The University of Electronic Science and Technology of China has achieved new breakthroughs in the field of new sensing and precision testing

On January 19, 2023, Beijing time, Professor Cheng Yuhua’s research group from the Institute of Testing Technology and Instrumentation of the University of Electronic Science and Technology of China, together with Tobin J. Mark and Antonio Facchetti of Northwestern University, published “Vertical organic electrochemical transistors for complementary circuits” in the international authoritative journal Nature The latest research results in organic electrochemical transistors and their complementary circuits were published.

In this study, a new vertical structure based on ultraviolet curing channel is proposed for the first time for the source of test data, which solves the worldwide problem of large-scale and reliable preparation of high-performance electrochemical transistors, and is a major breakthrough in the field of new sensing and precision testing.

Huang Wei, School of Automation Engineering, University of Electronic Science and Technology of China, is the first author of the paper, Cheng Yuhua, Tobin J. Marks and Antonio Facchetti are co-corresponding authors, the School of Automation Engineering of University of Electronic Science and Technology of China is the first completion unit, and Northwestern University, Yunnan University, Zhejiang University, etc. are cooperative participants.

Organic electrochemical transistors (OECTs) and their circuits can be widely used in next-generation smart sensing, bioelectronics, wearable electronics, and artificial neuro-state electronics due to their ultra-low drive voltage (<1 V), low power consumption (<1 μW), high transconductance (>10 mS), and biocompatibility. However, the current OECT based on conventional planar structure still has a series of problems, including poor device stability, slow electrochemical reaction and switching speed, low integration density, and very poor N-type device performance, which greatly limits its further development and integration applications.

Figure 1: Schematic diagram of conventional planar structure and vertical structure and vertical stacking circuit diagram of this paper

Faced with the above challenges, the research team used a new mechanism of ion shift enhancement under nano-confinement and adopted an original vertical structure, that is, the channel between the vertically stacked dense source-drainage gold electrodes is composed of a polymer semiconductor with electrochemical activity and another electrochemically stable and lithographic polymer insulator, so as to realize an OECT with highly matched P/N type performance that can be prepared on a large scale, effectively overcoming a series of problems in the aforementioned OECT.

Figure 2: Structural characterization of vOECT devices and their performance compared to literature data.

With current densities greater than 1 kA/cm2, up to 0.4 S transconductance, switching rates faster than 1 ms, and more than 50,000 stable cycles at drive voltages below 0.7 V, this vertical OECT (vOECT) surpasses existing OECTs in device performance. Based on this, the three-dimensional vertically stacked complementary circuit can be further constructed, and the circuit integration density can be further improved on a smaller unit size. It has a voltage gain of nearly 150 at 0.7 V drive voltage, which is much higher than the various OECT-based inverters reported so far. The vOECT can also be integrated into more complex circuits such as oscillators and various logic gates.

Figure 3: A vertical circuit based on vOECT and its output characteristics

In this study, the index improvement of transconductance in P-type and N-type OECT was more than 10 times and nearly 1000 times, respectively, and the cycle stability of the highest thousand times in N-type OECT was increased to more than 50,000 times, and the P/N-type OECT was comprehensively surpassed in terms of transconductance, stability, switching rate, integrated density, preparation cost and process reliability. The research results will open up new detection/monitoring/processing methods and system solutions for many applications, play an important role in the fields where small-size, high-transconductance, low-power intelligent sensing components are urgently needed (such as early disease diagnosis, health management, brain-computer interface, implantable wearable electronics, functional repair and enhancement, and flexible intelligent robots, etc.), and provide new design concepts for the expansion of the next generation of flexible stretchable integrated circuits.

The Institute of Testing Technology and Instruments of the University of Electronic Science and Technology of China is a designated backbone research and development unit of national electronic testing instruments and a national standard formulation unit for general electronic testing instruments. Under the leadership of Professor Wang Houjun and Professor Huang Jianguo, the team has formed a complete testing technology chain from device, machine to system through the independent innovation system of industry-university-research integration, and has produced a number of internationally advanced advanced technology achievements that fill the domestic gap. In recent years, the team has strived to open up new sensor directions, continuously promoted high-display research results in response to major national needs, published important original achievements in top international academic journals for many times, won a number of important scientific and technological awards including the National Technological Invention Award, Ho Leung Ho Lee Science and Technology Innovation Award, and Science Exploration Award, and was selected as a national science and technology innovation team. This study further solves the key technology of neck in the field of design and preparation of organic electrochemical transistors in China, which is a major breakthrough in the field of new sensor devices, highlighting the international leading role of the school and team in this field. (Source: Science Network)

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