Optical Properties and Applications of Crystalline Materials

Abstract

Recent years have witnessed the prosperous developments of crystalline materials based on diverse organic/inorganic small molecules, metal organic frameworks (MOFs), covalent organic frameworks (COFs), etc. Crystalline materials are highly attractive for their highly ordered molecular and supramolecular architectures, allowing for the rational design of materials with brilliant optical properties and advanced photonic applications. In particular, crystalline materials often feature well-defined morphologies in wavelength and subwavelength scales, and are therefore ideal platforms for the realization of many advanced optical functionalities such as waveguiding, lasing, and optical logics. In recognition of the importance of this field, we have gladly taken the opportunity to serve as the Guest Editors to organize this themed special issue, with the aim to highlight the state of the art in the area of crystalline materials for optical applications. This special issue, consisting of 14 reviews and 6 research papers, covers a broad spectrum of the recent advances in crystalline optical materials based on MOFs, COFs, perovskites, microporous zeolites, and small molecules. It encompasses some of the highly important research achievements, efforts and practices of crystalline materials in many well-established optical applications including light emitting diodes (LEDs), waveguides, optical sensing, nonlinear optics (NLO), as well as the emerging photonic technologies such as terahertz (THz) generation and detection. MOFs are crystalline materials assembled by the coordination interactions between metal-containing nodes and organic linkers. Luminescent MOFs, with diversified architectures, devisable pore structures and affluent luminescence, provide great potential for the development of novel phosphors. In their review article, Prof. Guodong Qian and co-workers focus on the phosphor-converted white LEDs based on MOF matrixes doped with luminescent lanthanide ions, organic ligands, and/or encapsulated with diverse luminescent guest species including organic dyes, metal complexes, quantum dots (adom.202001817). In terms of luminescent species encapsulated host–guest MOFs, Prof. Xian-He Bu and co-workers provide a comprehensive review on the construction strategies and optical applications of luminescent particles hybridized MOFs materials (adom.202100283). Similar encapsulation strategy can be applied in other porous materials. Dr. Eduardo Coutino-Gonzalez and colleagues present the tunable luminescence behaviours from stable silver nanoclusters confined in microporous zeolites (adom.202100526). Many fascinating optical effects and proccesses have been explored in MOF materials. In their review article, Prof. Shuang-Quan Zang et al. discuss on MOF materials with thermally activated delayed fluorescence (TADF) properties (adom.202100081). The TADF characteristics of metal–organic complexes, organic ligand-protected metal clusters, and coordination polymers have been summarized. Prof. Mei Pan and colleagues present an overview on another highly important optical process, namely the excited-state intramolecular proton transfer (ESIPT), in the solid-state materials including MOFs, COFs, and small organic molecules (adom.202001952). In their research article, Prof. Dan Li, Prof. Xiao-Ping Zhou, et al. present a strategy to turn-on the circularly polarized luminescence in a family of homochiral MOF materials constructed by conformation tuning of ligands and self-assembly control (adom.202002096). Lead halide perovskites have recently emerged as highly promising optoelectronic materials owing to their low-cost solution fabrication, chemical versatility, tolerance to defects, large absorption coefficient, and high charge carrier mobility. Prof. Zhang Chuang and colleagues present a review to summarize the recent progress on (linearly and circularly) polarized photoluminescence from lead halide perovskites (adom.202002236). In their research article, Prof. Wei Li, Prof. Xiang Wu, Prof. Xian-He Bu, et al. report on thermal and pressure dual-stimuli-responsive luminescence of a pair of new enantiomeric 2D Dion–Jacobson hybrid organic–inorganic perovskites (adom.202100003). Meanwhile, Dr. Elke Debroye, Prof. Johan Hofkens, et al. provide experimental evidence of chloride induced trap passivation in lead halide perovskites through single particle blinking studies (adom202002240). On the other hand, Dr. Valentin