS between DPP-Pt(acac) and cationic porphyrin are ultrafast (approximately 1.5 ps), and the CR is slow (ns time scale), as inferred from the formation and the decay of the cationic and anionic species. We also found that the metallic center in the DPP-Pt(acac) oligomer and the positive charge on the porphyrin are the keys to switching on/off the ultrafast CT process.
Original languageEnglish (US)
Pages (from-to)3386-3390
Number of pages5
JournalThe Journal of Physical Chemistry Letters
Volume5
Issue number19
DOIs
StatePublished - Sep 18 2014

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