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Requirements for Making Thick Junctions of Organic Solar Cells based on Nonfullerene Acceptors
Author(s) -
Nyman Mathias,
Sandberg Oskar J.,
Li Wei,
Zeiske Stefan,
Kerremans Robin,
Meredith Paul,
Armin Ardalan
Publication year - 2021
Publication title -
solar rrl
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.544
H-Index - 37
ISSN - 2367-198X
DOI - 10.1002/solr.202100018
Subject(s) - organic solar cell , active layer , acceptor , electron mobility , doping , indole test , energy conversion efficiency , materials science , homo/lumo , polymer solar cell , electron acceptor , charge carrier , photovoltaic system , chemistry , optoelectronics , photochemistry , nanotechnology , stereochemistry , layer (electronics) , organic chemistry , physics , polymer , molecule , electrical engineering , thin film transistor , condensed matter physics , engineering
Organic bulk‐heterojunction solar cells based on the newly developed nonfullerene electron acceptors have the potential for very low‐cost energy production. However, to enable large‐scale production with common printing techniques, the active layer thicknesses need to be increased by up to an order of magnitude, which is currently not possible without significant loss in performance. Herein, the requirements for making nonfullerene acceptor (NFA)‐based solar cells with thick active layers and high efficiencies are clarified. The charge carrier mobility, unintentional doping concentrations, and bimolecular recombination prefactor in the model high‐efficiency system PM6 (Poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl‐3‐fluoro)thiophen‐2‐yl)‐benzo[1,2‐ b :4,5‐ b ′]dithiophene))‐ alt ‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐ c :4′,5′‐ c ′]dithiophene‐4,8‐dione)]):Y6 (2,2′‐((2 Z ,2′ Z )‐((12,13‐bis(2‐ethylhexyl)‐3,9‐diundecyl‐12,13‐dihydro‐[1,2,5]thiadiazolo[3,4‐ e ]thieno[2″,3″:4′,5′]thieno[2′,3′:4,5]pyrrolo[3,2‐ g ]thieno[2′,3′:4,5]thieno[3,2‐ b ]indole‐2,10‐diyl)bis(methanylylidene))bis(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1 H ‐indene‐2,1‐diylidene))dimalononitrile) are determined. The results are implemented in a combined electro‐optical device model, which is used to determine the effect of varying these parameters on the efficiency. The results show that a mobility imbalance and doping can lead to improved performance at large thicknesses, partially contradicting previous studies performed on fullerene‐based systems. The findings highlight the importance of determining electron and hole mobilities selectively, as well as characterizing recombination and doping concentrations.