Issue 23, 2022

Stoichiometry dependent phase evolution of co-evaporated formamidinium and cesium lead halide thin films

Abstract

Due to its scalability, thermal evaporation is an important processing route for perovskites in order to ensure the transition from research to commercialization. In this study, we focus on vacuum co-deposition of (i) FAPbI3, (ii) (Cs,FA)PbI3 and (iii) (Cs,FA)Pb(I,Br)3 at room temperature and investigate the influence of stoichiometrical variations on the development of α and δ phases. Considering the standard perovskite term APbX3, where A = FA and/or Cs and X = I and/or Br, we use EDX to determine the specific ratios of A/Pb, Cs/FA as well as X/Pb, respectively. We find, that at room temperature, the FAPbI3 δ phase is not easily suppressed. But, in both, FAPbI3 and (Cs,FA)PbI3, more AX leads to a strong increase in α phase growth while more PbI2 leads to an increase in δ phase. Incorporation of Cs slightly reduces the observed AX/PbX2 threshold, at which the δ phase is suppressed. Finally, when Br is introduced to the layer, this threshold is reduced far below 3.

Graphical abstract: Stoichiometry dependent phase evolution of co-evaporated formamidinium and cesium lead halide thin films

Supplementary files

Article information

Article type
Paper
Submitted
05 May 2022
Accepted
10 Oct 2022
First published
12 Oct 2022
This article is Open Access
Creative Commons BY license

Mater. Adv., 2022,3, 8695-8704

Stoichiometry dependent phase evolution of co-evaporated formamidinium and cesium lead halide thin films

K. L. Heinze, P. Wessel, M. Mauer, R. Scheer and P. Pistor, Mater. Adv., 2022, 3, 8695 DOI: 10.1039/D2MA00507G

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