Hybrid halide perovskite based solar cells have demonstrated unprecedented progress in their efficiency, leading to efficiencies of up to 22.1%, in the past six years. Moreover, their intriguing properties of high dielectric constant, wide optical absorption range, low trap density, low non-radiative recombination and photoluminescence have attracted great research interest in the fields of optoelectronic applications and photovoltaics. This review briefly outlines the frontier of the research fields of perovskite materials, and summarizes the structure and growth of hybrid perovskite single crystals. Finally, the enormous challenges and the promising outlook of these active topics are highlighted.

Lithium niobate (LiNbO3 or LN) is a well-known multifunctional crystal that has been widely applied in various areas of photonics, electronics, and optoelectronics. In the past decade, “ion-cut” has become the key technique to produce wafer-size, high-quality, sub micrometer-thickness crystalline LiNbO3 thin films, i.e., lithium-niobate-on-insulator (LNOI). With the rapid development of LNOI technology and the tremendous progress of associated surface structuring and engineering techniques over the last few years, many novel chip-integrated LiNbO3-based devices and applications with reduced cost, complexity, power, and size, are demonstrated, boosting the resurgence of integrated photonics based on this material. The remarkable achievements are largely facilitated by the most recent technological progress in photonic integration and performance optimization of LNOI on-chip devices, such as high-quality surface domain engineering, advanced heterogeneous integration technology, powerful dispersion engineering, fine polishing lithography, and wafer-scale fabrication. Accordingly, batch-compatible chip-integrated platforms for more complex photonic integrated circuits, such as quantum optical circuits, are within reach. This article provides a timely review of the key advances in LNOI technology and a reasonable perspective on the near-future directions for both integrated photonics and applied physics communities.

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Several cyclized indole derivatives have been synthesized, and their structures been determined. The C3-symmetric single-chiral N-phenyltriindole (Tr-Ph3) crystallized in the P1 space group, and the S4-symmetric saddle-like tetraindole (TTr) crystallized in the I4̅ space group. The Tr-Ph3 and TTr crystals exhibit remarkable powder SHG intensities 5 and 11 times that of KH2PO4 (KDP), respectively. TTr is a useful octupolar core to build S4-symmetric molecules and crystals for second-NLO materials.