Nanotechnologies / Materials
Remote medical service / Digital healthcare, IoT device, AR/VR/MR technology

High-precision electrical characteristics control forflexible organic electronic circuits
Department of Advanced Electron Devices, SANKEN (The Institute of Scientific and Industrial Science)Specially Appointed Associate Professor Takafumi Uemura

https://researchmap.jp/Takafumi_Uemura

Professor Tsuyoshi Sekitani

https://researchmap.jp/TSS

Nanotechnologies / Materials

Abstract
Ultra-lightweight and flexible electronic devices have beenstudied to build imperceptible wearable sensors, aiming to realize a sustainable health society realized with digital healthcaretechnology. This is because imperceptible wearable sensors area new device technology that makes it possible to monitor a person’s health over time and quickly detect health status problems.
In this research, we have successfully changed the characteristicsof flexible integrated circuits by using a polymer material whosemolecular structure changes upon light irradiation as an insulating
layer of organic transistors. This technology allows the electricalcharacteristics of organic electronic circuits to be freely changed
by light irradiation. This technology can significantly improve thepower consumption performance of flexible transistor circuits.

▍ Background & Results
Our research group has been developing flexible organic circuits utilizing organic electronic materials with high mechanicalflexibility. However, flexible sensor devices that realize biologicalsignal measurement consist of multiple electronic functions, suchas switching and signal processing circuits. Therefore, the development of technology to control the electrical characteristics ofindividual transistors was required to obtain the desired deviceperformance. In this study, the research group has developed atechnology to control electrical characteristics by light irradiation.
With this technology, the threshold voltage, applied gate voltage
at which the organic transistor switches ON and OFF, can be arbitrarily adjusted in the range of -1.5 V to +0.2 V. The light-based
technology also has an excellent two-dimensional spatial resolution for characteristic control. In this study, it was confirmed thatmolecular structure changes can be induced with an accuracy ofapproximately 18 µm. Moreover, this technology can be applied tomanufacture smaller circuits with higher integration levels by theimprovement of light irradiation conditions. In addition, it is becoming clear that this technology can be applied to p-type and n-typetransistors. It enables complementary circuits that achieve low
power consumption through precise control of electrical characteristics. Specifically, it is possible to fabricate the different functionalgroups on the same substrate freely. For example, low-power andhigh-speed circuit groups are integrated on the same substrate.

▍ Significance of the research and Future perspective
This research result shows that the characteristics of flexible
organic electronic circuits can be controlled by a simple processusing light irradiation and fewer materials compared to conventional techniques. This technology is expected to enable higher performance of flexible electronic circuits and be utilized as a sensing
technology for many kinds of object in real space. It will help torealize imperceptible wearable biomedical sensors, an essential
technology in future remote medical service and digital health care.
P a t e n t Japanese Patent No. 6629887
Taguchi, Koki; Uemura, Takafumi; Sekitani, Tsuyoshi et al. Heterogeneous Functional Dielectric Patterns for Charge-Carrier Modulation in Ultraflexible
Tr e a t i s e
Organic Integrated Circuits. Advanced Materials. 2021, 33, 2104446, doi: 10.1002/adma.202104446
https://resou.osaka-u.ac.jp/ja/research/2021/20210921_2
URL
https://wakasapo.nedo.go.jp/seeds/seeds-2020/
K e y w o r d flexible electronics, wearable electronics, organic semiconductor