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

Zhong, Yufei; Causa', Martina; Moore, Gareth John; Krauspe, Philipp; Xiao, Bo; Günther, Florian; Kublitski, Jonas; Shivhare, Rishi; Benduhn, Johannes; BarOr, Eyal; Mukherjee, Subhrangsu; Yallum, Kaila M.; Réhault, Julien; Mannsfeld, Stefan C. B.; Neher, Dieter; Richter, Lee J.; DeLongchamp, Dean M.; Ortmann, Frank; Vandewal, Koen; Zhou, Erjun; ... (2020). Sub-picosecond charge-transfer at near-zero driving force in polymer:non-fullerene acceptor blends and bilayers. Nature Communications, 11(1) Springer Nature 10.1038/s41467-020-14549-w

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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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Zhong, Yufei; Causa', Martina; Moore, Gareth John; Krauspe, Philipp Jonathan; Yallum, Kaila Morgan; Réhault, Julien Emile and Banerji, Natalie

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

2041-1723

Publisher:

Springer Nature

Funders:

[4] Swiss National Science Foundation

Language:

English

Submitter:

Olivier Nicolas Ludovic Bardagot

Date Deposited:

02 Mar 2020 16:14

Last Modified:

08 Mar 2020 02:50

Publisher DOI:

10.1038/s41467-020-14549-w

Related URLs:

Additional Information:

Funding sources: - SNSF: Type: Förderungsprofessur, Grant number: PP00P2_150536 - University of Bern

BORIS DOI:

10.7892/boris.140597

URI:

https://boris.unibe.ch/id/eprint/140597

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