Berlin 2018 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 23: Organic Photovoltaics I
CPP 23.8: Talk
Tuesday, March 13, 2018, 11:45–12:00, C 243
Charge Carrier Recombination Dynamics in Squaraine-Based Bulk-Heterojunction Solar Cells — •Dorothea Scheunemann1, Oliver Kolloge1, Sebastian Wilken1, Majvor Mack1, Jürgen Parisi1, Matthias Schulz2, Arne Lützen2, and Manuela Schiek1 — 1University of Oldenburg, Institute of Physics, Energy and Semiconductor Research Laboratory, 26111 Oldenburg — 2University of Bonn, Kekulé Institute of Organic Chemistry and Biochemistry, 53121 Bonn
Squaraine (SQ) dyes receive increasing attention as donor materials in organic photovoltaics since they combine high absorption in the deep-red with a general environmental stability and non-toxicity. Together with common fullerene acceptors, SQ-based bulk-heterojunction devices have been demonstrated to deliver a high open-circuit voltage, but suffer from a comparatively low fill factor [1]. However, little effort has been made to develop a better understanding of the underlying loss mechanisms. In this work, we focus on transient optoelectronic characterization methods to study the loss mechanisms in photovoltaic devices of a benchmark squaraine (SQIB) blended with a fullerene (PC60BM). These devices show a gradual decrease of the fill factor when increasing the active layer thickness and incident light intensity. We show that the low fill factor is a consequence of slow charge carrier collection competing with bimolecular recombination.
[1] Scheunemann et al., Appl. Phys. Lett. 111 (2017) 183502.