Vapor-and temperature-triggered reversible optical switching for multi-response Cu_(8)cluster supercrystals

Multi-response metal cluster supercrystal materials,which can simultaneously display various such as color,photoluminescence,changes by bearing only one stimulus,have huge potential as stimuliresponsive intelligent material,but are rarely reported.Here,we report three Cu_(8)cluster supercrystals,Cu_(8)-1,Cu_(8)-2,and Cu_(8)-3,with homologous cluster molecule units[Cu_(8)(PNP)_(3)(EPPTA)_(6)](PF_(6))_(2)but distinct packing.These supercrystals display brightμs-long photoluminescence with a high quantum yield of up to 26.6%in solid-state at room temperature and aggregation-induced emission(AIE)characteristic.Superior thermal stability and blue-excitable bright yellow emission make Cu_(8)-3 serve as a yellow phosphor for white light-emitting diode.Furthermore,upon being stimulated by solvent vapor and temperature,reversible supercrystal-to-supercrystal transformations can be witnessed accompanied by remarkable color and luminescence switching.This work not only provides a kind of Cu cluster supercrystal model but also motivates the further development of metal clusters in multi-response materials.

Understanding the forces acting in self-assembly and the implications for constructing three-dimensional （3D） supercrystals

The assembly of nanocrystals into ordered structures called supercrystals or superstructures has become a pivotal frontier owing to numerous useful applications such as correlating the arrangements of atoms in macroscopic crystals and tuning the collective properties to meet the demands of various applications. In this article, recent progress in the preparation of three-dimensional superlattices of nanocrystals is outlined, with a particular emphasis on the driving forces and evolutionary routes beyond orderly assembly. First, the leading or repulsive forces that internally and externally govern the formation of three-dimensional supercrystals are systematically identified and discussed with respect to their origins and functions in three-dimensional self-organization. Then a synoptic introduction of commonly applied means of nanocrystal self-assembly based on growth scenarios such as droplet evaporation and a liquid/liquid interface is presented with specific cases and detailed analyses. Finally, the existing challenges and prospects for this field are briefly highlighted.

Holographic fabrication of octagon graded photonic supercrystal and potential applications in topological photonics

Novel optical properties in graded photonic super-crystals can be further explored if new types of graded photonic super-crystals are fabricated.In this paper,we report holographic fabrication of graded photonic super-crystal with eight graded lattice clusters surrounding the central non-gradient lattices through pixel-by-pixel phase engineering in a spatial light modulator.The prospect of applications of octagon graded photonic super-crystal in topological photonics is discussed through photonic band gap engineering and coupled ring resonators.