Robust shell passivation of CdSe colloidal quantum dots to stabilize radioluminescence emission

Abstract

Systematic characterization of semiconductor colloidal quantum dots (cQDs) response to ionizing radiation must be performed to use them in radiation detection. In this study, the robustness of multi-shell (MS) and core/shell (CS) cQDs was investigated under irradiation. Radioluminescence (RL) measurements with kV and MV photon beams revealed a better resistance of MS cQDs to ionizing radiation, with their spectra fluctuating by barely ∼ 1 nm. A systematic signal recovery between subsequent irradiations was noticed for MS cQDs only. A beam energy dependence of the RL stability was detected between kV and MV energies. At the same point of dose cumulated, the RL signal loss for the kV beams was observed to be ∼6-7% smaller than that of the MV beam, for both types of cQDs. These results demonstrate that MS cQDs are better candidates as ionizing radiation sensors than CS cQDs, especially in the kV energy range.

Needs, Trends, and Advances in Inorganic Scintillators

“…Furthermore, embedding of Q-dots of direct gap semiconductors into a suitable transparent host can give rise to bulk scintillators with limited reabsorption and superfast scintillation response [124]. Note that radiation hardness has been improved using core-shell architectures [128]. Out of the scintillation field, it has been demonstrated that bulky materials, such as aerogel, superlatices, and even mixture of QDs and lead based-perovskite, can be prepared [129]- [131].…”

Dosimetric properties of colloidal quantum dot-based systems for scintillation dosimetry

“…The cQD concentration of the solutions was approximately 22 µm. A detailed description of the cQD synthetic methods and dispersion in solvents can be found elsewhere (Lecavalier et al 2013, Delage et al 2016. Two types of dosimeter were tested: a plastic optical fiber, Eska GH-4001 (Industrial Fiber Optics, Tempe, USA) coupled to the cQD powder, as has been described previously (Delage et al 2016) and the other was the cQD liquid dispersions contained in glass recipients.…”

“…This linearity holds over a clinically relevant dose range representative of an intra-fraction external beam therapy measurement (EBRT) (∼2 Gy). Furthermore, the dosimeters have previously shown potential for keeping this signal proportionality over higher dose values without saturation in light signal (Delage et al 2016).…”

“…Nanocrystals composed of ZnS:Mn 2+ have been characterized regarding their energy quantum efficiency, and their absolute efficiency under UV and x-ray irradiation, aiming for an application in x-ray detection (Saatsakis et al 2017). As for dosimetry applications, CdSe-based cQD powder and liquid dispersion detectors have been characterized regarding their robustness to radiation damage (Baharin et al 2012, Delage et al 2016, and CdSe liquid dispersions, regarding their response to irradiation by radioactive gamma sources (Lecavalier et al 2013). Another work investigated the scintillation intensity and the spectral response of CdSe-based cQD liquid dipersions under linac photon beam irradiation (Delage et al 2018).…”

Light-Generating CdSe/CdS Colloidal Quantum Dot-Doped Plastic Optical Fibers

“…One could argue that historically the first quantum-confining nanocrystals were made by melting both glass and semiconductor precursors at high temperature, − nucleating quantum dots throughout the glass structure, and hence naturally yielding preforms for the first category of nanocomposite optical fibers. − This glass melt-quenching method does not allow for elaborate control of the nanocrystal surface passivation, , thus defects degrade the PL emission, creating further challenges to control the density of nanocrystals and their size distribution. − A second category of debatably nanocomposite fibers thus recently emerged: doping optical fibers with cQDs using a number of postprocessing techniques, such as filling hollow core fibers with a liquid containing cQDs − and coating the core of microstructured optical fibers − or fiber tapers and ends. − These techniques seem a priori advantageous in their chemical simplicity and flexibility, benefiting from the separate synthesis of cQDs under well controlled conditions enabling passivation with heterostructures of multiple semiconductor shells , and even with further surface ligand exchange afterward. ,, However, the lack of stability and robustness coupled with high optical losses in the cQD host solvents limits the practicality of liquid core fibers, with the added drawback of air exposure when the solvent evaporates, causing surface chemical reactions that increase photobleaching and photoactivation.…”