Recent studies demonstrated that the formation of a core/shell structure can largely enhance the chemical, thermal, and photochemical stability of QDs, thanks to the ability of the shell to passivate the core, by removing defects/traps, preserving it from oxidation. 1–3 Such systems have already demonstrated their potential in various applications, including light-emitting diodes, photodetectors, excitonic solar cells, biomedical labeling, nanothermometers and photocatalysis.
Introduction Colloidal quantum dots (QDs) are very attractive nanoscale systems due to the possibility of controlling their optical and electronic properties by tuning their size and shape. These results highlight the importance of the driving force leading to preferential crystal growth in asymmetric QDs, and provide a pathway for the rational control of the synthesis of double color emitting giant QDs, leading to the effective exploitation of visible/NIR transparency windows. We show that the double emission depends on the excitation condition and analyze the electron–hole distribution responsible for the independent and simultaneous radiative exciton recombination in the PbS core and in the CdS Wz shell, respectively. We present the synthesis of giant core/shell/shell asymmetric QDs having a PbS/CdS zinc blende (Zb)/CdS wurtzite (Wz) structure with double color emission close to the near-infrared (NIR) region. In this context, quantum dots (QDs) with double color emission may represent ultra-accurate and self-calibrating nanosystems.
#Imoto strada windows#
E-mail: nanocrystals optically active in the infrared region of the electromagnetic spectrum enable exciting avenues in fundamental research and novel applications compatible with the infrared transparency windows of biosystems such as chemical and biological optical sensing, including nanoscale thermometry. China g Center for Self-Assembled Chemical Structures, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada h Dipartimento di Energia, IFN-CNR, Politecnico di Milano, via Ponzio 34/3, 20133 Milano, Italy i Department of Engineering Sciences and Mathematics, Luleå University of Technology, 971 98 Luleå, Sweden.
da Vinci 32, 20133 Milano, Italy d CNR-IMM Sezione di Bologna, Via Gobetti 101, 40129 Bologna, Italy e CNR-IMM Sezione di Catania, Strada VIII, 5, 95121 Catania, Italy f Institute for Fundamental and Frontier Science University of Electronic Science and Technology of China, Chengdu 610054, P.R. E-mail: c Dipartimento di Fisica, Politecnico di Milano, piazza L. * bi a CNR-INO SENSOR Lab, Via Branze 45, 25123 Brescia, Italy b Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada. Nanoscale, 2016, 8, 4217-4226 Dual emission in asymmetric “giant” PbS/CdS/CdS core/shell/shell quantum dots †
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