Shedding Light on the Moisture Stability of 3D/2D Hybrid Perovskite Heterojunction Thin Films

Schlipf, Johannes; Hu, Yinghong; Pratap, Shambhavi; Biessmann, Lorenz; Hohn, Nuri; Porcar, Lionel; Bein, Thomas; Docampo, Pablo and Müller-Buschbaum, Peter (2019): Shedding Light on the Moisture Stability of 3D/2D Hybrid Perovskite Heterojunction Thin Films. In: ACS Applied Energy Materials, Vol. 2, No. 2: pp. 1011-1018

Abstract

To increase the moisture stability of hybrid perovskite photovoltaics, a combination of three-dimensional (3D) and a thin layer of two-dimensional (2D) perovskite incorporating long-chained organic cations is often employed as photoabsorber. However, the detailed interaction between water and 3D/2D perovskite heterojunctions has not been elucidated yet. Using in situ neutron and X-ray scattering techniques, we reveal surprisingly strong water uptake into 3D/2D perovskite films despite the presence of hydrophobic bulky cations. Our results show rapid disproportionation of the initial 2D phase (number of layers, m = 5) in methylammonium lead iodide (MAPI)/2D films into lower m phases under humidity. Nevertheless, the 2D perovskite inhibits the irreversible PbI2 formation, which suggests that the suppression of land MA(+) ion migration and consequently of MAI escape is related to the improved moisture stability of MAPI/2D perovskite films. In comparison, quadruple-cation perovskites including Rb+ exhibit poor stability toward phase segregation upon exposure to moisture regardless of the 2D perovskite layer.

• Item Type: Journal article
• Faculties: Chemistry and Pharmacy > Department of Chemistry
• Research Centers: Center for NanoScience (CENS)
• Subjects: 500 Science > 540 Chemistry; 500 Science > 500 Science
• ISSN: 2574-0962
• Language: English