Bio-inspired metallic networks as flexible transparent conductors: from lab to pilot scale
Prof. Gao Jinwei
South China Normal University
Date & Time
Room 7-37, Haking Wong Building, HKU
Transparent conductors (TC) are critical materials for modern optoelectronic applications ranging from light emitting diodes, to displays (including touch-screen and flexible), to solar cells, to wearable electronics. In lighting and solar applications TC must be highly conducting in order to lower the ohmic losses. In display applications, microscopic transparency and lack of haze is required, as well as there is a need for mechanical flexibility in the case of flexible displays and wearable electronics. A chemical stability is also a must. These new requirements put pressure on the current standard material, indium tin oxide (ITO), which has overall good electro-optic performance and chemical stability, but is resistive, brittle and quite expensive. Recently, a new generation of TC materials emerged as a possible replacement for ITO, which can be tailored to satisfy all the above requirements. This talk will review such materials including our metallic networks, which have been inspired by nature. In one example, we developed the quasi-fractal hierarchical TC based on the self-cracking network combined with nanowires. This network TC has record high conductivity and simultaneously excellent transparency, and thus is ideal for lighting and solar applications. We have shown, that it is the plasmonic refraction of nanowires, which allows for the network increased transparency beyond the classic, shading limit. In addition, this network TC is mechanically flexible, and can be made inexpensively with wet chemical processing only. A version of this network can be used in displays, due to its low haze and low network visibility. We have very recently developed a roll-to-roll pilot production line of the self-cracking network on flexible plastic substrates with width of ~ 400 mm.
Jinwei Gao is currently Professor of South China Academy of Advanced Optoelectronics at South China Normal University. His research interests center on optoelectronic materials and devices, especially in flexible transparent conductors and the applications in modern electronics, such as, solar cells, display and sensor. He has made important contributions to the emerging nanomaterial in ITO replacement, such as cracking metallic networks, fractal metallic networks, and nature inspired electronics. He and his collaborators exploited the unique fractal structure and the transport physics to advance the field of transparent conductors and their applications in solar cells and displays. His group also developed strategies to engineer nanostructures to achieve high efficiency perovskite solar cells, 3D fractal and hierarchical structures in water splitting and special concept for solar-drived steam generation. By exploring those micro/nanoscale transport phenomena, Prof. Gao’s group is advancing a wide range of technologies such as cracking metallic transparent conductor, fractal and stretchable transparent conductor, and high effective perovskite solar cells. Prof. Gao published more than 70 technical articles, including Nature Communications, Advanced Materials, Advanced Functional Materials Advances in Physics etc. He has over 25 granted and pending patents.