A research team from the University of Groningen, led by Jan C. Hummelen, has developed a method for broadband dye-sensitized upconversion of near-infrared (NIR) light. The study, published in Nature Photonics, demonstrates the efficient conversion of NIR light into visible light using a combination of dye molecules and nanoparticles. The key components of the system are IR-806 dye molecules and NaYF4:Yb,Er nanoparticles, which are functionalized with IR-806 to enhance light absorption and energy transfer. The dye molecules act as sensitizers, absorbing NIR light and transferring the energy to the nanoparticles, which then upconvert the energy into visible light through the presence of Yb and Er ions. The study shows that the system achieves a high quantum yield, with the maximum monochromatic quantum yield (mQY) of IR-806/NPs reaching 0.12±0.10%. The results indicate that the energy transfer efficiency from the dye to the nanoparticles is approximately 50%, which is crucial for the efficient upconversion process. The research provides a promising approach for applications in optical communication, imaging, and sensing technologies. The study also includes detailed experimental procedures, spectroscopic and microscopic data, and calculations of molecular weight, antenna-to-nanoparticle ratios, and intermolecular distances. The findings highlight the potential of dye-sensitized upconversion for broadband NIR light conversion into visible light, with significant implications for future photonic and optoelectronic applications.A research team from the University of Groningen, led by Jan C. Hummelen, has developed a method for broadband dye-sensitized upconversion of near-infrared (NIR) light. The study, published in Nature Photonics, demonstrates the efficient conversion of NIR light into visible light using a combination of dye molecules and nanoparticles. The key components of the system are IR-806 dye molecules and NaYF4:Yb,Er nanoparticles, which are functionalized with IR-806 to enhance light absorption and energy transfer. The dye molecules act as sensitizers, absorbing NIR light and transferring the energy to the nanoparticles, which then upconvert the energy into visible light through the presence of Yb and Er ions. The study shows that the system achieves a high quantum yield, with the maximum monochromatic quantum yield (mQY) of IR-806/NPs reaching 0.12±0.10%. The results indicate that the energy transfer efficiency from the dye to the nanoparticles is approximately 50%, which is crucial for the efficient upconversion process. The research provides a promising approach for applications in optical communication, imaging, and sensing technologies. The study also includes detailed experimental procedures, spectroscopic and microscopic data, and calculations of molecular weight, antenna-to-nanoparticle ratios, and intermolecular distances. The findings highlight the potential of dye-sensitized upconversion for broadband NIR light conversion into visible light, with significant implications for future photonic and optoelectronic applications.