Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 19: Hybrid and Perovskite Photovoltaics I (Joint session of CPP, DS and HL, organized by CPP)
HL 19.7: Vortrag
Montag, 7. März 2016, 16:45–17:00, H38
Iodine Migration and its Effect on Hysteresis in Perovskite Solar Cells — Cheng Li1, Steffen Tscheuscher2, Fabian Paulus3, Paul Hopkinson3, Johannes Kiessling1, Anna Köhler2, Yana Vaynzof3, and •Sven Hüttner1 — 1Organic and Hybrid Electronics, Makromol. Chemie I, Universität Bayreuth — 2Experimentalphysik II, Universität Bayreuth — 3Centre for Advanced Materials, Universität Heidelberg
Solution-processed organic-inorganic hybrid perovskite solar cells (e.g. CH3NH3PbI3−xClx) currently exhibit promising performances. However, the origin of the observed hysteresis in the current-voltage (J-V) curves, i.e. the sweeping-history-dependent electrical current, is still not sufficiently understood. To investigate its origin we employ electroabsorption (EA) spectroscopy to explore the built-in potential in working photovoltaic devices. Furthermore, we study the temperature dependent dynamic processes in perovskite solar cells by characterizing their current-voltage behavior at different temperatures. The electrical current relaxation process during temperature dependent J-V measurements provides the evidence of the migration of ions. In order to investigate the nature of these ions, we further present X-ray photoemission spectroscopy (XPS) experiments which shows the elemental redistribution after applying an electrical bias. The results give a concise picture that mainly iodide ions can be driven by an external electrical field and then accumulate at the respective perovskite/electrode interfaces. The migration and accumulation of iodide ions create a modulation of the respective interfacial barriers which is the origin of the hysteresis.