Local disorder at the phase transition interrupts ambipolar charge carrier transport in large crystal methylammonium lead iodide thin films

Alexander Biewald, Nadja Giesbrecht, Thomas Bein, Pablo Docampo, Achim Hartschuh, Richard Ciesielski

Research output: Contribution to journalArticleResearchpeer-review


The low-temperature transition from a tetragonal to an orthorhombic crystal phase in methylammonium lead iodide (MAPI) is accompanied by drastic changes in the charge carrier mobility around a critical temperature of approximately 164 K. This transition is studied here using photoluminescence (PL) microscopy on large crystal MAPI thin films, which is extremely sensitive to modifications of the charge carrier dynamics and can resolve physical properties on a single-grain level. The key observation is that ambipolar charge carrier diffusion suddenly stops when the temperature falls below the phase transition temperature. From coexisting PL bands and their spatial distribution, it is concluded that the temperature range from just below the phase transition until about 150 K is determined by a mixed phase where small orthorhombic and tetragonal domains coexist. This results in local disorder, which hinders ambipolar charge carrier diffusion.

Original languageEnglish
Pages (from-to)20757-20764
Number of pages8
JournalJournal of Physical Chemistry C
Issue number38
Publication statusPublished - 25 Aug 2020
Externally publishedYes

Cite this