Controlled synthesis of high quality scandium-based nanocrystals as promising recyclable catalysts for silylcyanation reaction.

High quality (monodisperse and well-defined) scandium based ternary fluoride nanocrystals of NaScF4 and KSc2F7 were successfully fabricated via a one-pot colloidal synthesis method. These nanocrystals can play the part of hard Lewis acid catalysts by providing Lewis acid sites on account of the unique electronic structure, i.e. the ability of polarizing double bonds by coordination. As a proof of concept application, NaScF4 and KSc2F7 nanocatalysts were used to catalyze the silylcyanation reaction at room temperature, which exhibited excellent catalytic activity with outstanding recyclability.

Enhanced conversion efficiency in perovskite solar cells by effectively utilizing near infrared light.

Up-conversion ß-NaYF4:Yb(3+),Tm(3+)/NaYF4 core-shell nanoparticles (NYF NPs) with a high luminous intensity in the visible light region were synthesized by a hydrothermal reaction process. Photocurrent densities of the mesoscopic perovskite solar cells fabricated by incorporating up-conversion NYF NPs into the electron transporting layer are effectively enhanced. The effects of the thicknesses of the electron transporting layer and the weight ratio of up-conversion NYF NPs/TiO2 on the power conversion efficiency (PCE) of the as-fabricated devices were also investigated. The results indicate that the PCE of the optimized device achieves 16.9%, which is 20% higher than that of the device without introducing NYF NPs, and the steady-state PCE of the as-fabricated devices is close to its transient-state PCE. The up-conversion effect of NYF NPs is conducive to higher device performance rather than the nanoparticles as scattering centers to increase possible light absorption of the perovskite film or the electronic effect of the NaYF4 shell surface. These results can be further confirmed by finite-difference time-domain simulation. Photoluminescence results suggest that the multiphonon-assistance can accelerate the nonradiative recombination process at a lower temperature. Incorporating NYF NPs into the electron transporting layer opens a new approach to a promising family of electron transporting materials for mesoscopic perovskite solar cells.