< Back to previous page

Publication

From molecular complexes to a 'molecule on a particle' approach for optical amplification in the NIR

Book Contribution - Book Abstract Conference Contribution

Energy-efficient light amplification in the near-infrared (NIR) wavelength range (800 nm-1.6 µm) is currently one of the major challenges in photonic technologies at the heart of novel highly performing global telecommunication systems. NIR-emitting lanthanide ions (Ln), especially the triad Er3+, Yb3+, Nd3+, play a special role in this context in view of their unique emissive properties which originate from parity-forbidden intra-atomic 4f-4f transitions delivering long-lived luminescence with high color-purity. However, the very weak intrinsic absorption cross-section of these emitters demands high pump powers for direct photoexcitation to achieve acceptable optical gain coefficients in photonic devices, in turn leading to high energy consumption in optical links. For this reason, Ln molecular complexes with organic ‘antenna’ ligands, which enable highly efficient indirect photoexcitation of the Ln emitter, have become very popular in the last two decades. Such molecular frameworks also enable fully efficient interlanthanide communication and heterolanthanide-mediated antenna energy transfer in polynuclear assemblies thanks to shortly-separated and spatially defined donor-acceptor sites. However these materials typically display low Ln emission quantum yields due to phonon quenching related to the CH, NH, or OH groups native of the organic moiety. A “hybrid” organic-inorganic approach can be proposed as a smart strategy to achieve complex-like photosensitization of a Ln emitter, without the organics-mediated phonon quenching. In the so-designed hybrid organic-inorganic nanomaterials, Ln-ions are embedded into a low-phonon purely inorganic core-shell nanoparticle, which is surface-grafted with an organic 'antenna' chromophore enabling indirect photosensitization of the Ln emitter. Multilayered nanoparticle architectures allow the confinement of donor-acceptor pairs into thickness-controlled shells leading to sensitization efficiencies comparable to those achievable in molecular complexes (almost unitary) and exceptionally high NIR emission intensities. At the same time, the low phonon environment provided by the inorganic matrix allows for unusually long (in the hundreds of µs – ms range) NIR emission lifetimes. These hybrid organic-inorganic nanoarchitectures combine the efficient light harvesting properties typical of Ln molecular complexes with long-lived excited state lifetimes of Er3+, Yb3+ and Nd3+ ions within an inorganic core and hold significant potential for achieving optical amplification in the NIR.
Book: f-Elements, 10th International conference, Abstracts
Number of pages: 1
Publication year:2018