Ultrafast photoinduced electron transfer in a pi-conjugated oligomer/porphyrin complex

Ultrafast photoinduced electron transfer in a pi-conjugated oligomer/porphyrin complex

Ultrafast photoinduced electron transfer in a pi-conjugated oligomer/porphyrin complex
Shawkat M. Aly, Subhadip Goswami, Qana A. Alsulami, Kirk S. Schanze, and Omar F. Mohammed
J. Phys. Chem. Lett. 5(19), pp 3386-3390, (2014)
Shawkat M. Aly, Subhadip Goswami, Qana A. Alsulami, Kirk S. Schanze, and Omar F. Mohammed
Platinum-oligomer, Ultrafast charge transfer, Cationic porphyrin, Femtosecond transient absorption spectroscopy
2014

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 communication, 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 broadband capability and 120 fs temporal resolution. Turning the CT on/off has been shown to be possible either by switching from organometallic oligomer to 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 very 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 charge transfer process.



DOI: 10.1021/jz5018174