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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 105: Focus: In-situ probes toward better understanding of hybrid halide perovskites (PhD symposium) II (joint session CPP/AKjDPG)
CPP 105.4: Vortrag
Freitag, 20. März 2020, 10:30–10:45, ZEU 222
Growth of Methylammonium and Formamidinium Lead Halides by Co-Evaporation Analyzed with in situ X-ray Diffraction — •Karl Heinze, Thomas Burwig, Roland Scheer, and Paul Pistor — Martin-Luther-Universität Halle-Wittenberg, Halle an der Saale, Germany
Crystalline lead halide perovskite (e.g. Methyl Ammonium (MA) PbI3), thin-film solar cells reach efficiencies far over 20%. These films are commonly prepared by solvent-based methods such as spin-coating, with limited scalability. An industrially attractive technique for the deposition of thin films is co-evaporation. Using a vacuum chamber with a built-in in-situ X-ray diffraction system, we are able to investigate the influence of varying processing conditions during the co-evaporation of MA lead halides (MAPbX3, with X=I,Br,Cl) and formamidinium lead halides (FAPbX3) on the film formation process and can cross-relate our findings to opto-electronic properties and solar cell performance. More specifically, we analyze the effect of different precursors flux rate ratios and substrate temperatures on the crystal growth and compare sequential to simultaneous co-evaporation. We find a strong impact of the processing temperature on crystal size and morphology and determine suitable process windows for optimal absorber compositions with small amounts of PbI2 secondary phases. We note that processing conditions have also a strong impact on the crystal orientation of the films. This is especially pronounced for FAPbBr3, where we were able to grow films with nearly complete orientation in either (100) or (111) direction.