Cherie R Kagan Research Group

@article{Guo2021,
title = {Broadband Circular Polarizers via Coupling in 3D Plasmonic Meta-Atom Arrays},
author = {Jiacen Guo and Ji-Young Kim and Shengsong Yang and Jun Xu and Yun Chang Choi and Aaron Stein and Christopher B. Murray and Nicholas A. Kotov and Cherie R. Kagan},
url = {https://pubs.acs.org/doi/abs/10.1021/acsphotonics.1c00310},
doi = {10.1021/acsphotonics.1c00310},
year = {2021},
date = {2021-04-13},
journal = {ACS Photonics},
abstract = {We report broadband circular polarizers achieved by engineering the electromagnetic coupling between 3D meta-atoms in large-area arrays. The 3D meta-atoms are composed of bulk Au/Au nanocrystal (NC) bilayer helical arms, tailored in their number, length, and curvature through a one-step patterning process and postfabrication chemical and thermal treatments. By tuning the meta-atom array periodicity, hybridization originating from dipole–dipole and quadrupole–quadrupole interactions broadens the chiral response. We demonstrate circular polarizers operating at wavelengths spanning 2.5 to 5 μm, with a maximal transmission difference between left- and right-hand circularly polarized light of 43%.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zhao2021,
title = {Enhanced Carrier Transport in Strongly Coupled, Epitaxially Fused CdSe Nanocrystal Solids},
author = {Qinghua Zhao and Guillaume Gouget and Jiacen Guo and Shengsong Yang and Tianshuo Zhao and Daniel B. Straus and Chengyang Qian and Nuri Oh and Han Wang and Christopher B. Murray and Cherie R. Kagan},
url = {https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.1c00860},
doi = {10.1021/acs.nanolett.1c00860},
year = {2021},
date = {2021-04-01},
journal = {Nano Letters},
volume = {21},
number = {7},
pages = {3318–3324},
abstract = {Strongly coupled, epitaxially fused colloidal nanocrystal (NC) solids are promising solution-processable semiconductors to realize optoelectronic devices with high carrier mobilities. Here, we demonstrate sequential, solid-state cation exchange reactions to transform epitaxially connected PbSe NC thin films into Cu2Se nanostructured thin-film intermediates and then successfully to achieve zinc-blende, CdSe NC solids with wide epitaxial necking along {100} facets. Transient photoconductivity measurements probe carrier transport at nanometer length scales and show a photoconductance of 0.28(1) cm2 V–1 s–1, the highest among CdSe NC solids reported. Atomic-layer deposition of a thin Al2O3 layer infiltrates and protects the structure from fusing into a polycrystalline thin film during annealing and further improves the photoconductance to 1.71(5) cm2 V–1 s–1 and the diffusion length to 760 nm. We fabricate field-effect transistors to study carrier transport at micron length scales and realize high electron mobilities of 35(3) cm2 V–1 s–1 with on–off ratios of 106 after doping.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Kagan2020,
title = {Colloidal Quantum Dots as Platforms for Quantum Information Science},
author = {Cherie R. Kagan and Lee C. Bassett and Christopher B. Murray and Sarah M. Thompson},
url = {https://pubs.acs.org/doi/abs/10.1021/acs.chemrev.0c00831},
doi = {10.1021/acs.chemrev.0c00831},
year = {2020},
date = {2020-12-29},
journal = {Chemical Reviews},
volume = {121},
number = {5},
pages = {3186–3233},
abstract = {Colloidal quantum dots (QDs) are nanoscale semiconductor crystals with surface ligands that enable their dispersion in solvents. Quantum confinement effects facilitate wave function engineering to sculpt the spatial distribution of charge and spin states and thus the energy and dynamics of QD optical transitions. Colloidal QDs can be integrated in devices using solution-based assembly methods to position single QDs and to create ordered QD arrays. Here, we describe the synthesis, assembly, and photophysical properties of colloidal QDs that have captured scientific imagination and have been harnessed in optical applications. We focus especially on the current understanding of their quantum coherent effects and opportunities to exploit QDs as platforms for quantum information science. Freedom in QD design to isolate and control the quantum mechanical properties of charge, spin, and light presents various approaches to create systems with robust, addressable quantum states. We consider the attributes of QDs for optically addressable qubits in emerging quantum computation, sensing, simulation, and communication technologies, e.g., as robust sources of indistinguishable, single photons that can be integrated into photonic structures to amplify, direct, and tune their emission or as hosts for isolated, coherent spin states that can be coupled to light or to other spins in QD arrays.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Kagan2020b,
title = {Self-assembly for electronics},
author = {Cherie R. Kagan and Taeghwan Hyeon and Dae-Hyeong Kim and Ricardo Ruiz and Maryann C. Tung and H.-S. Philip Wong },
url = {https://link.springer.com/article/10.1557/mrs.2020.248},
doi = {10.1557/mrs.2020.248},
year = {2020},
date = {2020-12-24},
journal = {MRS Bulletin},
volume = {45},
pages = {807–814},
abstract = {Self-assembly, a process in which molecules, polymers, and particles are driven by local interactions to organize into patterns and functional structures, is being exploited in advancing silicon electronics and in emerging, unconventional electronics. Silicon electronics has relied on lithographic patterning of polymer resists at progressively smaller lengths to scale down device dimensions. Yet, this has become increasingly difficult and costly. Assembly of block copolymers and colloidal nanoparticles allows resolution enhancement and the definition of essential shapes to pattern circuits and memory devices. As we look to a future in which electronics are integrated at large numbers and in new forms for the Internet of Things and wearable and implantable technologies, we also explore a broader material set. Semiconductor nanoparticles and biomolecules are prized for their size-, shape-, and composition-dependent properties and for their solution-based assembly and integration into devices that are enabling unconventional manufacturing and new device functions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}