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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 31: P3: Hybrid Photovoltaics and Preovskites

CPP 31.5: Poster

Dienstag, 17. März 2015, 14:00–16:00, Poster B

Electrical atomic force microscopy on perovskite films — •Ilka M. Hermes, Victor W. Bergmann, Simon A. Bretschneider, Frédéric Laquai, Rüdiger Berger, and Stefan A.L. Weber — Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

Organolead trihalide perovskite solar cells have reached power conversion efficiencies (PCE) of more than 20%, yet not enough is known about the physics within the perovskite layer. Unusual effects have been reported, such as strong hysteretic behavior in the photocurrent-voltage curves of the cells. It remains unclear how this effect is related to the high PCE and if mechanisms like ferroelectricity or the accumulation of trapped charges cause the hysteresis. One way to tackle these questions is to investigate the nanoscale function of perovskite films, e.g. by atomic force microscopy in working devices [1].

In this work, the electronic and electromechanical properties of perovskite films were studied on nanometer scale with electrical atomic force microscopy methods. With piezoresponse force microscopy (PFM), the local piezoelectric response was visualized, providing information on possible ferroelectric domains within the film. Conductive atomic force microscopy (CAFM) was used to measure the local photocurrent. With Kelvin probe force microscopy (KPFM) contact potential variations and light-induced potential changes could be locally resolved. These experiments help to improve the understanding of the working principles of perovskite solar cells.

[1] Bergmann, V.W. et al (2014); Nature Comm. 5, 5001