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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 38: Fundamentals of Perovskite Photovoltaics V (joint session CPP/DS/HL)

CPP 38.2: Vortrag

Mittwoch, 22. März 2017, 10:45–11:00, ZEU 250

Role of Microstructure on Oxygen Induced Photodegradation of Methylammonium Lead Triiodide Perovskite Films — •Paul Fassl, Qing Sun, David Becker-Koch, Alexandra Bausch, and Yana Vaynzof — Kirchhoff-Institute for Physics / Centre for Advanced Materials, Heidelberg University, Germany.

We investigate the impact of microstructure on the degradation rate of methylammonium lead iodide (MAPbI3) perovskite films upon exposure to light and oxygen. By comparing the oxygen induced degradation of perovskite films of different microstructure fabricated either using a lead acetate trihydrate precursor or a solvent engineering technique, we demonstrate that films with larger and uniform grains as well as higher electronic quality show a significantly reduced degradation when compared to films with smaller more irregular grains. We characterize the effect of degradation on the optical, compositional and microstructural properties of the perovskite layers and demonstrate that oxygen induced degradation is initiated at the layer surface and grain boundaries. We find that under illumination, irreversible degradation can occur at oxygen levels as low as 1%, suggesting that degradation can commence already during the device fabrication stage. Finally, our work establishes that improved thin-film microstructure, with large uniform grains and low density of defects, is a prerequisite for enhanced stability necessary in order to make MAPbI3 a promising long lived and low cost alternative for future photovoltaic applications.