Interaction of oxygen with halide perovskites. Issue 23 (29th May 2018)

• Record Type: Journal Article
• Authors: Senocrate, Alessandro; Acartürk, Tolga; Kim, Gee Yeong; Merkle, Rotraut; Starke, Ulrich; Grätzel, Michael; Maier, Joachim
• Is Part Of: Journal of materials chemistry. Volume 6:Issue 23(2018)
• Page Start: 10847
• Page End: 10855
• Publication Date: 2018-05-29
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c8ta04537b
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Thermodynamics shows halide perovskites to be highly unstable against oxygen. Light accelerates O2 interaction kinetics. The materials stays metastable in the dark. Abstract : We systematically investigate the consequences of exposing halide perovskites to an oxygen-containing atmosphere, in particular methylammonium lead iodide, the archetypal compound used as photo-absorber in perovskite solar cells. For this purpose, we study oxygen solubility and global reaction with oxygen both in the dark and under light, and we refer to the kinetics in terms of surface reaction and bulk diffusion. As thermodynamics reveals, the material is unstable against oxygen, primarily because of the large driving force of water formation. While under light the material quickly degrades, in the dark the surface reaction kinetics – not the bulk transport – is very sluggish and keeps it metastable. For the same reason, oxygen incorporation into the lattice is negligible in the dark. On illumination, an accelerated oxygen in-diffusion occurs (as shown by 18 O incorporation experiments) that severely modifies the electronic and ionic conductivities in the way that is expected for an acceptor dopant. Lastly, we investigate the impact of cation as well as anion mixing on the degradation and stress the necessity of using encapsulation during solar cell operation.