We studied photoluminescence (PL) properties and nonlinear absorption characteristics of heavily Cu-doped CdSe colloidal quantum dots (QDs) under nanosecond laser pulse excitation. A strong dependence of basic exciton transition behavior and Cu dopant-associated PL on the concentration of copper ions and pump intensities was revealed for the first time. The saturation of the copper-associated PL signal was found to happen much faster than the saturation of nonlinear absorption. The induced absorption and saturation of high energy transitions due to the exciton−exciton interaction were investigated in Cu-doped CdSe QDs. The obtained results could be useful for the development of optoelectronic devices operating at room temperature on the basis of Cu-doped colloidal QDs.
We report the synthesis of colloidal CdSe quantum dots doped with a novel Ag precursor: AgCl. The addition of AgCl causes dramatic changes in the morphology of synthesized nanocrystals from spherical nanoparticles to tetrapods and finally to large ellipsoidal nanoparticles. Ellipsoidal nanoparticles possess an intensive near-IR photoluminescence ranging up to 0.9 eV (ca. 1400 nm). In this article, we explain the reasons for the formation of the ellipsoidal nanoparticles as well as the peculiarities of the process. The structure, Ag content, and optical properties of quantum dots are also investigated. The optimal conditions for maximizing both the reaction yield and IR photoluminescence quantum yield are found.
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