Yukio Cho

All Publications

• Crystalline 1D Coordination Polymer Inhibitor Layer Leads to Vertical Sidewalls in Selectively Deposited ZnO on Nanoscale Patterns. ACS nano Shearer, A., Cho, Y., Kim, M., Werbrouck, A., Liu, T. L., Takacs, C. J., Shong, B., Bent, S. F. 2025

  Abstract

  Area-selective atomic layer deposition (AS-ALD) is a promising technique for the fabrication of next-generation nanoelectronics. There are two main challenges in AS-ALD: (1) achieving high selectivity of deposition on the growth regions, and (2) preventing mushrooming of the growth material onto the nongrowth regions and achieving well-defined interfaces. In this work, we use benzenethiol (BT) as an inhibitor in the selective deposition of ZnO on SiO2 in the presence of copper with and without a native oxide (Cu/CuOx). We observe that BT forms a monolayer on the Cu surface and a Cu-thiolate multilayer structure on CuOx. Using grazing incidence X-ray diffraction combined with simulations, we find that the multilayer structure is crystalline and composed of 1D coordination polymers of Cu-thiolate. Using ellipsometry and X-ray photoelectron spectroscopy, we show that the BT consumes the entirety of the CuOx during multilayer formation, allowing the multilayer thickness to be tuned by the thickness of the original oxide. Both the monolayer BT and the multilayer BT prove to be effective inhibitors of ZnO ALD, blocking nearly 500 ALD cycles, which is more than twice that achieved with other thiol inhibitors. Finally, we demonstrate that the multilayer structure can prevent mushrooming of the ALD material onto the nongrowth surface of nanoscale patterns, creating vertical sidewalls with well-defined material interfaces and providing excellent pattern transfer, even for a relatively thick deposited film. As such, these results demonstrate that BT is not only an effective inhibitor but also that its ability to form tunable multilayers makes it well-suited for highly precise nanopatterning applications.

  View details for DOI 10.1021/acsnano.4c16115

  View details for PubMedID 40116589

• Atomic and molecular layer deposition on unconventional substrates: challenges and perspectives from energy applications. Nanotechnology Cho, Y., D'Acunto, G., Nanda, J., Bent, S. F. 2025

  Abstract

  The use of atomic layer deposition (ALD) and molecular layer deposition (MLD) in energy sectors such as catalysis, batteries, and membranes has emerged as a growing approach to fine-tune surface and interfacial properties at the nanoscale, thereby enhancing performance. However, compared to the microelectronics field where ALD is well established on conventional substrates such as silicon wafers, employing ALD and MLD in energy applications often requires depositing films on unconventional substrates such as nanoparticles, secondary particles, composite electrodes, membranes with wide pore size distribution, and two-dimensional materials. This review examines the challenges and perspectives associated with implementing ALD and MLD on these unconventional substrates. We discuss how the complex surface chemistries and intricate morphologies of these substrates can lead to non-ideal growth behaviors, resulting in inconsistent film properties compared to those grown on standard wafers, even within the same deposition process. Additionally, the review outlines the strengths and limitations of several characterization techniques when employed for ALD or MLD films grown on unconventional substrates, and it highlights a few exemplary studies in which these growth methods have been applied for energy applications with a focus on energy storage. With ALD and MLD gaining increasing attention, this review aims to deepen the understanding of how to achieve controllable, predictable, and scalable deposition with atomic-scale precision, ultimately advancing the development of more efficient and durable energy devices.

  View details for DOI 10.1088/1361-6528/adbd49

  View details for PubMedID 40048750

• Effects of catholyte aging on high-nickel NMC cathodes in sulfide all-solid-state batteries. Materials horizons Li, Y., Cho, Y., Cai, J., Kim, C., Zheng, X., Wu, W., Musgrove, A. L., Su, Y., Sacci, R. L., Chen, Z., Nanda, J., Yang, G. 2024

