Cherie R Kagan Research Group
The Kagan group’s research is focused on studying the chemical and physical properties of nanostructured materials and in integrating materials with optical, electrical, magnetic, mechanical, and thermal properties for (multi-)functional devices. We combine the flexibility of chemistry and bottom-up assembly with top-down fabrication techniques to design materials and devices. We explore the properties of materials and measure the characteristics of devices using spatially- and temporally-resolved optical spectroscopies, AC and DC electrical techniques, electrochemistry, scanning probe and electron microscopies, and analytical measurements.
Announcements
- Congratulations, Chavez!
Chavez Lawrence was named a National GEM Conference Finalist.
- Congratulations, Daniel!
Daniel Straus has won a Blavatnik Award for Young Scientists. video
- Welcome, Akhila!
Akhila Mallavarapu has joined our group as a postdoctoral researcher.
- Congratulations, Jun!
Jun has won the the SEAS Masters Award for Research and joined our group as a first-year PhD student in the Electrical and Systems Engineering Department.
- Congratulations, Qinghua!
Congratulations to Qinghua on defending her PhD thesis!
- Congratulations, Han!
Congratulations to Han on defending his PhD thesis!
Research Highlights
Shulevitz, Henry J.; Huang, Tzu-Yung; Xu, Jun; Neuhaus, Steven; Patel, Raj N.; Lee C. Bassett, Cherie R. Kagan
Template-Assisted Self Assembly of Fluorescent Nanodiamonds for Scalable Quantum Technologies Journal Article Forthcoming
In: Forthcoming.
@article{Shulevitz2021,
title = {Template-Assisted Self Assembly of Fluorescent Nanodiamonds for Scalable Quantum Technologies},
author = {Henry J. Shulevitz and Tzu-Yung Huang and Jun Xu and Steven Neuhaus and Raj N. Patel and Lee C. Bassett, Cherie R. Kagan},
url = {https://arxiv.org/abs/2111.14921},
year = {2021},
date = {2021-12-01},
urldate = {2021-12-01},
abstract = {Milled nanodiamonds containing nitrogen-vacancy (NV) centers provide an excellent platform for sensing applications as they are optically robust, have nanoscale quantum sensitivity, and form colloidal dispersions which enable bottom-up assembly techniques for device integration. However, variations in their size, shape, and surface chemistry limit the ability to position individual nanodiamonds and statistically study properties that affect their optical and quantum characteristics. Here, we present a scalable strategy to form ordered arrays of nanodiamonds using capillary-driven, template-assisted self assembly. This method enables the precise spatial arrangement of isolated nanodiamonds with diameters below 50 nm across millimeter-scale areas. Measurements of over 200 assembled nanodiamonds yield a statistical understanding of their structural, optical, and quantum properties. The NV centers' spin and charge properties are uncorrelated with nanodiamond size, but rather are consistent with heterogeneity in their nanoscale environment. This flexible assembly method, together with improved understanding of the material, will enable the integration of nanodiamonds into future quantum photonic and electronic devices.},
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}
Milled nanodiamonds containing nitrogen-vacancy (NV) centers provide an excellent platform for sensing applications as they are optically robust, have nanoscale quantum sensitivity, and form colloidal dispersions which enable bottom-up assembly techniques for device integration. However, variations in their size, shape, and surface chemistry limit the ability to position individual nanodiamonds and statistically study properties that affect their optical and quantum characteristics. Here, we present a scalable strategy to form ordered arrays of nanodiamonds using capillary-driven, template-assisted self assembly. This method enables the precise spatial arrangement of isolated nanodiamonds with diameters below 50 nm across millimeter-scale areas. Measurements of over 200 assembled nanodiamonds yield a statistical understanding of their structural, optical, and quantum properties. The NV centers' spin and charge properties are uncorrelated with nanodiamond size, but rather are consistent with heterogeneity in their nanoscale environment. This flexible assembly method, together with improved understanding of the material, will enable the integration of nanodiamonds into future quantum photonic and electronic devices.
