Materials Horizons Emerging Investigator Series: Dr Eunho Lee, Seoul National University of Science and Technology, Korea (the Republic of)
Abstract
Our Emerging Investigator Series features exceptional work by early-career researchers working in the field of materials science.
Dr Eunho Lee (ORCID: https://orcid.org/0000-0002-8564-6999 ) received his PhD in Chemical Engineering from Pohang University of Science and Technology (POSTECH) in 2018. He then pursued postdoctoral research at the Rowland Institute at Harvard University and the University of North Texas, focusing on the synthesis of next-generation semiconductors for bioelectronics and neuromorphic applications. In 2021, he began his independent academic career as an Assistant Professor at Kumoh National Institute of Technology, where he established his research direction in organic semiconductor-based neuromorphic device platforms. In 2024, he joined the Department of Chemical and Biomolecular Engineering at Seoul National University of Science and Technology, where he currently leads the Functional Semiconductors and Devices Lab (FSDL).
His group focuses on the molecular design and synthesis of ion-interactive conjugated polymers and their implementation in organic electrochemical transistors (OECTs). His recent studies demonstrate how structural engineering—particularly the incorporation of glycol side chains—can modulate ion uptake dynamics and synaptic behavior, enabling a shift from non-faradaic to faradaic operation regimes. These insights offer promising strategies for enhancing retention and overall performance in neuromorphic electronics. His group’s vision is to bridge fundamental polymer science with practical applications in artificial synapses and bio-inspired electronic systems. His research is currently supported by early-career investigator grants from the National Research Foundation of Korea. He actively promotes interdisciplinary collaboration at the intersection of polymer chemistry, device physics, and computational neuroscience.
Read Eunho Lee's Emerging Investigator Series article ‘Improving ion uptake in artificial synapses through facilitated diffusion mechanisms’ ( https://doi.org/10.1039/D5MH00005J ) and read more about him in the interview below:
MH: Your recent Materials Horizons Communication demonstrates that, in the presence of glycol chains, the doping mechanism in artificial synapses changes to diffusion-dominated which enhances synaptic performance. How has your research evolved from your first article to this most recent article and where do you see your research going in future?
EL: Our initial approach to enhancing synaptic performance in artificial synapses was to tailor the side-chain length of conjugated polymers (CPs). Based on the well-established understanding that ions tend to adsorb onto polymer chains in electrolyte-gated organic transistors (EGOTs), we investigated how chain length modulates ion–polymer interactions and subsequently affects synaptic behavior.1 While conducting this study and reviewing related literature, we recognized that, in addition to strong ion adsorption, efficient and sustained ion injection into the polymer bulk is equally critical to achieve reliable, nonvolatile synaptic behavior. This insight prompted us to explore strategies for promoting ion uptake and transport within the polymer matrix. Rather than directly modifying the polymer backbone at first, we introduced glycol functionality through a crosslinked network formed by azide-based crosslinkers.2 This network facilitated enhanced ion diffusion, shifting the dominant mechanism from surface-limited adsorption to bulk-mediated transport.
Building on this work, we posed the question: could such diffusion-facilitating effects be realized in a single-component polymer system, without relying on external additives or crosslinkers? Our most recent study, “Improving ion uptake in artificial synapses through facilitated diffusion mechanisms”, addresses this question. By incorporating glycol side chains directly into the CPs, we observed a transition from non-faradaic to faradaic ionic processes, as evidenced by electrochemical characterization. This structural modification significantly enhanced ion uptake and enabled stable, highly nonvolatile synaptic responses. Looking forward, our group is working to develop molecular designs that integrate the benefits of glycol functionality into universal CP frameworks. We are particularly focused on designing single-component polymers or dopant-free additive systems that can inherently facilitate ion diffusion through rational tuning of ion–polymer interactions.
MH: What aspect of your work are you most excited about at the moment?
EL: What excites me most at the moment is the ability to rationally design organic semiconductors systems that enable precise control over ion–polymer interactions, particularly in the context of artificial synapses. By tuning these interactions, we can fundamentally alter the doping and de-doping mechanisms in organic mixed conductors, which has a direct impact on synaptic plasticity and long-term memory retention in neuromorphic devices. I am especially interested in exploring how single-component polymer systems—with intrinsically engineered side chains such as glycol groups—can facilitate ion diffusion without relying on external additives or complex device architectures. This approach not only simplifies device fabrication but also enhances operational stability, which is critical for real-world applications. Ultimately, my goal is to bridge the gap between material design and device-level function by developing energy-efficient, highly reliable artificial synapses that can be integrated into future neuromorphic computing platforms. The convergence of polymer chemistry, electrochemical physics, and device engineering in this field offers endless possibilities, and I find that deeply motivating.
MH: In your opinion, what are the most important questions to be asked/answered in this field of research?
