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1. Systematic control of the rate of singlet fission within 6,13-diphenylpentacene aggregates with PbS quantum dot templates

   https://doi.org/10.1039/C8FD00157J  

   Wang, Chen; Kodaimati, Mohamad S.; Lian, Shichen; Weiss, Emily A. (July 2019, Faraday Discussions)

   Lead chalcogenide quantum dots (QDs) are promising acceptors for photovoltaic devices that harness the singlet fission (SF) mechanism. The rate of singlet fission of polyacenes in the presence of QDs is a critical parameter in determining the performance of such devices. The present study demonstrates that the rates of SF in a pentacene derivative, 6,13-diphenylanthracene (DPP), are modulated by forming coaggregates with PbS QDs in aqueous dispersions. PbS QDs generally accelerate SF within DPP aggregates, and the extent of acceleration depends on the size of the QD. The average rate of SF increases from 0.074 ps −1 for DPP-only aggregates to 0.37 ps −1 within DPP-D co-aggregates for QDs with radius 2.2 nm, whereas co-aggregation with the smallest ( r = 1.6 nm) and largest ( r = 2.7 nm) QDs we tried only slightly change the SF rate. The rate variation is associated with (i) the density of surface ligands, which is influenced by the faceting of the PbS surface, and (ii) the local dielectric constant for DPP. To accelerate SF, the ligands should be dense enough to provide sufficient affinity for DPP aggregates and effectively perturb the perpendicular alignment of DPP monomers within aggregates to increase the intermolecular coupling that promotes SF, but should not be too dense so as to form a low dielectric environment that disfavors SF. The study suggests that it is critical to consider the influence of the microenvironment of the QD surface on photophysical processes when fabricating QD/organic hybrid devices. 

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2. Purcell-Induced Bright Single Photon Emitters in Hexagonal Boron Nitride

   https://doi.org/10.1021/acs.nanolett.4c02581  

   Sakib, Mashnoon Alam; Triplett, Brandon; Harris, William; Hussain, Naveed; Senichev, Alexander; Momenzadeh, Melika; Bocanegra, Joshua; Vabishchevich, Polina; Wu, Ruqian; Boltasseva, Alexandra; et al (October 2024, Nano Letters)

   Single photon emitters (SPEs) in hexagonal boron nitride (hBN) are elementary building blocks for room-temperature on-chip quantum photonic technologies. However, fundamental challenges, such as slow radiative decay and nondeterministic placement of the emitters, limit their full potential. Here, we demonstrate large-area arrays of plasmonic nanoresonators (PNRs) for Purcell-induced room-temperature SPEs by engineering emitter-cavity coupling and enhancing radiative emission. Gold-coated silicon pillars with an alumina spacer enable a 10-fold local-field enhancement in the emission band of native hBN defects. We observe bright SPEs with an average saturated emission rate surpassing 5 million counts per second, an average lifetime of <0.5 ns, and 29% yield. Density functional theory reveals the beneficial role of an alumina spacer between hBN and gold, mitigating the electronic broadening of emission from defects proximal to the metal. Our results offer arrays of bright, heterogeneously integrated single-photon sources, paving the way for robust and scalable quantum information systems. 

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3. Dual-Modal Nanoplasmonic Light Upconversion in Broadband Multiresonant Plasmonic Metasurfaces

   https://doi.org/10.1364/CLEO_FS.2024.FTh1P.7  

   Tali, Seied_Ali Safiabadi; Zhou, Wei (January 2024, Optica Publishing Group)

   This study investigates dual-modal plasmon-enhanced light upconversion, combining anti-Stokes photoluminescence (ASPL) and second-harmonic generation (SHG) in Ag/SiO₂/Ag nanolaminate plasmonic crystal metasurfaces. It highlights the distinct emission behaviors of ASPL and SHG in multiresonant plasmonic nanocavities. 

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4. Polarized Superradiance from CsPbBr ₃ Quantum Dot Superlattice with Controlled Interdot Electronic Coupling

   https://doi.org/10.1021/acs.nanolett.5c00478  

   Luo, Lanyin; Tang, Xueting; Park, Junhee; Wang, Chih-Wei; Park, Mansoo; Khurana, Mohit; Singh, Ashutosh; Cheon, Jinwoo; Belyanin, Alexey; Sokolov, Alexei V; et al (April 2025, Nano Letters)

   Cooperative emission of photons from an ensemble of quantum dots (QDs) as superradiance can arise from the electronically coupled QDs with a coherent emitting excited state. This contrasts with superfluorescence (Dicke superradiance), where the cooperative photon emission requires a buildup of coherence in an ensemble of incoherently excited QDs via their coupling to a common radiation mode. In perovskite QDs, superradiance has been rarely observed, unlike superfluorescence, due to the challenge in QD electronic coupling. Here, we report superradiance with a very narrow linewidth (<5 meV) and a large redshift (∼200 meV) from the strongly coupled CsPbBr3 QD superlattice achieved through the combination of quantum confinement and ligand engineering. The superradiance is polarized in contrast to the uncoupled exciton emission from the same superlattice, indicating anisotropic electronic coupling in superlattices. This finding suggests the potential of a perovskite QD superlattice with structurally controllable interdot coupling as the polarized cooperative photon emitters 

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5. Nanoscale 3D spatial addressing and valence control of quantum dots using wireframe DNA origami

   https://doi.org/10.1038/s41467-022-32662-w  

   Chen, Chi; Wei, Xingfei; Parsons, Molly F.; Guo, Jiajia; Banal, James L.; Zhao, Yinong; Scott, Madelyn N.; Schlau-Cohen, Gabriela S.; Hernandez, Rigoberto; Bathe, Mark (December 2022, Nature Communications)

   Abstract Control over the copy number and nanoscale positioning of quantum dots (QDs) is critical to their application to functional nanomaterials design. However, the multiple non-specific binding sites intrinsic to the surface of QDs have prevented their fabrication into multi-QD assemblies with programmed spatial positions. To overcome this challenge, we developed a general synthetic framework to selectively attach spatially addressable QDs on 3D wireframe DNA origami scaffolds using interfacial control of the QD surface. Using optical spectroscopy and molecular dynamics simulation, we investigated the fabrication of monovalent QDs of different sizes using chimeric single-stranded DNA to control QD surface chemistry. By understanding the relationship between chimeric single-stranded DNA length and QD size, we integrated single QDs into wireframe DNA origami objects and visualized the resulting QD-DNA assemblies using electron microscopy. Using these advances, we demonstrated the ability to program arbitrary 3D spatial relationships between QDs and dyes on DNA origami objects by fabricating energy-transfer circuits and colloidal molecules. Our design and fabrication approach enables the geometric control and spatial addressing of QDs together with the integration of other materials including dyes to fabricate hybrid materials for functional nanoscale photonic devices. 

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