Ahn, Junhyuk; Jeon, Sanghyun; Woo, Ho Kun; Bang, Junsung; Lee, Yong Min; Neuhaus, Steven J.; Lee, Woo Seok; Park, Taesung; Lee, Sang Yeop; Jung, Byung Ku; Joh, Hyungmok; Seong, Mingi; Choi, Ji-hyuk; Yoon, Ho Gyu; Kagan, Cherie R.; Oh, Soong Ju
Ink-Lithography for Property Engineering and Patterning of Nanocrystal Thin Films Journal Article
In: ACS Nano, 2021.
@article{Ahn2021,
title = {Ink-Lithography for Property Engineering and Patterning of Nanocrystal Thin Films},
author = {Junhyuk Ahn and Sanghyun Jeon and Ho Kun Woo and Junsung Bang and Yong Min Lee and Steven J. Neuhaus and Woo Seok Lee and Taesung Park and Sang Yeop Lee and Byung Ku Jung and Hyungmok Joh and Mingi Seong and Ji-hyuk Choi and Ho Gyu Yoon and Cherie R. Kagan and Soong Ju Oh},
url = {https://pubs.acs.org/doi/abs/10.1021/acsnano.1c04772},
doi = {10.1021/acsnano.1c04772},
year = {2021},
date = {2021-09-08},
urldate = {2021-09-08},
journal = {ACS Nano},
abstract = {Next-generation devices and systems require the development and integration of advanced materials, the realization of which inevitably requires two separate processes: property engineering and patterning. Here, we report a one-step, ink-lithography technique to pattern and engineer the properties of thin films of colloidal nanocrystals that exploits their chemically addressable surface. Colloidal nanocrystals are deposited by solution-based methods to form thin films and a local chemical treatment is applied using an ink-printing technique to simultaneously modify (i) the chemical nature of the nanocrystal surface to allow thin-film patterning and (ii) the physical electronic, optical, thermal, and mechanical properties of the nanocrystal thin films. The ink-lithography technique is applied to the library of colloidal nanocrystals to engineer thin films of metals, semiconductors, and insulators on both rigid and flexible substrates and demonstrate their application in high-resolution image replications, anticounterfeit devices, multicolor filters, thin-film transistors and circuits, photoconductors, and wearable multisensors.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Next-generation devices and systems require the development and integration of advanced materials, the realization of which inevitably requires two separate processes: property engineering and patterning. Here, we report a one-step, ink-lithography technique to pattern and engineer the properties of thin films of colloidal nanocrystals that exploits their chemically addressable surface. Colloidal nanocrystals are deposited by solution-based methods to form thin films and a local chemical treatment is applied using an ink-printing technique to simultaneously modify (i) the chemical nature of the nanocrystal surface to allow thin-film patterning and (ii) the physical electronic, optical, thermal, and mechanical properties of the nanocrystal thin films. The ink-lithography technique is applied to the library of colloidal nanocrystals to engineer thin films of metals, semiconductors, and insulators on both rigid and flexible substrates and demonstrate their application in high-resolution image replications, anticounterfeit devices, multicolor filters, thin-film transistors and circuits, photoconductors, and wearable multisensors.
Straus, Daniel B.; Kagan, Cherie R.
Photophysics of Two-Dimensional Semiconducting Organic-Inorganic Metal-Halide Perovskites Journal Article Forthcoming
In: Forthcoming.
