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Charge Transport in Pure and Mixed Phases in Organic Solar Cells
Author(s) -
Melianas Armantas,
Pranculis Vytenis,
Spoltore Donato,
Benduhn Johannes,
Inganäs Olle,
Gulbinas Vidmantas,
Vandewal Koen,
Kemerink Martijn
Publication year - 2017
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.201700888
Subject(s) - materials science , acceptor , organic solar cell , charge (physics) , chemical physics , buckminsterfullerene , picosecond , charge carrier , quantum tunnelling , fullerene , optoelectronics , chemistry , condensed matter physics , optics , organic chemistry , physics , polymer , laser , quantum mechanics , composite material
In organic solar cells continuous donor and acceptor networks are considered necessary for charge extraction, whereas discontinuous neat phases and molecularly mixed donor–acceptor phases are generally regarded as detrimental. However, the impact of different levels of domain continuity, purity, and donor–acceptor mixing on charge transport remains only semiquantitatively described. Here, cosublimed donor–acceptor mixtures, where the distance between the donor sites is varied in a controlled manner from homogeneously diluted donor sites to a continuous donor network are studied. Using transient measurements, spanning from sub‐picoseconds to microseconds photogenerated charge motion is measured in complete photovoltaic devices, to show that even highly diluted donor sites (5.7%–10% molar) in a buckminsterfullerene matrix enable hole transport. Hopping between isolated donor sites can occur by long‐range hole tunneling through several buckminsterfullerene molecules, over distances of up to ≈4 nm. Hence, these results question the relevance of “pristine” phases and whether a continuous interpenetrating donor–acceptor network is the ideal morphology for charge transport.