Sub-picosecond charge-transfer at near-zero driving force in polymer:non-fullerene acceptor blends and bilayers

Published

February 11, 2020

Author(s)

Yufei Zhong, Martina Causa, Gareth J. Moore, Philipp Krauspe, Bo Xiao, Jonas Kublitski, Rishi Shivhare, Johannes Benduhn, Eyal BarOr, Subhrangsu Mukherjee, Kaila Yallum, Julien R?hault, Stefan C. Mannsfeld, Dieter Neher, Lee J. Richter, Dean DeLongchamp, Frank Ortmann, Koen Vandewal, Erjun Zhou, Banerji Natalie, Florian Gunther

Abstract

Organic photovoltaics based on non-fullerene acceptors (NFAs) show record efficiency of 16 to 17% and increased photovoltage owing to the low driving force for interfacial charge-transfer. However, the low driving force potentially slows down charge generation, leading to a tradeoff between voltage and current. Here, we disentangle the intrinsic charge-transfer rates from morphology-dependent exciton diffusion for a series of polymer:NFA systems. Moreover, we establish the influence of the interfacial energetics on the electron and hole transfer rates separately. We demonstrate that charge-transfer timescales remain at a few hundred femtoseconds even at near-zero driving force, which is consistent with the rates predicted by Marcus theory in the normal region, at moderate electronic coupling and at low re-organization energy. Thus, in the design of highly efficient devices, the energy offset at the donor:acceptor interface can be minimized without jeopardizing the charge-transfer rate and without concerns about a current-voltage tradeoff.

Citation

Nature Communications

Pub Type

Journals

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https://doi.org/10.1038/s41467-020-14549-w

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Citation

Zhong, Y. , Causa, M. , Moore, G. , Krauspe, P. , Xiao, B. , Kublitski, J. , Shivhare, R. , Benduhn, J. , BarOr, E. , Mukherjee, S. , Yallum, K. , R?hault, J. , Mannsfeld, S. , Neher, D. , Richter, L. , DeLongchamp, D. , Ortmann, F. , Vandewal, K. , Zhou, E. , Natalie, B. and Gunther, F. (2020), Sub-picosecond charge-transfer at near-zero driving force in polymer:non-fullerene acceptor blends and bilayers, Nature Communications, [online], https://doi.org/10.1038/s41467-020-14549-w, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928665 (Accessed October 1, 2025)