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A detailed study of nonlinear absorption parameters of two porphyrin, tetraphenylporphyrin and dithiaporphyrin diacids as well as their neutral parent complexes is demonstrated. The two diacids exhibit perturbed static and dynamic characteristics and enhanced nonlinear absorption properties which could be applied to optical limiting.

Nonlinear absorption and nonlinear refraction of self-assembled porphyrins in the nanosecond and picosecond regimes are studied at 532 nm by the Z-scan technique. An enhancement of nonlinear absorption is observed for the monomeric components of self-assembled structures by adding pyridine, while their nonlinear refractions remain almost unchanged as pyridine is added.

It is known that CH3NH3PbI3 is particularly promising for next-generation solar devices; therefore, molecular perovskite structures have recently received extraordinary attention from the academic community because of their potential in producing unique physical properties. However, although great efforts have been made, molecular ferroelectrics with three-dimensional (3D) perovskite structures are still rare. So far, reported perovskite-like molecular ferroelectrics are basically one- or two-dimensional, significantly deviating from the inorganic perovskite ferroelectrics. Thus, their ferroelectric properties have to be greatly improved to meet the requirements of practical applications. Here, we report a 3D molecular perovskite ferroelectric: (3-ammoniopyrrolidinium)RbBr3 [(AP)RbBr3], with a high Curie temperature (Tc = 440 K) beyond that of BaTiO3. To the best of our knowledge, such above-room-temperature ferroelectricity in the 3D molecular perovskite compound is unprecedented. Furthermore, (AP)RbBr3 has great potential for applications due to its high thermal stability, ultrafast polarization reversal (greater than 20 kHz), and fascinating multiaxial characteristic. This finding opens a new avenue to the design and controllable synthesis of molecular ferroelectric perovskites, where the metal ion, halogen ion, and organic cation can be easily tuned. [ABSTRACT FROM AUTHOR]