Breaking the Wall of Printing Transparent Materials

Breaking the Wall of Printing Transparent Materials

Global Call 2026 Finalist Interview: Engineering & Technology

Dangyuan Lei is Professor of Materials Science and Engineering, Professor of Physics (joint appointment) and Deputy Director of the Centre for Functional Photonics at City University of Hong Kong, and was Provost's Visiting Professor of Physics at Imperial College London. He is interested in quantum, nonlinear nano-photonics and ultrafast spectroscopy of exciton-photon-phonon coupling in 2D semiconductors, with particular interest in nanophotonics-empowered advanced manufacturing and thermal management.

Which wall does your research or project break?  

Traditionally, the fabrication of high-density microelectronic and optoelectronic devices, especially those relying on transparent functional materials like metal oxides, has been severely constrained by indirect and multi-step patterning processes, such as photolithography and nanoimprint lithography. These workflows are not only complex, costly and difficult to scale, but also require energy-intensive vacuum processing and high-temperature post-annealing to crystallize the materials. On the other hand, while direct laser writing offers maskless flexibility, it is typically restricted to photosensitive materials and fails when applied to highly transparent materials due to their poor light absorption.

Our research breaks through these limitations by introducing plasmonic photothermal printing, a fundamentally new manufacturing strategy that combines femtosecond laser excitation with plasmonic nanostructures to generate highly localized and transient photothermal heating. Compared with conventional direct laser heating, this approach dramatically enhances photothermal conversion efficiency, enabling precise in-situ nucleation, crystallization and patterning of solution-processed transparent metal oxides at room temperature under ambient conditions. By eliminating the need for photoresists, vacuum environments, and high-temperature post-annealing, it enables high-throughput, low-energy-consumption manufacturing of functional electronic components with integration densities up to 48,400 transistors/cm², overcoming the integration-density bottleneck imposed by thermal diffusion and heat accumulation in conventional thermal annealing processes. Furthermore, the excellent spatial uniformity, high device reproducibility, and compatibility with solution-processed materials provide a scalable platform for the heterogeneous integration of complex multilayer electronic and optoelectronic systems, paving the way toward next-generation energy-efficient microelectronics manufacturing.

What is the main goal of your research or project?

The main goal of our research is to establish a scalable, high-resolution, and energy-efficient manufacturing platform for next-generation electronic and optoelectronic devices by fundamentally rethinking how transparent functional materials are fabricated. Our research focuses on achieving precise spatial and temporal control over the decomposition, nucleation, crystallization, and phase transformation of solution-processed transparent metal oxides at the microscale, while operating entirely at room temperature under ambient atmospheric conditions. By leveraging the highly localized and transient photothermal heating generated by femtosecond-laser-excited plasmonic silver nanowires, we enable the in-situ synthesis and direct patterning of high-performance metal-oxide thin films in a single manufacturing step, eliminating the need for vacuum processing, photoresists, and high-temperature post-annealing.

A critical milestone of our research is that this simplified direct-printing strategy delivers high manufacturing efficiency without compromising device performance, fabrication precision, or integration density. We demonstrate thin-film transistor arrays with densities of up to 48,400 transistors/cm², achieving electrical performance comparable to state-of-the-art vacuum-based fabrication techniques. By engineering plasmonic light–matter interactions and localized heat transport, our approach further improves printing uniformity, device reproducibility, and manufacturing reliability while significantly reducing fabrication complexity and energy consumption. Beyond advancing a new fabrication technique, our work establishes a practical and scalable manufacturing paradigm for the heterogeneous integration of multifunctional electronic and optoelectronic systems, opening new opportunities for flexible electronics, advanced sensing, displays, and intelligent photonic devices.

What impact does your research or project have on society?

Our research has the potential to deliver both technological and societal benefits by enabling a more sustainable and scalable approach to manufacturing next-generation electronic and optoelectronic devices. By replacing conventional high-temperature, vacuum-based fabrication with room-temperature plasmonic photothermal printing under ambient conditions, our approach significantly reduces energy consumption, manufacturing complexity, material waste, and the associated carbon footprint of micro- and nano-fabrication. This capability can accelerate the commercialization of high-density integrated circuits, active-matrix displays, flexible and wearable electronics, intelligent sensors, and other emerging technologies, making advanced electronic systems more accessible, affordable, and easier to manufacture. Beyond improving manufacturing efficiency, the technology provides a practical pathway towards the heterogeneous integration of multifunctional electronic and optoelectronic systems while supporting the transition to greener manufacturing practices. By combining advances in nanophotonics with sustainable manufacturing, our work demonstrates how fundamental research can address real industrial challenges, strengthen the competitiveness of advanced manufacturing, and contribute to the development of a more energy-efficient and environmentally responsible electronics industry.

What advice would you give to young scientists or students interested in pursuing a career in research, or to your younger self starting in science?

When you start a research project, do not try to solve or disrupt an entire field at once. Instead, identify a small and specific scientific question, and gradually explore it in depth. A good research project often begins with understanding what has already been achieved in the field. Therefore, reading and studying the literature carefully is essential. By understanding the history and development of a research area, you can better identify the limitations of existing knowledge, recognize the importance of your own work, and discover where meaningful innovation can be made.

Research is a long-term process that requires both efficiency and dedication. While good time management is important, truly impactful discoveries often come from going deeper into a problem and continuously learning new knowledge along the way. The more deeply you explore a topic, the more challenges and questions you will encounter, and addressing them requires patience, curiosity, and sustained effort. Do not be afraid of difficulties; they are often where the most valuable scientific insights emerge.

At the same time, maintaining a healthy and positive state is equally important for a successful research career. Scientific research requires creativity and persistence, which depend on a balanced mindset and physical well-being. Simple activities such as running, hiking, or spending time with your teammates can help you relax and recharge. A good researcher should not only work hard but also learn how to maintain long-term enthusiasm and motivation for discovery.


What inspired you to be in the profession you are today?

I have been fascinated by mathematics since my elementary school and then by physics since my secondary school. Their beauty of physics and mathematics has inspired me to carry our both fundamental and applied research in optical physics and materials.
 

What is one surprising fact about your research or project that people might not know?

One surprising fact about our plasmonic printing research is that it miraculously transforms useless and even harmful energy waste to useful and highly localized, transient photothermal heating for advanced optical manufacturing.

What’s the most exciting moment you've experienced over the course of your research or project?

The most exciting moment over the course of carrying out the plasmonic printing project is the realization of in-situ synthesis and direct patterning of high-performance metal-oxide thin films and subsequent high-throughput, low-energy-consumption, room-temperature manufacturing of all-metal-oxide based transistors with a record integration density.