Lead halide perovskites have drawn extensive attention over recent decades owing to their outstanding photoelectric performances. However, their toxicity and instability are big issues that need to be solved for further commercialization. Herein, we adopt a facile dry ball milling method to synthesize lead-free Cs 3 Cu 2 X 5 ( X = I , Cl) perovskites with photoluminescence (PL) quantum yield up to 60%. The optical features including broad emission spectrum, large Stokes shift, and long PL lifetime can be attributed to self-trapped exciton recombination. The as-synthesized blue emissive Cs 3 Cu 2 I 5 and green emissive Cs 3 Cu 2 Cl 5 lead-free perovskite powders have good thermal stability and photostability. Furthermore, UV-pumped phosphor-converted light-emitting diodes were obtained by using Cs 3 Cu 2 I 5 and Cs 3 Cu 2 Cl 5 as phosphors.

Single-walled carbon nanotubes (SWNTs) with high covalent bonding density of polymer layers have been prepared by a "grafting to" approach, where the benzyl chloride groups of styrene copolymers (M n ) 47 600) reacted with the alkyne groups on SWNTs under relatively mild conditions, resulting in a higher grafting efficiency, as high as 81 wt % of (TGA). Microscopic observations clearly displayed the uniform, thick polymer layers formed on the SWNT surface. The high density of covalent bonding between polymer and nanotubes was confirmed by Raman, 1 H NMR, and FTIR, which makes them well dissolved in organic solvents and homogeneously dispersed in polymer matrices. The in situ UV-vis observations during the dissolution indicated that for such a multifunctional system almost no cross-links occurred between SWNTs due to the physical absorption and steric hindrance of polymer chains during the functionalization of SWNTs. The functionalized SWNTs exhibited a pronounced effect on the mechanical properties of polystyrene composites. Only 0.06 wt % of SWNTs resulted in 82% and 78% of increases in tensile strength and elastic modulus of the composites, respectively, indicating an efficient interfacial stress transfer between SWNTs and polymer.

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These figures show that the cyclodextrin polymer was synthesized successfully and possessed good thermal stability.

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