Nonlinear Optical Properties of Emerging Nano‐ and Microcrystalline Materials

Abstract

The activity in the research on novel optical materials exhibiting nonlinear optical (NLO) properties is surveyed, especially nonlinear absorption, that may be attractive for various applications, including those in optoelectronics, photonics, and biophotonics. The recently introduced concept of “NLO pigments”—insoluble colored materials that can exhibit useful NLO effects—is demonstrated to apply to the multifunctional group of coordination polymers (CPs) and their subgroup of metal‐organic frameworks (MOFs), which may be applied in their microcrystalline form or as nanoparticles. Nanocrystalline materials such as semiconductor quantum dots or plasmonic particles made of noble metals have been widely studied and their properties have been often reviewed, thus they are not included in this review. On the other hand, studies performed on perovskites are described: materials that appear to have great potential for NLO applications in addition to their well‐known merit in photovoltaics. There is also much activity in the field of low‐dimensional, especially 2D structures of various kinds, and this review covers many examples of such structures, not including the broad topic of carbon nanostructures (graphene, nanotubes etc.) but concentrating on other emerging nonlinear optical materials such as black phosphorus, transition metal dichalcogenides, MXenes, and topological insulators.

Recent advances of multiphoton absorption in metal–organic frameworks

“…18 Furthermore, this growth is underpinned by the number of publications per year, starting in 2005 with the successful synthesis of a NLO active coordination polymer by Chen et al, ending up with 19 publications in 2021 and Since our initial review article published in 2017, 18 the amount of nonlinear absorbing CPs has continuously increased and with that the gained knowledge about this fascinating class of materials. In 2021 Zareba et al 21 published a review article with the focus on microcrystalline materials, highlighting MOFs, perovskites and the physics behind their non-linear optics. The purpose of our article is to review in this rapidly developing research area with a focus on mechanistic studies, spectroscopic methods and research examples where MPA active CPs or MOFs have been explicitly applied.…”

Much of a Muchness: On the Origins of Two- and Three-Photon Absorption Activity of Dipolar Y-Shaped Chromophores

“… 20 , 21 However, the focus has now shifted toward metal–organic frameworks, perovskites, and materials with reduced dimensionality (particularly 2D materials). 22 − 25 Although 3PA-based imaging promises to be a robust competitor to known 2PA techniques, 3PA processes are still much less explored than 2PA phenomena, on both the experimental and theoretical side. It stems from the challenges of experimental measurements of multiphoton effects, as the probability of simultaneous absorption of three and more photons is much smaller than that in the 2PA process.…”

Structural transformation of copper coordination complexes accompanied with chiral transformation

“…28,[35][36][37][38][39][40][41] Chirality is also a universal feature in nature and living organisms, and chiral complexes show unique properties including circular dichroism (CD), circularly polarized luminescence (CPL), optical rotation, chiroptical switching processes, and nonlinear optical (NLO) activity. [42][43][44][45][46][47][48] When structural transformation meets chirality, the generation, reversal and disappearance of chiral structures is of considerable interest. [49][50][51] Structural transformation involving chiral properties is very significant due to the polarity elimination trend in molecular packing, which provides a perfect platform to research the dissociation and formation of chiral structures.…”