Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 8: Organic-Inorganic Perovskite Semiconductors (HL with CPP)
O 8.2: Talk
Monday, March 16, 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(IxCl(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.