Revealing the recombination dynamics in squaraine-based bulk heterojunction solar cells

Dorothea Scheunemann*, Oliver Kolloge, Sebastian Wilken, Majvor Mack, Jürgen Parisi, Matthias Schulz, Arne Lützen, Manuela Schiek

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

12 Citations (Scopus)


We combine steady-state with transient optoelectronic characterization methods to understand the operation of photovoltaic devices based on a benchmark model squaraine blended with a fullerene acceptor. These devices suffer from a gradual decrease in the fill factor when increasing the active layer thickness and incident light intensity. Using transient photocurrent, transient photovoltage, and bias-assisted charge extraction measurements, we show that the fill factor deteriorates due to slow charge carrier collection competing with bimolecular recombination. Under normal operating conditions, we find a bimolecular recombination rate constant of ∼10–17 m3 s−1, which corresponds to a reduction of one to two orders of magnitude compared to the Langevin model.
Original languageEnglish
Article number183502
JournalApplied Physics Letters
Publication statusPublished - 13 Oct 2017
Externally publishedYes
MoE publication typeA1 Journal article-refereed


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