Solution-processable three-dimensionally macroporous KTiOPO4/SiO2 inverse opal powders with enhanced second harmonic emission

Three-dimensionally ordered macroporous (3DOM) KTiOPO4-based inverse opal powders have been synthesized by designing a nanocrystals-glass composite. These 3DOM nano-glass-ceramics consisting of KTiOPO4 (KTP) nanocrystals and glassy SiO2 were prepared with polymethylmethacrylate (PMMA) colloidal crystal arrays as a template and sol-gel process followed by controlled in-situ crystallization. The 60KTP/40SiO2 inverse opal powders exhibits strong second harmonic generation (SHG) observed by human naked eyes. Compared with the bulk nano-glass-ceramics, an enhanced SHG is observed from KTP/SiO2 inverse opal powders. This property may make these porous SHG emission systems for drug delivery and bioimaging in nanomedicine. The developed method can be easily adapted to other photoluminescence ions and nanocrystals to develop new multifunctional KTiOPO4-based inverse opal nanoprobes by element doping.