Requirements for Making Thick Junctions of Organic Solar Cells based on Nonfullerene Acceptors

Mathias Nyman*, Oskar J. Sandberg*, Wei Li, Stefan Zeiske, Robin Kerremans, Paul Meredith, Ardalan Armin*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)

Abstract

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′-((2Z,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-1H-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.

Original languageEnglish
Article number2100018
JournalSolar Rrl
Volume5
Issue number5
DOIs
Publication statusPublished - Mar 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • charge carrier mobilities
  • doping
  • nonfullerene acceptors
  • organic photovoltaics
  • recombination

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