Colloidal Quantum Dots (QDs) are an established class of optoelectronic materials thanks to their tunable and highly efficient emission. The encapsulation of QDs in silica shells is a well-known procedure to protect them from the external environment and obtain dispersibility in polar solvents. Here, we have coated different types of QDs (CdSe@CdS [1] and InP@ZnS [2]) with silica shells of controlled thickness. The silica shells were obtained exploiting the Reverse Microemulsion reaction combined with an experimental design approach [3,4]. In addition to this, we deposited a uniform gold film over the silica shell. The combination of the QDs emission with the gold plasmon resonance enables an improvement in the optical properties, as already demonstrated [5]. As a first step to achieve this goal, the functionalization of the silica shell for further gold seeds attachment is required. With such aim, we employed (3-Aminopropyl)trimethoxysilane (APTMS), with an amino group binding to the gold seed, helping in the development of the film. Instead, the silicon of the APTMS binds strongly to the silica surface through a covalent bond. Thanks to the 1H and two-dimensional NOESY (Nuclear Overhauser Effect Spectroscopy) NMR analyses, we assessed the bonding of the APTMS to the silica surface and determined the best ratio of injected molecules to the surface area of the nanoparticle to obtain complete coverage. Then, we attached gold seeds to the silica surface, and we merged them by adding gold precursor through a slow injection, employing a syringe pump. In this way, we avoided self-nucleation of gold nanoparticles in the chemical environment, achieving uniform gold coverage. As a further development, by exploiting the variable thickness of the silica shell, the gold film could also be employed to build an optical microcavity around the QD (increasing the QD-gold film distance through a thicker silica shell). In general, silica shells around QDs can be used as a template to colloidally grow more sophisticated optical structures able to impart additional effects to tune the emitter properties. Bibliography (1) Carbone, L.; Nobile, C.; De Giorgi, M.; Sala, F. D.; Morello, G.; Pompa, P.; Hytch, M.; Snoeck, E.; Fiore, A.; Franchini, I. R.; Nadasan, M.; Silvestre, A. F.; Chiodo, L.; Kudera, S.; Cingolani, R.; Krahne, R.; Manna, L. Nano Lett. 2007, 7 (10), 2942–2950. (2) Tessier, M. D.; Dupont, D.; De Nolf, K.; De Roo, J.; Hens, Z. Chem. Mater. 2015, 27 (13), 4893–4898. (3) Fiorito, S.; Silvestri, M.; Cirignano, M.; Marini, A.; Di Stasio, F. ACS Appl. Nano Mater. 2024, 7 (4), 3724–3733 (4) Leardi, R. Analytica Chimica Acta 2009, 652 (1), 161–172. (5) Ji, B.; Giovanelli, E.; Habert, B.; Spinicelli, P.; Nasilowski, M.; Xu, X.; Lequeux, N.; Hugonin, J.-P.; Marquier, F.; Greffet, J.-J.; Dubertret, B. Nature Nanotech 2015, 10 (2), 170–175.
Silica shelling of Quantum Dots and gold film development
M. Garbarino;
2025-01-01
Abstract
Colloidal Quantum Dots (QDs) are an established class of optoelectronic materials thanks to their tunable and highly efficient emission. The encapsulation of QDs in silica shells is a well-known procedure to protect them from the external environment and obtain dispersibility in polar solvents. Here, we have coated different types of QDs (CdSe@CdS [1] and InP@ZnS [2]) with silica shells of controlled thickness. The silica shells were obtained exploiting the Reverse Microemulsion reaction combined with an experimental design approach [3,4]. In addition to this, we deposited a uniform gold film over the silica shell. The combination of the QDs emission with the gold plasmon resonance enables an improvement in the optical properties, as already demonstrated [5]. As a first step to achieve this goal, the functionalization of the silica shell for further gold seeds attachment is required. With such aim, we employed (3-Aminopropyl)trimethoxysilane (APTMS), with an amino group binding to the gold seed, helping in the development of the film. Instead, the silicon of the APTMS binds strongly to the silica surface through a covalent bond. Thanks to the 1H and two-dimensional NOESY (Nuclear Overhauser Effect Spectroscopy) NMR analyses, we assessed the bonding of the APTMS to the silica surface and determined the best ratio of injected molecules to the surface area of the nanoparticle to obtain complete coverage. Then, we attached gold seeds to the silica surface, and we merged them by adding gold precursor through a slow injection, employing a syringe pump. In this way, we avoided self-nucleation of gold nanoparticles in the chemical environment, achieving uniform gold coverage. As a further development, by exploiting the variable thickness of the silica shell, the gold film could also be employed to build an optical microcavity around the QD (increasing the QD-gold film distance through a thicker silica shell). In general, silica shells around QDs can be used as a template to colloidally grow more sophisticated optical structures able to impart additional effects to tune the emitter properties. Bibliography (1) Carbone, L.; Nobile, C.; De Giorgi, M.; Sala, F. D.; Morello, G.; Pompa, P.; Hytch, M.; Snoeck, E.; Fiore, A.; Franchini, I. R.; Nadasan, M.; Silvestre, A. F.; Chiodo, L.; Kudera, S.; Cingolani, R.; Krahne, R.; Manna, L. Nano Lett. 2007, 7 (10), 2942–2950. (2) Tessier, M. D.; Dupont, D.; De Nolf, K.; De Roo, J.; Hens, Z. Chem. Mater. 2015, 27 (13), 4893–4898. (3) Fiorito, S.; Silvestri, M.; Cirignano, M.; Marini, A.; Di Stasio, F. ACS Appl. Nano Mater. 2024, 7 (4), 3724–3733 (4) Leardi, R. Analytica Chimica Acta 2009, 652 (1), 161–172. (5) Ji, B.; Giovanelli, E.; Habert, B.; Spinicelli, P.; Nasilowski, M.; Xu, X.; Lequeux, N.; Hugonin, J.-P.; Marquier, F.; Greffet, J.-J.; Dubertret, B. Nature Nanotech 2015, 10 (2), 170–175.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
