Issue 1, 2017

Correlation of annealing time with crystal structure, composition, and electronic properties of CH3NH3PbI3−xClx mixed-halide perovskite films

Abstract

Using 3D imaging with time-of-flight secondary ion mass spectrometry (ToF-SIMS) complemented by grazing-incidence X-ray diffraction (GIXRD), we spatially resolve changes in both the composition and structure of CH3NH3I3−xClx perovskite films on conducting polymer substrates at different annealing stages, in particular, before and after complete perovskite crystallization. The early stage of annealing is characterized by phase separation throughout the entire film into domains with perovskite and domains with a dominating chloride-rich phase. After sufficiently long annealing, one single perovskite phase of homogeneous composition on the (lateral) micrometer scale is observed, along with pronounced film texture. This composition evolution is accompanied by diffusion of chloride from the perovskite layer towards the conducting polymer substrate, and even accumulation there. Photoelectron spectroscopy analysis further shows that perovskite films become increasingly n-type with annealing time and upon full conversion, which correlates with the change of film composition. Our results accentuate the importance of chloride for the formation of crystalline and textured films, which are crucial for enhancing the PV performance of perovskite-based solar cells.

Graphical abstract: Correlation of annealing time with crystal structure, composition, and electronic properties of CH3NH3PbI3−xClx mixed-halide perovskite films

Supplementary files

Article information

Article type
Paper
Submitted
14 Sep 2016
Accepted
30 Nov 2016
First published
30 Nov 2016
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2017,19, 828-836

Correlation of annealing time with crystal structure, composition, and electronic properties of CH3NH3PbI3−xClx mixed-halide perovskite films

M. Ralaiarisoa, Y. Busby, J. Frisch, I. Salzmann, J. Pireaux and N. Koch, Phys. Chem. Chem. Phys., 2017, 19, 828 DOI: 10.1039/C6CP06347K

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