Regensburg 2016 – scientific programme
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DS: Fachverband Dünne Schichten
DS 29: Hybrid and Perovskite Photovoltaics III
(Joint session of CPP, DS and HL, organized by DS)
DS 29.4: Talk
Wednesday, March 9, 2016, 10:15–10:30, H11
Influence of annealing time on crystal structure and composition of CH3NH3PbI3-xClx mixed halide perovskite film — •Maryline Ralaiarisoa1, Yan Busby2, Johannes Frisch1, Ingo Salzmann1, Jean-Jacques Pireaux2, and Norbert Koch1 — 1Humboldt-Universität zu Berlin, Institut für Physik, Brook-Taylor-Str. 6, 12489 Berlin, Germany — 2Research Center in the Physics of Matter and Radiation , Laboratoire Interdisciplinaire de Spectroscopie Electronique (LISE), University of Namur, 5000 Namur, Belgium
Thermal annealing is a crucial step for the formation of crystalline perovskite films from precursor solution. However, the structural evolution during perovskite film formation and particularly its composition during annealing have not been thoroughly characterized yet. Such characterization is essential to understand the mechanisms leading to the complete conversion to perovskite. Using ToF-SIMS, we monitored the changes in composition and structure of CH3NH3PbI3-x Clx perovskite films after two different annealing stages, that is, before and after complete perovskite crystallization. At the early stage of annealing, our results show phase separation throughout the entire film depth into one where perovskite was formed and another where mostly the inorganic precursor PbCl2 was detected. After sufficiently long annealing, we found a single perovskite phase of homogeneous composition on the micrometer scale. By means of UPS, we further observed that perovskite films become more n-type for longer annealing time, which correlates the morphological evolution and the surface electronic structure.