Application of two-dimensional (2D) organic–inorganic hybrid halide perovskites in optoelectronic devices requires a detailed understanding of the local structural features including the Pb–I bonding in the 2D layers and the organic–inorganic interaction between the organic spacer molecules and the perovskite layer. In this study, we show that ¹H and ²⁰⁷Pb solid-state nuclear magnetic resonance (NMR) spectroscopy can serve as a noninvasive and complementary technique to probe the local structural features of the 2D Ruddlesden–Popper phase BA₂MA_n–1Pb_nI_3n+1 (n = 1–4) with butylammonium (BA) spacers. ²⁰⁷Pb echo and ²⁰⁷Pb → ¹H heteronuclear correlation experiments enable layer-by-layer structural detection of 2D halide perovskites. We show that the observed correlation between ²⁰⁷Pb NMR shifts and mean Pb–I bond lengths around each Pb site allows us to probe the local bonding environment of Pb. We envisage that this technique will be vital for a better understanding of the properties of materials as determined by the local atomistic environments in multidimensional halide perovskites.

Authors : Jeongjae Lee, Woocheol Lee, Keehoon Kang*, Takhee Lee*, and Sung Keun Lee*

Chem. Mater. 33, 370-377 (2021)

Link: https://doi.org/10.1021/acs.chemmater.0c04078