High-Speed Organic Integrated Circuits and Applications

Electronic devices in the future sustainable societies require maximum function with minimum amount of constituent materials and energy cost for production. Electronic functions are often originated from two-dimensional material properties so that device components of large area and small thickness saves material consumption. The fundamental electronic functions of both analogue and digital circuits mostly rely on only a nanometer-scale thin layer at the very surface of the semiconductor material due to the very short penetration length of electric field. The presentation focuses on material bases, methods of circuit fabrication, dynamic operation of the devices, and several applications for commercialization.<br/>Recently developed ultrathin organic semiconductor single crystalline films is suitable for large-area production with low energy consumption; the films are easily formed to large area from solution at relatively low temperature at 80 degrees centigrade [1]. Extremely thin crystal films are controllably grown to a-few molecular layers with the thickness of only 10 nm, so that material cost can be highly limited. Due to a careful material design for restricting harmful molecular vibration, very high carrier mobility more than 10 cm2/Vs is achieved. Furthermore, development of technologies for printed integrated circuits provides a manufacturable process for low-cost platforms for RFID tags and sensing circuitries. Finally, a technology for large-area light-weight display sheets will be demonstrated.<br/>A dynamic transistor model is developed using device parameters such as channel length and overlap length of gate and source electrodes, so that high-frequency transistors are physically designed appropriately including charge-injection resistance [2]. A high cut-off frequency above 45 MHz is actually achieved which are composing elements of organic integrated circuits. Typical integrated circuits of approximately 500 transistors are formed. Moreover, a wireless power-supply is demonstrated using newly developed high-frequency organic rectifiers to operate an RFID tag with the NFC frequency [3].<br/>Such prospect bears increasing reality because of recent research innovations in the field of material chemistry, charge transport physics, and solution processes of printable organic semiconductors. With excellent chemical and thermal stability in recently developed new materials, we are developing simple integrated devices based on CMOS using organic p-type and inorganic n-type FETs. Particularly important are new processing technologies for continuous growth of the organic single-crystalline semiconductor “wafers” from solution and for lithographical patterning of semiconductors and metal electrodes. Successful rectification and identification are demonstrated at 13.56 MHz with printed organic CMOS circuits. Future ten-meter scale large-area display also needs to be more “two-dimensional” to save materials and save energies to carry and equip on billboards.<br/><br/>[1] S. Watanabe, J. Takeya et al., Communications Physics 1, 37 (2018); A. Yamamura, S. Watanabe, J. Takeya et al., Sci. Adv. 4, eaao5758 (2018); T. Makita, S. Kumagai, A. Kumamoto, M. Mitani, J. Tsurumi, R. Hakamatani, M. Sasaki, T. Okamoto, Y. Ikuhara, S. Watanabe, and J. Takeya, PNAS (2019).<br/>[2] T. Sawada, A. Yamamura, M. Sasaki, K. Takahira, T. Okamoto, S. Watanabe and J. Takeya, Nat. Commun. volume 11, Article number: 4839 (2020).<br/>[3] A. Yamamura, J. Takeya et. al., Adv. Electron. Mater. 3, 1600456 (2017).