Solvent Tuning of the Active Layer Morphology of Non‐Fullerene Based Organic Solar Cells

Non‐fullerene acceptor (NFA)‐based organic solar cells have made tremendous progress in recent years. For the neat NFA system PBDB‐T:ITIC, the film morphology and crystallinity are tailored by the choice of the solvent used for spin coating the active layers. Three different chlorinated solvents, ch...

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Bibliographic Details
Published in:Solar RRL 2022-06, Vol.6 (6), p.n/a
Main Authors: Grott, Sebastian, Kotobi, Amir, Reb, Lennart K., Weindl, Christian L., Guo, Renjun, Yin, Shanshan, Wienhold, Kerstin S., Chen, Wei, Ameri, Tayebeh, Schwartzkopf, Matthias, Roth, Stephan V., Müller-Buschbaum, Peter
Format: Article
Language:English
Subjects:
Active Layer
Blend films
Chlorine compounds
Crystallinity
Crystallites
Crystallization kinetics
Device performance
Film crystallinity
Film morphology
Fullerenes
Gi-SAXS
GISAXS
High power conversion
Layer morphology
morphology
Non-fullerene acceptor
non-fullerene acceptors
organic solar cells
Organic solvents
Power conversion efficiencies
solvents
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Summary:Non‐fullerene acceptor (NFA)‐based organic solar cells have made tremendous progress in recent years. For the neat NFA system PBDB‐T:ITIC, the film morphology and crystallinity are tailored by the choice of the solvent used for spin coating the active layers. Three different chlorinated solvents, chlorobenzene (CB), chloroform, and dichlorobenzene, are compared and the obtained active layer morphology is correlated with the optoelectronic properties and the device performance. The small domain sizes in the case of CB are most beneficial for the device performance, whereas the largest number or size of face‐on PBDB‐T crystallites is not causing the highest power conversion efficiencies (PCEs). In addition, when using CB, the number of edge‐on crystallites is highest and the distances between neighboring domains are small. The smoothest blend films are realized with CB, which exhibit correlated roughness with their substrates and no large aggregates have formed in these blend films. Thus, CB offers the best way to balance the aggregation and crystallization kinetics in the active layer and enables the highest PCE values. By using different solvents for spin coating, the active layers of non‐fullerene‐based organic solar cells, the film morphology, and crystallinity of donor and acceptor are tailored. Among the studied solvents, chlorobenzene offers the best way to balance the aggregation and crystallization kinetics in the active layer and thus gives the best performing solar cells.
ISSN:2367-198X
2367-198X
DOI:10.1002/solr.202101084