The impact of driving force on electron transfer rates in photovoltaic donor-acceptor blends.

Ward, Alexander J; Ruseckas, Arvydas; Kareem, Mohanad Mousa; Ebenhoch, Bernd; Serrano, Luis A; Al-Eid, Manal; Fitzpatrick, Brian; Rotello, Vincent M et al. · Adv Mater · 2015

basic_science · Level V

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Abstract

The effect of acceptor energy level on electron transfer rate in blends of the polymer solar-cell material poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) is studied using time-resolved fluorescence. Fast electron transfer in less than 2 ps is observed for a driving force between 0.2 and 0.6 eV and the electron transfer is slower outside this range. This dependence is described by Marcus theory with a reorganization energy of ≈0.4 eV.