Direct investigation of the reorientational dynamics of A-site cations in 2D organic-inorganic hybrid perovskite by solid-state NMR
Cheng‐Chieh Lin, Shing‐Jong Huang, Pei‐Hao Wu, Tzu-Pei Chen, Chih-Ying Huang, Ying‐Chiao Wang, Po‐Tuan Chen, Denitsa Radeva, Ognyan Petrov, Vladimir Gelev, Raman Sankar, Chia‐Chun Chen, Chun‐Wei Chen, Tsyr‐Yan Yu
Abstract
Abstract Limited methods are available for investigating the reorientational dynamics of A-site cations in two-dimensional organic–inorganic hybrid perovskites (2D OIHPs), which play a pivotal role in determining their physical properties. Here, we describe an approach to study the dynamics of A-site cations using solid-state NMR and stable isotope labelling. 2 H NMR of 2D OIHPs incorporating methyl-d 3 -ammonium cations (d 3 -MA) reveals the existence of multiple modes of reorientational motions of MA. Rotational-echo double resonance (REDOR) NMR of 2D OIHPs incorporating 15 N- and ¹³C-labeled methylammonium cations ( 13 C, 15 N-MA) reflects the averaged dipolar coupling between the C and N nuclei undergoing different modes of motions. Our study reveals the interplay between the A-site cation dynamics and the structural rigidity of the organic spacers, so providing a molecular-level insight into the design of 2D OIHPs.