Cs x FA1- xPb(I1- yBr y)3 Perovskite Compositions: The Appearance of Wrinkled Morphology and its Impact on Solar Cell Performance

Research output: Contribution to journalArticle


We report on the formation of wrinkle-patterned surface morphologies in cesium formamidinium-based CsxFA1-xPb(I1-yBry)3 perovskite compositions with x = 0-0.3 and y = 0-0.3 under various spin-coating conditions. By varying the Cs and Br contents, the perovskite precursor solution concentration and the spin-coating procedure, the occurrence and characteristics of the wrinkle-shaped morphology can be tailored systematically. Cs0.17FA0.83Pb(I0.83Br0.17)3 perovskite layers were analyzed regarding their surface roughness, microscopic structure, local and overall composition, and optoelectronic properties. Application of these films in p-i-n perovskite solar cells (PSCs) with indium-doped tin oxide/NiOx/perovskite/C60/bathocuproine/Cu architecture resulted in up to 15.3 and 17.0% power conversion efficiency for the flat and wrinkled morphology, respectively. Interestingly, we find slightly red-shifted photoluminescence (PL) peaks for wrinkled areas and we are able to directly correlate surface topography with PL peak mapping. This is attributed to differences in the local grain size, whereas there is no indication for compositional demixing in the films. We show that the perovskite composition, crystallization kinetics, and layer thickness strongly influence the formation of wrinkles which is proposed to be related to the release of compressive strain during perovskite crystallization. Our work helps us to better understand film formation and to further improve the efficiency of PSCs with widely used mixed-perovskite compositions.


  • Steffen Braunger
  • Laura E. Mundt
  • Christian M. Wolff
  • Mathias Mews
  • Carolin Rehermann
  • Marko Jošt
  • Alvaro Tejada
  • David Eisenhauer
  • Christiane Becker
  • Jorge Andres Guerra
  • Eva Unger
  • Lars Korte
  • Dieter Neher
  • Martin C. Schubert
  • Bernd Rech
  • Steve Albrecht
External organisations
  • Helmholtz Association of German Research Centers
  • Fraunhofer Institute for Solar Energy Systems
  • University of Potsdam
  • Pontifical Catholic University of Peru
Original languageEnglish
Pages (from-to)17123-17135
Number of pages13
JournalJournal of Physical Chemistry C
Issue number30
Publication statusPublished - 2018 Aug 2
Publication categoryResearch
Externally publishedYes