Materials Horizons Emerging Investigator Series: Prof. Himchan Cho, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea

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Abstract

Our Emerging Investigator Series features exceptional work by early-career researchers working in the field of materials science.

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Prof. Himchan Cho (https://orcid.org/0000-0001-6372-5787) is an Associate Professor in the Department of Materials Science and Engineering (DMSE) at the Korea Advanced Institute of Science and Technology (KAIST). Prof. Cho received his BS (2012) and PhD (2016) degree in MSE from the Pohang University of Science and Technology (POSTECH), Republic of Korea. After working at Seoul National University (2016–2018) and the University of Chicago (2018–2021) as a postdoctoral scholar, he joined KAIST DMSE as a faculty member in 2021. His contributions to the field have been acknowledged by numerous honors, including the Korea Toray Fellowship (2025), Top 100 National R&D achievements (2024), KAIST's Top 10 Research Achievements (2023), KIM Young Researcher in Material Innovation (2023), POSCO Science Fellowship (2022), and POSTECH Alumni President Award (2017). Prof. Cho's research focuses on optoelectronic nanomaterials and devices, including metal halide perovskites, colloidal quantum dots, direct optical lithography, light-emitting diodes, color conversion layers, optical memory/neuromorphic devices, and infrared photodetectors.

Read Himchan Cho's Emerging Investigator Series article ‘Interface-modified NiMgO_x layers with dibenzocarbazole molecules for high-efficiency perovskite light-emitting diodes’ ( https://doi.org/10.1039/D5MH01949D ) and read more about him in the interview below:

MH: Your recent Materials Horizons Communication presents a new strategy for improving perovskite light-emitting diodes (PeLEDs) by using a dibenzocarbazole-functionalized phosphonic acid interlayer (4PADCB). How has your research evolved from your first article to this most recent article and where do you see your research going in future?

HC: My first PeLED paper was published in 2014 ¹ and focused on PeLEDs covering a wide range of visible colors by using a PEDOT:PSS-based hole injection layer, termed Buf-HIL, which effectively suppresses interfacial quenching of the perovskite emission layer. At that time, the external quantum efficiency was only around 0.125%. Since then, through subsequent studies, I have developed various strategies for high-efficiency PeLEDs, such as the nanocrystal pinning process² and quasi-2D perovskite structures,³ which led to substantial improvements in device efficiency.

More recently, I have become increasingly convinced that inorganic hole injection layers, particularly NiMgO_x, can play a crucial role in achieving highly efficient and stable PeLEDs. My current research interests include developing such inorganic hole injection layers with carefully designed interfacial modifiers, and I see the present Materials Horizons paper as an important first step in this direction in my research group. Looking ahead, I expect our research to expand toward different emission colors as well as tandem PeLED architectures.

MH: What aspect of your work are you most excited about at the moment?

HC: For this Materials Horizons paper, I am excited about the detailed analysis of dual-side interfacial passivation induced by 4PADCB at the interface between the NiMgO_x layer and the perovskite emission layer in PeLEDs.

Alongside this work, our group is actively pursuing several other research directions. Among them, one area that currently excites me the most is the development of nondestructive direct optical lithography for perovskite and quantum dot emitters. Instead of relying on conventional polymeric photoresists, we employ photosensitive ligands or functional additives that directly participate in the photochemical process, enabling lithographic patterning while preserving the intrinsic optoelectronic properties of the emitters.

MH: In your opinion, what are the most important questions to be asked/answered in this field of research?

HC: One of the key questions is whether the operational stability of PeLEDs, across red, green, and blue emission colors, can be improved to levels comparable to InP-based quantum dot LEDs or OLEDs. Closely related to this is the question of what the ultimate device architecture should look like to achieve this goal, and which passivation strategies are most ideal for simultaneously improving device efficiency and operational stability.

MH: What do you find most challenging about your research?

HC: Improving device efficiency almost always requires a large number of optimization experiments, which is inherently challenging. Maintaining highly consistent experimental conditions across these extensive studies, especially under varying environmental factors such as temperature, humidity, and glovebox conditions, is also a significant challenge.

MH: In which upcoming conferences or events may our readers meet you?

HC: I plan to attend and present at the 2026 MRS Spring Meeting and MATSUS Spring 2026. I am also organizing a symposium related to perovskites and colloidal quantum dots at the 2026 MRS Fall Meeting.

MH: How do you spend your spare time?

HC: I usually spend weekends with my family, going shopping together or watching movies.

MH: Can you share one piece of career-related advice or wisdom with other early career scientists?

HC: To sustain long-term motivation and productivity in research, I think it is essential to have a personal way to relieve stress. Whether it is exercise or another activity, finding a healthy outlet outside the lab can make a significant difference over the course of a scientific career.

References

1. Y. H. Kim, H. Cho, J. H. Heo, T.-S. Kim, N. Myoung, C.-L. Lee, S. H. Im and T.-W. Lee, Adv. Mater., 2015, 27, 1248.
2. H. Cho, S.-H. Jeong, M.-H. Park, Y.-H. Kim, C. Wolf, C.-L. Lee, J. H. Heo, A. Sadhanala, N. Myoung, S. Yoo, S. H. Im, R. H. Friend and T.-W. Lee, Science, 2015, 350, 1222.
3. J. Byun, H. Cho, C. Wolf, M. Jang, A. Sadhanala, R. H. Friend, H. Yang and T.-W. Lee, Advanced Materials, 2016, 28, 7515.

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