National Taiwan University:Internationally Recognized Breakthrough in Organic Photonic FET Memory

A monumental breakthrough was made by Professor Wen-Chang Chen’s research team of the Department of Chemical Engineering and Advanced Research Center for Green Materials Science and Technology at NTU (ARC-CMST, NTU). Funded by the Higher Education SPROUT project of MOE and MOST, Prof. Chen and his team developed charge transfer-based supramolecular electrets in high-performance next-generation organic photonic memory devices, featuring unprecedented high responsive speed and long-term stability. The research article, published in October 2021, made the inside back cover of Advanced Functional Materials, an international top-tier science journal.

Prof. Chen’s team adopted a donor-acceptor type structure that effectively forms charge-transfer supramolecules as photoresponsive electrets for charge storage. The photogenerated excitons first erase the charges written in the field; then, upon retention of the reverse recovery charge in the charge-transfer complex, they achieve the read-write properties of a memory. Moreover, the spectra of the semiconductor and electret layers render the device a multiband photoresponsive range with a high memory on/off ratio of over 106 after 104s.

Extensive research has been conducted on organic optoelectronic devices owing to their low cost and mass-production potential; however, voltage restrictions and stability are areas for improvement. Committed to the development of memory materials and devices, Prof. Chen proposed the novel concept of using photoresponsive inorganic and organic floating gates as well as using light as an impetus for electric responses in memory devices in 2017. His collaboration with Prof. Toshifumi Satoh of Hokkaido University also identified organic nanomaterials that can be employed to achieve high-performance photoresponsive memory devices. There is great potential for applications of photonic memory devices, such as image-identification by artificial retinas. Photonic memory could also be applied to wearable devices in combination with biomaterials that are inherently light-sensitive and compatible with the human body.

The breakthrough of using charge-transfer supramolecules in organic photonic FET memory devices has expanded the frontiers of optoelectronic applications. This cutting-edge material design and blending for devices offer a new perspective to the development of next-generation organic photo-driven memory.

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