Abstract
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 language | English |
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Article number | 183502 |
Journal | Applied Physics Letters |
Volume | 111 |
DOIs | |
Publication status | Published - 13 Oct 2017 |
Externally published | Yes |
MoE publication type | A1 Journal article-refereed |