Hybrid halide perovskites have emerged as promising active constituents of next generation solution processable optoelectronic devices. During their assembling process, perovskite components undergo very complex dynamic equilibria starting in solution and progressing throughout film formation. Finding a methodology to control and affect these equilibria, responsible for the unique morphological diversity observed in perovskite films, constitutes a fundamental step towards a reproducible material processability. Here we propose the exploitation of polymer matrices as cooperative assembling components of novel perovskite CH3NH3PbI3 : polymer composites, in which the control of the chemical interactions in solution allows a predictable tuning of the final film morphology. We reveal that the nature of the interactions between perovskite precursors and polymer functional groups, probed by Nuclear Magnetic Resonance (NMR) spectroscopy and Dynamic Light Scattering (DLS) techniques, allows the control of aggregates in solution whose characteristics are strictly maintained in the solid film, and permits the formation of nanostructures that are inaccessible to conventional perovskite depositions. These results demonstrate how the fundamental chemistry of perovskite precursors in solution has a paramount influence on controlling and monitoring the final morphology of CH3NH3PbI3 (MAPbI3) thin films, foreseeing the possibility of designing perovskite : polymer composites targeting diverse optoelectronic applications.
This chapter will describe the general features and main categories of chiral solvating agents (CSAs) for NMR spectroscopy, spanning from low-medium sized CSAs to macrocyclic ones. CSAs based on chiral ionic liquids (CILs) will be introduced in view of their increasing popularity, and, finally, a short paragraph will be dedicated to special applications of CSAs in particular experimental conditions. Several valuable works, which are mainly devoted to investigate enantiodifferentiation mechanisms by NMR, will not be discussed. The main objective is to identify the current trend in the research areas dedicated to the development of new CSAs for NMR spectroscopy.
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