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Unifying Charge Generation, Recombination, and Extraction in Low‐Offset Non‐Fullerene Acceptor Organic Solar Cells
Author(s) -
Karki Akchheta,
Vollbrecht Joachim,
Gillett Alexander J.,
Selter Philipp,
Lee Jaewon,
Peng Zhengxing,
Schopp Nora,
Dixon Alana L.,
Schrock Max,
Nádaždy Vojtech,
Schauer Franz,
Ade Harald,
Chmelka Bradley F.,
Bazan Guillermo C.,
Friend Richard H.,
Nguyen ThucQuyen
Publication year - 2020
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.202001203
Subject(s) - materials science , organic solar cell , fullerene , acceptor , chemical physics , polymer solar cell , polymer , nanotechnology , energy conversion efficiency , optoelectronics , chemistry , organic chemistry , physics , composite material , condensed matter physics
Even though significant breakthroughs with over 18% power conversion efficiencies (PCEs) in polymer:non‐fullerene acceptor (NFA) bulk heterojunction organic solar cells (OSCs) have been achieved, not many studies have focused on acquiring a comprehensive understanding of the underlying mechanisms governing these systems. This is because it can be challenging to delineate device photophysics in polymer:NFA blends comprehensively, and even more complicated to trace the origins of the differences in device photophysics to the subtle differences in energetics and morphology. Here, a systematic study of a series of polymer:NFA blends is conducted to unify and correlate the cumulative effects of i) voltage losses, ii) charge generation efficiencies, iii) non‐geminate recombination and extraction dynamics, and iv) nuanced morphological differences with device performances. Most importantly, a deconvolution of the major loss processes in polymer:NFA blends and their connections to the complex BHJ morphology and energetics are established. An extension to advanced morphological techniques, such as solid‐state NMR (for atomic level insights on the local ordering and donor:acceptor ππ interactions) and resonant soft X‐ray scattering (for donor and acceptor interfacial area and domain spacings), provide detailed insights on how efficient charge generation, transport, and extraction processes can outweigh increased voltage losses to yield high PCEs.