Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 2: Organic-inorganic perovskite semiconductors (with O)

HL 2.2: Vortrag

Montag, 16. März 2015, 09:45–10:00, ER 164

In situ XRD monitoring of phases formed during growth of co-evaporated perovskite thin films — •Juliane Borchert¹, Paul Pistor¹, Wolfgang Fränzel¹, René Csuk², and Roland Scheer¹ — ¹Martin-Luther-University Halle-Wittenberg, Physics Department, Halle, Germany — ²Martin-Luther-University Halle-Wittenberg, Organic Chemistry Department, Halle, Germany

Currently, information on the phases and crystal structures, which form during the growth and annealing of (CH₃NH₃)Pb(I,Cl)₃ perovskite films is scarce. To gain an insight into these, we studied thin films during their growth. Films were grown through co-evaporation of (CH₃NH₃)I and PbCl₂ or PbI₂. In situ x-ray diffraction (XRD) was utilized to study phase formation in real time. Films grown by evaporation of PbCl₂ and MAI exhibited a cubic crystal structure and two different (CH₃NH₃)Pb(I_xCl_(1−x))₃ phases could be distinguished for varying (CH₃NH₃)I to PbCl₂ flux ratios. They differed in their crystal structure observed by XRD, optical absorption properties and I/I+Cl ratio (either above 0.95 or below 0.5). For films grown with PbI₂ and MAI a tetragonal structure was observed. To monitor thermally induced changes and decomposition, we studied the films during heating. Below 200^∘C, recrystallization was observed. The chlorine free films additionally showed a transition from tetragonal to cubic structure. Above 200^∘C decomposition was observed. These results show the strong dependence of the phase formation on varying growth conditions. The formed structures can be monitored and adjusted in real time with the help of in situ XRD.