@article{Straus2021,
title = {Photophysics of Two-Dimensional Semiconducting Organic-Inorganic Metal-Halide Perovskites},
author = {Daniel B. Straus and Cherie R. Kagan},
url = {10.1146/annurev-physchem-082820-015402},
doi = {https://arxiv.org/abs/2108.13501},
year = {2021},
date = {2021-08-30},
urldate = {2021-08-30},
abstract = {2D organic-inorganic hybrid perovskites (2DHPs) consist of alternating anionic metal-halide and cationic organic layers. They have widely tunable structural and optical properties. We review the role of the organic cation in defining the structural and optical properties of 2DHPs through example lead iodide 2DHPs. Even though excitons reside in the metal halide layers, the organic and inorganic frameworks cannot be separated-they must be considered as a single unit to fully understand the photophysics of 2DHPs. We correlate cation-induced distortion and disorder in the inorganic lattice with the resulting optical properties. We also discuss the role of the cation in creating and altering the discrete excitonic structure that appears at cryogenic temperatures in some 2DHPs, including the cation-dependent presence of hot exciton photoluminescence. We conclude our review with an outlook for 2DHPs, highlighting existing gaps in fundamental knowledge as well as potential future applications.},
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}
2D organic-inorganic hybrid perovskites (2DHPs) consist of alternating anionic metal-halide and cationic organic layers. They have widely tunable structural and optical properties. We review the role of the organic cation in defining the structural and optical properties of 2DHPs through example lead iodide 2DHPs. Even though excitons reside in the metal halide layers, the organic and inorganic frameworks cannot be separated-they must be considered as a single unit to fully understand the photophysics of 2DHPs. We correlate cation-induced distortion and disorder in the inorganic lattice with the resulting optical properties. We also discuss the role of the cation in creating and altering the discrete excitonic structure that appears at cryogenic temperatures in some 2DHPs, including the cation-dependent presence of hot exciton photoluminescence. We conclude our review with an outlook for 2DHPs, highlighting existing gaps in fundamental knowledge as well as potential future applications.
Maguire, Shawn M.; Boyle, Michael J.; Bilchak, Connor R.; Demaree, John Derek; Keller, Austin W.; Krook, Nadia M.; Ohno, Kohji; Kagan, Cherie R.; Murray, Christopher B.; Rannou, Patrice; Composto, Russell J.
Grafted Nanoparticle Surface Wetting during Phase Separation in Polymer Nanocomposite Films Journal Article
In: ACS Applied Materials & Interfaces, 13 (31), pp. 37628–37637, 2021.
@article{Maguire2021,
title = {Grafted Nanoparticle Surface Wetting during Phase Separation in Polymer Nanocomposite Films},
author = {Shawn M. Maguire and Michael J. Boyle and Connor R. Bilchak and John Derek Demaree and Austin W. Keller and Nadia M. Krook and Kohji Ohno and Cherie R. Kagan and Christopher B. Murray and Patrice Rannou and Russell J. Composto},
url = {https://pubs.acs.org/doi/abs/10.1021/acsami.1c09233},
doi = {10.1021/acsami.1c09233},
year = {2021},
date = {2021-07-29},
journal = {ACS Applied Materials & Interfaces},
volume = {13},
number = {31},
pages = {37628–37637},
abstract = {Wetting of polymer-grafted nanoparticles (NPs) in a polymer nanocomposite (PNC) film is driven by a difference in surface energy between components as well as bulk thermodynamics, namely, the value of the interaction parameter, χ. The interplay between these contributions is investigated in a PNC containing 25 wt % polymethyl methacrylate (PMMA)-grafted silica NPs (PMMA-NPs) in poly(styrene-ran-acrylonitrile) (SAN) upon annealing above the lower critical solution temperature (LCST, 160 °C). Atomic force microscopy (AFM) studies show that the areal density of particles increases rapidly and then approaches 80% of that expected for random close-packed hard spheres. A slightly greater areal density is observed at 190 °C compared to 170 °C. The PMMA-NPs are also shown to prevent dewetting of PNC films under conditions where the analogous polymer blend is unstable. Transmission electron microscopy (TEM) imaging shows that PMMA-NPs symmetrically wet both interfaces and form columns that span the free surface and substrate interface. Using grazing-incidence Rutherford backscattering spectrometry (GI-RBS), the PMMA-NP surface excess (Z*) initially increases rapidly with time and then approaches a constant value at longer times. Consistent with the areal density, Z* is slightly greater at deeper quench depths, which is attributed to the more unfavorable interactions between the PMMA brush and SAN segments. The Z* values at early times are used to determine the PMMA-NP diffusion coefficients, which are significantly larger than theoretical predictions. These studies provide insights into the interplay between wetting and phase separation in PNCs and can be utilized in nanotechnology applications where surface-dependent properties, such as wettability, durability, and friction, are important.