Rutherford Backscattering Spectroscopy of Mass Transport by Transformation of PbI2 into CH3NH3PbI3 within np-TiO2

Albert Juma, F Lang, V Somsongkul, Thomas Dittrich, M Arunchaiya

Research output: Contribution to journalArticle

Abstract

Mass transport during transformation of PbI2 infiltrated in nanoporous TiO2
into CH3NH3PbI3 has been investigated by Rutherford backscattering spectroscopy (RBS). Fast initial reaction kinetics were confirmed using optical ex-situ and in-situ measurements. Mapping with energy dispersive X-ray spectroscopy of the cross section of samples revealed a homogeneous PbI2
infiltration in nanoporous TiO2 before transformation but an accumulation of Pb and I at the surface after transformation, in accordance with a depletion of Pb and I in a near surface region. Quantitative depth profiles of Pb and I were obtained from RBS analysis. An instant degradation of CH3NH3PbI3 to PbI2
and volatiles upon ion radiation was found. The concentration profiles of
Pb could be simulated with a one dimensional diffusion model taking into account an effective diffusion coefficient of Pb in the nanocomposite (about 1.5⋅10-11 cm²/s) as well as a parameter considering frazzling at the surface due to formation of crystallites.
Original languageEnglish
Pages (from-to)52-61
JournalHybrid Materials
Volume1
Issue number1
DOIs
Publication statusPublished - 2014

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