All-inorganic colloidal upconversion quantum dots (Conference Presentation)

Dan Oron; Ayelet Teitelboim

doi:10.1117/12.2250340

24 April 2017 All-inorganic colloidal upconversion quantum dots (Conference Presentation)

Dan Oron, Ayelet Teitelboim

Proceedings Volume 10078, Colloidal Nanoparticles for Biomedical Applications XII; 1007803 (2017) https://doi.org/10.1117/12.2250340
Event: SPIE BiOS, 2017, San Francisco, California, United States

Abstract

Upconversion (UC) is a nonlinear process in which two, or more, long wavelength photons are converted to a shorter wavelength photon. This process is based on sequential absorption of two or more photons, involving metastable, long lived intermediate energy states, thus is not restricted to ultrashort pulsed excitation. Hence, requirements for UC processes are long lived excited states, a ladder like arrangement of energy levels and a mechanism inhibiting cooling of the hot charge carrier. UC holds great promise for bioimaging, enabling to perform multiphoton imaging in scattering specimen at very low powers. Rare-earth-doped nanocrystals, the most commonly used ones for UC, typically require a minimal particle diameter of several tens of nanometers and have a limited action spectrum. Here, we present a novel luminescence upconversion nano-system based on colloidal semiconductor double quantum dots, consisting of a NIR-absorbing component and a visible emitting component separated by a tunneling barrier in a spherical onion-like geometry. These dual near-infrared and visible core/shell/shell PbSe/CdSe/CdS nanocrystals are shown to efficiently upconvert a broad range of NIR wavelengths up to 1.2 microns to visible emission at room temperature, covering a spectral range where there are practically no alternative upconversion systems. The particle diameter is less than ten nanometers, and the synthesis enables versatility and tunability of both the visible emission color and the NIR absorption edge. The physical mechanism for upconversion in this type of structures, as well as potential advances and extensions on this system will be discussed.

Conference Presentation

Citation Download Citation

Dan Oron and Ayelet Teitelboim "All-inorganic colloidal upconversion quantum dots (Conference Presentation)", Proc. SPIE 10078, Colloidal Nanoparticles for Biomedical Applications XII, 1007803 (24 April 2017); https://doi.org/10.1117/12.2250340

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KEYWORDS

Upconversion

Visible radiation

Photons

Quantum dots

Absorption

Nanocrystals

Near infrared

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