Upconversion (UC) refers to a photon-frequency amplification process in which the energy absorbed by UC media from two or more incident photons is combined and one photon with higher energy is subsequently emitted, resulting in an anti-Stokes shift. Compared to many of the industrial and academic efforts have been mainly devoted to synthesizing and/or modifying materials comprising photonic devices for its efficiency enhancement, the UC provides a more straightforward strategy to achieve the same goal, which is a utilization of solar photons that have not been used and wasted before. We herein report critical advances made on our previous triplet-triplet annihilation based-UC microcapsule systems with the overarching goal of significantly expanding potential areas of applications such as optical display, bioimaging, photocatalysis, and photovoltaics. By employing mineral oil, PtTPBP, perylene, BPEA, and BD-2 as a new UC medium, sensitizer, and acceptors, the multicolor UC emission was achieved from a monochromatic red excitation. The UC solutions were then encapsulated with rigid polymer shell using double emulsion technique produced by capillary microfluidic device for a versatile use in aqueous and dry-phase application. Anti-Stokes emission color tuning property within single microcapsule was also realized by utilizing UC core-mediated indirect activation of fluorophore that is selectively embedded in the microcapsule shell and subsequent control of shell thickness. Finally, superparamagnetic nanoparticles were embedded to the shell for collection after use or facile color separation.

Red-to-VIS upconversion microcapsules with aqueous- and dry-phase color tuning and separation properties

247th National Meeting (2014)

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