Diez-Cabanes, Prof. David Beljonne, et al. studied from the theoretical point of view the electronic structures and optical properties of mixed iodine/bromine lead perovskites (adom.202001832). Lead halide perovskites have been also widely applied in NLO. In this aspect, Prof. Wei Ji, Prof. Shunbin Lu and colleagues present a comprehensive review on multiphoton absorption properties and applications of perovskite materials (adom.202100292). In another review article, Prof. Marek Samoć and co-workers introduce the concept of “NLO pigments” based on different nano- and microcrystalline materials including MOFs, perovskites, 0D/1D materials, as well as 2D structures such as black phosphorus, transition metal dichalcogenides, MXenes, and topological insulators (adom.202100216). Other NLO materials such as molecular materials based on small organic compounds have been also explored. Prof. Theo Rasing and colleagues show their particular interest in a family of fluorenone based molecular materials (adom.202100327), while Dr. Mojca Jazbinsek, Prof. Fabian Rotermund, Prof. O-Pil Kwon, et al. shed light on the terahertz wave generation, detection, and applications of some highly efficient NLO organic crystals (adom.202101019). Many more optical and photonic functionalities have been realized in small molecule based crystalline materials other than NLO. Prof. Dongpeng Yan and colleagues introduce the recent advances on molecular crystalline luminescent materials for optical waveguides (adom.202001768), while Prof. Yulan Chen and colleagues pay special attention to the waveguide behaviours of polycyclic arenes based organic crystals (adom.202002264). Prof. Akimitsu Narita et al. provide an overview of the latest developments in the chemical synthesis and spectroscopic investigations of atomically precise graphene quantum dots based on polycyclic aromatic hydrocarbons and their applications in lasing and optical imaging (adom.202100508). Prof. Yang Zhang et al. present the recent advances in the field of optical control over ferroelectric polarization in various ferroelectrics including oxide perovskites, van der Waals ferroelectrics, and ferroelectric heterostructures (adom.202002146). In their research article, Prof. Giancarlo Morelli, Prof. Gil Rosenman, et al. observe a type of fold-sensitive visible fluorescence in both biological amyloid and bioinspired amyloidogenic assemblies, arising at the earliest stages of seeding and nucleation of β-sheet nanofibers (adom.202002247). Prof. Jing Liu, Prof. Joseph M. K. Irudayaraj, Prof. Gary J. Cheng, et al. realized enhanced energy transfer from nitrogen-vacancy centers to three-dimensional graphene heterostructures by laser nanoshaping (adom.202001830). This themed special issue might not be exhaustive, but it highlights some of the recent advances in the optical properties and applications of crystalline materials. We hope that the special issue will provide a timely, meaningful and valuable reference and perspective for the research community in this important field. We would like to thank Dr. Anja Wecker (Editor-in-Chief) and Dr. Jipei Yuan (Deputy Editor) for giving us the opportunity to organize this special issue. Our appreciation extends to the editorial team of Advanced Optical Materials, for their professionalism throughout the editing process. We are also very grateful to all the contributing authors for their efforts and enthusiastic support. Jialiang Xu is a Professor of Materials Chemistry at Nankai University. He obtained his PhD from ICCAS in 2010 under the supervision of Prof. Yuliang Li, and then worked as Marie-Curie Fellow at Radboud University, Nijmegen. In 2013, he was awarded the NWO-VENI grant, with which he developed his research line at the interface between chemistry and physics to study the coupling between light and (supra)molecular materials. He joined Tianjin University in 2015, and relocated to Nankai University in 2018. Xian-He Bu is a Cheung Kong Scholar Professor of Chemistry at Nankai University (from 2004). He obtained his BS and PhD degrees from Nankai University in 1986 and 1992 under the supervision of Prof. Rong-Ti Chen. Since 1995, he has been a full professor at Nankai University. He now serves as the dean of School of Material Science and Engineering, and a director of Tianjin Key Lab of Metal and Molecule-Based Material Chemistry. His current research focuses on the syntheses and applications of multifunctional coordination compounds, crystal engineering, magnetic materials, etc.