In our work, we investigated a blend of low optical-gap diketopyrrolopyrrole (DPP) polymer and a fullerene derivative: PC₇₀BM for photovoltaic applications.
This blends exhibits a near-zero driving force of ~50 meV for interfacial electron transfer. Using femtosecond transient absorption (TA) and electro-absorption (EA) spectroscopy we quantify the charge transfer (CT) and recombination dynamics as well as the charge transport at early (< 1 ns) timescales.

This work was carried out in the "FemtoMat Research Group" of Prof. Natalie Banerji.

References:

• R. Shivhare, G. J. Moore, A. Hofacker, S. Hutsch, Y. Zhong, M. Hambsch, T. Erdmann, A. Kiriy, S. C. Mannsfeld, F. Ortmann, N. Banerji;
  "Short Excited-State Lifetimes Mediate Charge-Recombination Losses in Organic Solar Cell Blends with Low Charge-Transfer Driving Force"
  Advanced Materials, 2021, 34(22), 2101784/1-11; doi:10.1002/adma.202101784.