  Abstract

  Sulfide solid-state electrolytes (SSEs) in all-solid-state batteries (SSBs) are recognized for their high ionic conductivity and inherent safety. The LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode offers a high thermodynamic potential of approximately 3.8 V vs. Li/Li+ and a theoretical specific capacity of 200 mA h g-1. However, the practical utilization of NMC811 in sulfide SSBs faces significant interfacial challenges. The oxidation instability of sulfide solid electrolytes against NMC811 and the formation of the cathode electrolyte interphase (CEI) during cycling lead to degradation and reduced cell performance. Volumetric changes in NMC during lithiation and de-lithiation can also cause detachment from sulfide electrolytes or internal particle cracking. Despite extensive galvanostatic cycling studies to address the issues, the calendar life of sulfide SSBs remains poorly understood. Here, we systematically studied the effects of four different catholytes on the calendar aging of LiNbO3 (LNO)-coated NMC811, including Li6PS5Cl (LPSCl), Li3InCl6-Li6PS5Cl (LIC-LPSCl), Li3YCl6-Li6PS5Cl (LYC-LPSCl), and Li10GeP2S12 (LGPS). Our results indicate that LPSCl provides optimal capacity retention when stored at high state-of-charge (SOC) at room temperature, but the LIC-LPSCl cathode shows significant capacity degradation and chemical incompatibility. We also established an effective electrochemical calendar aging testing protocol to simulate daily usage, enabling quick inference of the calendar life of SSBs. This new testing approach accelerates materials selection strategies for high-nickel NMC composite cathodes in sulfide SSBs.

  View details for DOI 10.1039/d4mh01211a

  View details for PubMedID 39508797

• Interfacial dynamics mediate surface binding events on supramolecular nanostructures. Nature communications Christoff-Tempesta, T., Cho, Y., Kaser, S. J., Uliassi, L. D., Zuo, X., Hilburg, S. L., Pozzo, L. D., Ortony, J. H. 2024; 15 (1): 7749

  Abstract

  The dynamic behavior of biological materials is central to their functionality, suggesting that interfacial dynamics could also mediate the activity of chemical events at the surfaces of synthetic materials. Here, we investigate the influence of surface flexibility and hydration on heavy metal remediation by nanostructures self-assembled from small molecules that are decorated with surface-bound chelators in water. We find that incorporating short oligo(ethylene glycol) spacers between the surface and interior domain of self-assembled nanostructures can drastically increase the conformational mobility of surface-bound lead-chelating moieties and promote interaction with surrounding water. In turn, we find the binding affinities of chelators tethered to the most flexible surfaces are more than ten times greater than the least flexible surfaces. Accordingly, nanostructures composed of amphiphiles that give rise to the most dynamic surfaces are capable of remediating thousands of liters of 50 ppb Pb2+-contaminated water with single grams of material. These findings establish interfacial dynamics as a critical design parameter for functional self-assembled nanostructures.

  View details for DOI 10.1038/s41467-024-51494-4

  View details for PubMedID 39237531

  View details for PubMedCentralID 3374587

• Geometric Transformations Afforded by Rotational Freedom in Aramid Amphiphile Nanostructures. Journal of the American Chemical Society Cho, Y., Choi, Y., Kaser, S. J., Meacham, R., Christoff-Tempesta, T., Wu, S., Zuo, X., Ortony, J. H. 2023; 145 (42): 22954-22963

  Abstract

  Molecular self-assembly in water leads to nanostructure geometries that can be tuned owing to the highly dynamic nature of amphiphiles. There is growing interest in strongly interacting amphiphiles with suppressed dynamics, as they exhibit ultrastability in extreme environments. However, such amphiphiles tend to assume a limited range of geometries upon self-assembly due to the specific spatial packing induced by their strong intermolecular interactions. To overcome this limitation while maintaining structural robustness, we incorporate rotational freedom into the aramid amphiphile molecular design by introducing a diacetylene moiety between two aramid units, resulting in diacetylene aramid amphiphiles (D-AAs). This design strategy enables rotations along the carbon-carbon sp hybridized bonds of an otherwise fixed aramid domain. We show that varying concentrations and equilibration temperatures of D-AA in water lead to self-assembly into four different nanoribbon geometries: short, extended, helical, and twisted nanoribbons, all while maintaining robust structure with thermodynamic stability. We use advanced microscopy, X-ray scattering, spectroscopic techniques, and two-dimensional (2D) NMR to understand the relationship between conformational freedom within strongly interacting amphiphiles and their self-assembly pathways.

  View details for DOI 10.1021/jacs.3c04598

  View details for PubMedID 37819710