EL: In my opinion, one of the most important questions in this field is how to understand and control the fundamental interactions between ions and CPs at the molecular level. While many studies have demonstrated impressive device performance, the microscopic mechanisms that govern ion transport, uptake, and coupling with redox-active polymer backbones remain only partially understood. Developing a more quantitative and predictive framework for ion–polymer interactions is essential to enabling reliable and tunable synaptic behaviors in organic neuromorphic systems. Equally important is the question of how we can translate these fundamental insights into practical and scalable device technologies. In our work, we use organic electrochemical transistors (OECTs) not only as a characterization platform, but also as a testbed for integrating new materials into functional neuromorphic devices. However, moving from laboratory-scale demonstrations to real-world applications requires solving multiple challenges—such as long-term stability, fabrication compatibility, and energy efficiency. Ultimately, I hope to collaborate with researchers across disciplines to bridge this gap, and to contribute to the realization of next-generation neuromorphic semiconductors that are both scientifically elegant and technologically viable.
MH: What do you find most challenging about your research?
EL: One of the most challenging aspects of my research is its highly interdisciplinary nature. Designing and implementing neuromorphic devices requires expertise not only in polymer chemistry and materials science but also in areas such as electrochemistry, device physics, and increasingly, computer engineering. In particular, as neuromorphic systems aim to emulate brain-like computation, understanding how materials-level behavior translates to system-level function often requires knowledge of coding, neural network algorithms, and signal processing. This means that beyond developing materials that exhibit desirable synaptic properties, we must also consider how those behaviors interact with computational models—often requiring simulation, hardware–software interfacing, and algorithmic analysis. For someone with a primarily chemical or materials background, acquiring and integrating such knowledge can be both intellectually stimulating and technically demanding. Bridging these diverse fields demands strong interdisciplinary collaboration, but establishing effective communication across domains—each with its own technical language and priorities—remains a significant challenge. Despite these difficulties, I believe this complexity is where the most impactful innovation happens. The convergence of materials science and computing holds enormous potential for creating energy-efficient, hardware-based artificial intelligence, and I am committed to navigating this complexity to contribute meaningfully to the field.
MH: In which upcoming conferences or events may our readers meet you?
EL: As an early-career researcher, I primarily attend domestic conferences in Korea, including the Korean Institute of Chemical Engineers (KIChE), the Polymer Society of Korea (PSK), and the Korean Carbon Society. I regularly participate in their annual spring and fall meetings, where I present our group's latest work and engage with the broader research community. While funding constraints have limited my ability to frequently attend international conferences, I make a concerted effort to participate in key global meetings whenever possible. In particular, I attend the Materials Research Society (MRS) meetings in the United States, which are among the largest and most influential gatherings in the materials science community. I find these events to be an excellent opportunity to stay connected with the latest developments and to initiate collaborations beyond borders. If you happen to see me at a conference—whether in Korea or abroad—I would be more than happy to have an open and engaging discussion about research. I welcome spontaneous conversations at any time and place, and I look forward to exchanging ideas with fellow scientists who share a passion for materials innovation.
MH: How do you spend your spare time?
EL: Most of my spare time is devoted to my family. I am fortunate to have a wonderful wife and an energetic four-year-old son who bring great joy and stability to my life. We enjoy traveling together, exploring beautiful landscapes, and discovering new culinary experiences. These moments allow me to recharge and maintain a healthy balance between work and personal life. When I'm not with my family, I often go for a jog while listening to music and watching the sunset over Seoul—a simple yet inspiring routine that helps me clear my mind. Interestingly, some of my best research ideas have emerged during these quiet, reflective moments.
Another important part of my downtime is engaging in conversations with fellow researchers and colleagues. While we sometimes chat casually about our lives, these discussions frequently evolve into deep, thought-provoking exchanges about science. In many cases, collaborative brainstorming has led to new directions in our research or sparked ideas for joint projects. I truly value these interactions, as they help keep my thinking dynamic and connected to the broader scientific community.
MH: Can you share one piece of career-related advice or wisdom with other early career scientists?
EL: One piece of advice I received early in my career, which continues to guide me, came from my PhD advisor. Whenever I approached a new or unfamiliar research topic, he would ask, “Have you read 100 papers on it yet?” At first, it sounded daunting—but I came to understand that immersing yourself deeply in a field is the fastest way to gain expertise. Even if the topic feels distant at first, there comes a moment when the concepts start to connect, and the once unfamiliar becomes familiar. As an early career scientist myself, I still face the fear of stepping into new and complex areas. But each time I’ve chosen to take on that challenge—rather than waiting until I felt perfectly prepared—it has opened up meaningful opportunities and unexpected insights. So my advice is: don’t hesitate too long. If you feel uncertain, that's exactly the right moment to start. The earlier you commit to the challenge, the sooner you’ll grow from it.
References
- J. Sung,
et al.
, Adv. Sci., 2024, 11, 2400304 CrossRef CAS PubMed
.
- H. Jang,
et al.
, Mater. Horiz., 2024, 11, 4638–4650 RSC
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