Single-Component Upconverting Polymeric Nanoparticles

Abstract

Low-power light upconversion is a highly desirable feature for a broad range of applications and new materials enabling this process are sought in both bulk and particulate form. Here, the preparation of upconverting nanoparticles is reported from a methacrylic terpolymer bearing diphenylanthracene and meso-phenoxytris(heptyl)porphyrin pendant groups by a microemulsion technique. The use of a terpolymer in which the upconvering dye molecules are covalently attached mitigates some of the drawbacks of triplet-triplet annihilation upconverting nanoparticles made by other techniques, in particular dye leakage from the nanoparticles, and limited control of the sensitizer and emitter concentration within each nanoparticle. Size and morphology of the new upconverting nanoparticles are investigated by dynamic light scattering and transmission electron microscopy and elucidated their upconverting properties by luminescence spectroscopy.

Near-Infrared-to-Visible Photon Upconversion Sensitized by a Metal Complex with Spin-Forbidden yet Strong S0–T1 Absorption

“…We prepared D1 -doped rubrene nanoparticles (NPs) by the reprecipitation method. ,, A 5 mL THF solution containing D1 (0.02 mM) and rubrene (5 mM) was rapidly injected into 25 mL of sodium dodecyl sulfate (SDS) aqueous solution (10 mM), and the formed solid particles were collected by centrifugation (see SI for more details). Absorption measurements after dissolving the precipitates in DCM showed that the initial concentration ratio in THF ([ D1 ]:[rubrene] = 1:250) was almost maintained in the NPs ( D1 :rubrene = 1:270).…”

Thermoresponsive low-power light upconverting polymer nanoparticles

“…7,8 Recently, high concentrations of sTTA-UC chromophores were introduced into polymers by covalent attachment. 13,17,18 This strategy prevents phase separation and enables exciton migration, and remained largely unexploited for the design of nanoobjects. We here report sTTA-UC polymer nanoparticles that utilize this approach and display an unprecedented quantum yield of ~ 7.5% as well as strongly temperature-dependent sTTA-UC characteristics.…”

“…1,2 After attracting renewed interest in the last decade, [3][4][5][6] sTTA-UC was eventually also realized in polymers and nanoobjects. [7][8][9][10][11][12][13][14][15] The latter are thought to be useful for applications such as bio-imaging, photo-triggered drug release, oxygen sensing, and photo-chemical reactions. 11,14,15 The sTTA-UC process is based on the interplay between two chromophores, a sensitizer that absorbs light and after intersystem crossing transfers the exciton to an emitter via triplet-triplet (Dexter) energy transfer.…”

Annihilator dimers enhance triplet fusion upconversion

“…While much focus has been given to improving the sensitizer, comparatively little work has been done on the annihilator 18,19. Novel and exciting methods focusing on the structure of the materials to assemble the annihilators have been explored by the Simon and Kimizuka groups 20–22. But to date, there has been very little work to modify the annihilator itself to intrinsically enhance upconversion, especially operating at low concentrations in solution.…”