Boosting Dye-Sensitized Luminescence by Enhanced Short-Range Triplet Energy Transfer.

Dye-sensitization can enhance lanthanide-based upconversion luminescence, but is hindered by interfacial energy transfer from organic dye to lanthanide ion Yb 3+ . To overcome these limitations, we propose modifying coordination sites on dye conjugated structures and minimizing the distance between fluorescence cores and Yb 3+ in upconversion nanoparticles (UCNPs). Our specially designed near-infrared (NIR) dye, disulfo-indocyanine green (disulfo-ICG), acts as the antenna molecule and exhibits a 2413-fold increase in luminescence under 808 nm excitation compared to UCNPs alone using 980 nm irradiation. The significant improvement is attributed to the high energy transfer efficiency of 72.1% from disulfo-ICG to Yb 3+ in UCNPs, with majority of energy originating from triplet state (T 1 ) of disulfo-ICG. Shortening the distance between the dye and lanthanide ions increases the probability of energy transfer and strengthens the heavy atom effect, leading to enhanced T 1 generation and improved dye-triplet sensitization upconversion. Importantly, this approach also applies to 730 nm excitation Cy7-SO 3 sensitization system, overcoming the spectral mismatch between Cy7 and Yb 3+ and achieving a 52-fold enhancement in luminescence. Furthermore, we demonstrate the enhancement of upconversion at single particle level through dye-sensitization. This strategy expands the range of NIR dyes for sensitization and opens new avenues for highly efficient dye-sensitized upconversion systems. This article is protected by copyright. All rights reserved.