title: Correlation of annealing time with crystal structure, composition, and electronic properties of CH3NH3PbI3-xClxmixed-halide perovskite films.
abstract: Using 3D imaging with time-of-flight secondary ion mass spectrometry (ToF-SIMS) complemented by grazing-incidence X-ray diffraction (GIXRD), we spatially resolve changes in both the composition and structure of CH3NH3I3-xClxperovskite films on conducting polymer substrates at different annealing stages, in particular, before and after complete perovskite crystallization. The early stage of annealing is characterized by phase separation throughout the entire film into domains with perovskite and domains with a dominating chloride-rich phase. After sufficiently long annealing, one single perovskite phase of homogeneous composition on the (lateral) micrometer scale is observed, along with pronounced film texture. This composition evolution is accompanied by diffusion of chloride from the perovskite layer towards the conducting polymer substrate, and even accumulation there. Photoelectron spectroscopy analysis further shows that perovskite films become increasingly n-type with annealing time and upon full conversion, which correlates with the change of film composition. Our results accentuate the importance of chloride for the formation of crystalline and textured films, which are crucial for enhancing the PV performance of perovskite-based solar cells.
authors.affiliation: Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 6, 12489 Berlin, Germany.
authors.forename: Maryline
authors.initials: M
authors.lastname: Ralaiarisoa
authors.affiliation: Research Center in the Physics of Matter and Radiation (PMR), Laboratoire Interdisciplinaire de Spectroscopie Electronique (LISE), University of Namur, Rue Joseph Grafé 2, 5000 Namur, Belgium.
authors.forename: Yan
authors.initials: Y
authors.lastname: Busby
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany. nkoch@physik.hu-berlin.de.
authors.forename: Johannes
authors.initials: J
authors.lastname: Frisch
authors.affiliation: Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 6, 12489 Berlin, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Salzmann
authors.affiliation: Research Center in the Physics of Matter and Radiation (PMR), Laboratoire Interdisciplinaire de Spectroscopie Electronique (LISE), University of Namur, Rue Joseph Grafé 2, 5000 Namur, Belgium.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Pireaux
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany. nkoch@physik.hu-berlin.de.
authors.forename: Norbert
authors.initials: N
authors.lastname: Koch