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Wetting of polymer-grafted nanoparticles (NPs) in a polymer nanocomposite (PNC) film is driven by a difference in surface energy between components as well as bulk thermodynamics, namely, the value of the interaction parameter, χ. The interplay between these contributions is investigated in a PNC containing 25 wt % polymethyl methacrylate (PMMA)-grafted silica NPs (PMMA-NPs) in poly(styrene-ran-acrylonitrile) (SAN) upon annealing above the lower critical solution temperature (LCST, 160 °C). Atomic force microscopy (AFM) studies show that the areal density of particles increases rapidly and then approaches 80% of that expected for random close-packed hard spheres. A slightly greater areal density is observed at 190 °C compared to 170 °C. The PMMA-NPs are also shown to prevent dewetting of PNC films under conditions where the analogous polymer blend is unstable. Transmission electron microscopy (TEM) imaging shows that PMMA-NPs symmetrically wet both interfaces and form columns that span the free surface and substrate interface. Using grazing-incidence Rutherford backscattering spectrometry (GI-RBS), the PMMA-NP surface excess (Z*) initially increases rapidly with time and then approaches a constant value at longer times. Consistent with the areal density, Z* is slightly greater at deeper quench depths, which is attributed to the more unfavorable interactions between the PMMA brush and SAN segments. The Z* values at early times are used to determine the PMMA-NP diffusion coefficients, which are significantly larger than theoretical predictions. These studies provide insights into the interplay between wetting and phase separation in PNCs and can be utilized in nanotechnology applications where surface-dependent properties, such as wettability, durability, and friction, are important.
Yoon, Bo Kyeong; Tae, Hyunhyuk; Jackman, Joshua A.; Guha, Supratik; Kagan, Cherie R.; Margenot, Andrew J.; Rowland, Diane L.; Weiss, Paul S.; Cho, Nam-Joon
Entrepreneurial Talent Building for 21st Century Agricultural Innovation Journal Article
In: ACS Nano, 15 (7), pp. 10748–10758, 2021.
@article{Yoon2021,
title = {Entrepreneurial Talent Building for 21st Century Agricultural Innovation},
author = {Bo Kyeong Yoon and Hyunhyuk Tae and Joshua A. Jackman and Supratik Guha and Cherie R. Kagan and Andrew J. Margenot and Diane L. Rowland and Paul S. Weiss and Nam-Joon Cho},
url = {https://pubs.acs.org/doi/abs/10.1021/acsnano.1c05980},
doi = {10.1021/acsnano.1c05980},
year = {2021},
date = {2021-07-16},
urldate = {2021-07-16},
journal = {ACS Nano},
volume = {15},
number = {7},
pages = {10748–10758},
abstract = {Agricultural innovation is a key component of the global economy and enhances food security, health, and nutrition. Current innovation efforts focus mainly on supporting the transition to sustainable food systems, which is expected to harness technological advances across a range of fields. In this Nano Focus, we discuss how such efforts would benefit from not only supporting farmer participation in deciding transition pathways but also in fostering the interdisciplinary training and development of entrepreneurial-minded farmers, whom we term “AgTech Pioneers”, to participate in cross-sector agricultural innovation ecosystems as cocreators and informed users of developing and future technologies. Toward this goal, we discuss possible strategies based on talent development, cross-disciplinary educational and training programs, and innovation clusters to build an AgTech Pioneer ecosystem, which can help to reinvigorate interest in farming careers and to identify and address challenges and opportunities in agriculture by accelerating and applying advances in nanoscience, nanotechnology, and related fields.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Agricultural innovation is a key component of the global economy and enhances food security, health, and nutrition. Current innovation efforts focus mainly on supporting the transition to sustainable food systems, which is expected to harness technological advances across a range of fields. In this Nano Focus, we discuss how such efforts would benefit from not only supporting farmer participation in deciding transition pathways but also in fostering the interdisciplinary training and development of entrepreneurial-minded farmers, whom we term “AgTech Pioneers”, to participate in cross-sector agricultural innovation ecosystems as cocreators and informed users of developing and future technologies. Toward this goal, we discuss possible strategies based on talent development, cross-disciplinary educational and training programs, and innovation clusters to build an AgTech Pioneer ecosystem, which can help to reinvigorate interest in farming careers and to identify and address challenges and opportunities in agriculture by accelerating and applying advances in nanoscience, nanotechnology, and related fields.