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

Author(s):Show less -

Zhong, Yufei ^[1] ; Causa', Martina ^[1] ; Moore, Gareth John ^[1] ; Krauspe, Philipp ^[1] ; Xiao, Bo ^[2] ; Guenther, Florian ^[3] ; Kublitski, Jonas ^{[4, 5]} ; Shivhare, Rishi ^{[4, 5]} ; Benduhn, Johannes ^{[4, 5]} ; BarOr, Eyal ^[6] ; Mukherjee, Subhrangsu ^[7] ; Yallum, Kaila M. ^[1] ; Rehault, Julien ^[1] ; Mannsfeld, Stefan C. B. ^{[4, 5]} ; Neher, Dieter ^[6] ; Richter, Lee J. ^[7] ; DeLongchamp, Dean M. ^[7] ; Ortmann, Frank ^[8] ; Vandewal, Koen ^[9] ; Zhou, Erjun ^[2] ; Banerji, Natalie ^[1]

Affiliation

^[1] Univ Bern, Dept Chem & Biochem, Freiestr 3, CH-3012 Bern - Switzerland

^[2] Natl Ctr Nanosci & Technol, CAS Ctr Excellence Nanosci, Chinese Acad Sci CAS Key Lab Nanosyst & Hierarch, Beijing 100190 - Peoples R China

^[3] Univ Sao Paulo, IFSC, Av Trabalhador Saocarlense 400, BR-13560970 Sao Carlos - Brazil

^[4] Tech Univ Dresden, Dresden Integrated Ctr Appl Phys & Photon Mat IAP, Nothnitzer Str 61, D-01187 Dresden - Germany

^[5] Tech Univ Dresden, Inst Appl Phys, Nothnitzer Str 61, D-01187 Dresden - Germany

^[6] Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam Golm - Germany

^[7] NIST, Mat Measurement Lab, Gaithersburg, MD 20899 - USA

^[8] Tech Univ Dresden, Ctr Adv Elect Dresden, Helmholtzstr 18, D-01062 Dresden - Germany

^[9] Hasselt Univ, Inst Mat Res IMO IMOMEC, Wetenschapspk 1, B-3590 Diepenbeek - Belgium

• Document type: Journal article
• Source: NATURE COMMUNICATIONS; v. 11, n. 1 FEB 11 2020.
• Web of Science Citations: 40

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. (AU)

• FAPESP's process: 18/15670-5 - Novel Semiconducting Materials based on PDMS and DPP for Flexible and Stretchable Electronics: Fabrication, Analysis and Applications in Organic Devices
• Grantee: Florian Steffen Günther
• Support Opportunities: Scholarships in Brazil - Post-Doctoral