scholarly journals Interfaces in metal halide perovskites probed by solid-state NMR spectroscopy

Author(s):  
Clayton J. Dahlman ◽  
Dominik J. Kubicki ◽  
G. N. Manjunatha Reddy

Metal halide perovskites (MHPs) are promising light harvesting and emitting materials that have enabled solar energy conversion efficiencies of over 25% in solution-processed single-junction cells, and found applications in flexible...

2020 ◽  
Author(s):  
Jeongjae Lee ◽  
Woocheol Lee ◽  
Keehoon Kang ◽  
Takhee Lee ◽  
Sung Keun Lee

Application of two-dimensional (2D) organic-inorganic hybrid halide perovskites for optoelectronic devices requires detailed understanding of the local structural features including the Pb-I bonding in the 2D layers and the capping ligand-perovskite interaction. In this study, we show that <sup>1</sup>H and <sup>207</sup>Pb solid-state Nuclear Magnetic Resonance (NMR) spectroscopy can serve as a non-invasive and complementary technique to quantify the composition and to probe the local structural features of 2D Ruddlesden-Popper phase BA<sub>2</sub>MA<i><sub>n</sub></i><sub>-1</sub>Pb<i><sub>n</sub></i>I<sub>3<i>n</i>+1</sub> (<i>n</i>=1-4) with butylammonium (BA) spacers. <sup>207</sup>Pb echo and <sup>1</sup>H-detected <sup>207</sup>Pb→<sup>1</sup>H heteronuclear correlation (HETCOR) experiments enables layer-by-layer structural detection of 2D halide perovskites. We show that the observed correlation between <sup>207</sup>Pb NMR shifts and mean Pb-I bond lengths around each Pb site allows us to probe the local bonding environment of Pb via its <sup>207</sup>Pb NMR shift. We envisage that this technique will be vital for better understanding the materials properties as determined by the local atomistic environments in multi-dimensional halide perovskites.


2020 ◽  
Author(s):  
Jeongjae Lee ◽  
Woocheol Lee ◽  
Keehoon Kang ◽  
Takhee Lee ◽  
Sung Keun Lee

Application of two-dimensional (2D) organic-inorganic hybrid halide perovskites for optoelectronic devices requires detailed understanding of the local structural features including the Pb-I bonding in the 2D layers and the capping ligand-perovskite interaction. In this study, we show that <sup>1</sup>H and <sup>207</sup>Pb solid-state Nuclear Magnetic Resonance (NMR) spectroscopy can serve as a non-invasive and complementary technique to quantify the composition and to probe the local structural features of 2D Ruddlesden-Popper phase BA<sub>2</sub>MA<i><sub>n</sub></i><sub>-1</sub>Pb<i><sub>n</sub></i>I<sub>3<i>n</i>+1</sub> (<i>n</i>=1-4) with butylammonium (BA) spacers. <sup>207</sup>Pb echo and <sup>1</sup>H-detected <sup>207</sup>Pb→<sup>1</sup>H heteronuclear correlation (HETCOR) experiments enables layer-by-layer structural detection of 2D halide perovskites. We show that the observed correlation between <sup>207</sup>Pb NMR shifts and mean Pb-I bond lengths around each Pb site allows us to probe the local bonding environment of Pb via its <sup>207</sup>Pb NMR shift. We envisage that this technique will be vital for better understanding the materials properties as determined by the local atomistic environments in multi-dimensional halide perovskites.


2021 ◽  
Vol 11 (13) ◽  
pp. 5767
Author(s):  
Veronica Ciaramitaro ◽  
Alberto Spinella ◽  
Francesco Armetta ◽  
Roberto Scaffaro ◽  
Emmanuel Fortunato Gulino ◽  
...  

Hydrophobic treatment is one of the most important interventions usually carried out for the conservation of stone artefacts and monuments. The study here reported aims to answer a general question about how two polymers confer different protective performance. Two fluorinated-based polymer formulates applied on samples of Cusa’s stone confer a different level of water repellence and water vapour permeability. The observed protection action is here explained on the basis of chemico-physical interactions. The distribution of the polymer in the pore network was investigated using scanning electron microscopy and X-ray microscopy. The interactions between the stone substrate and the protective agents were investigated by means of solid state NMR spectroscopy. The ss-NMR findings reveal no significant changes in the chemical neighbourhood of the observed nuclei of each protective agent when applied onto the stone surface and provide information on the changes in the organization and dynamics of the studied systems, as well as on the mobility of polymer chains. This allowed us to explain the different macroscopic behaviours provided by each protective agent to the stone substrate.


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