Linrun Feng

Bio: Linrun Feng is an academic researcher from Shanghai Jiao Tong University. The author has contributed to research in topics: Thin-film transistor & Transistor. The author has an hindex of 16, co-authored 53 publications receiving 752 citations.

Unencapsulated Air-stable Organic Field Effect Transistor by All Solution Processes for Low Power Vapor Sensing.

Abstract: With its excellent mechanical flexibility, low-cost and low-temperature processing, the solution processed organic field-effect transistor (OFET) is a promising platform technology for developing ubiquitous sensor applications in digital health, environment monitoring and Internet of Things. However, a contradiction between achieving low voltage operation and having stable performance severely hinder the technology to become commercially viable. This work shows that, by reducing the sub-gap density of states (DOS) at the channel for low operation voltage and using a proper low-k non-polar polymer dielectric layer, such an issue can be addressed. Stable electrical properties after either being placed for weeks or continuously prolonged bias stressing for hours in ambient air are achieved for all solution processed unencapsulated OFETs with the channel being exposed to the ambient air for analyte detection. The fabricated device presents a steep subthreshold swing less than 100 mV/decade, and an ON/OFF ratio of 10(6) at a voltage swing of 3 V. The low voltage and stable operation allows the sensor made of the OFET to be incorporated into a battery-powered electronic system for continuously reliable sensing of ammonia vapor in ambient air with very small power consumption of about 50 nW.

Ultralow-Voltage Solution-Processed Organic Transistors With Small Gate Dielectric Capacitance

Abstract: In this letter, ultralow-operation-voltage (<; 2 V) solution-processed organic thin-film transistors were achieved at small gate dielectric capacitance of only 12.2 nF/cm2 in the bottom-gate bottom-contact configuration. In the devices, 6,13-bis(triisopropylsilylethynyl)-pentacene blended with polystyrene was used as the channel layer, and ultraviolet cross-linked polyvinyl alcohol was used as the gate dielectric layer. The maximum processing temperature was 100°C. The devices showed promising performance with a mobility value of about 1.0 cm2/( V·s), a subthreshold swing of about 100 mV/dec, and negligible hysteresis. The mechanism of achieving such a low operation voltage without needing large gate dielectric capacitance for the devices was discussed.

Solution-Processed Zinc Oxide Thin-Film Transistors With a Low-Temperature Polymer Passivation Layer

Abstract: Bottom-gate top-contact zinc oxide (ZnO) thin-film transistors were fabricated with a low annealing temperature (150 °C) using ammine-hydroxo zinc precursors. The unpassivated devices present profound hysteresis in the measured current-voltage characteristics and a negative output conductance, which were attributed to the interaction of back surface with the oxygen molecules in the ambient atmosphere. To suppress the ambient influence without impacting the device's intrinsic performance, a simple low-temperature (75 °C ) solution-based passivation approach with polydimethylsiloxane was developed. The passivated devices present typical field-effect transistor behaviors of greatly improved device performance.

Inkjet printed fine silver electrodes for all-solution-processed low-voltage organic thin film transistors

Abstract: Inkjet printed silver (IJP Ag) source/drain (S/D) and gate electrodes were incorporated into a bottom-gate bottom-contact organic thin film transistor (OTFT) architecture to develop all-solution-processed low voltage OTFTs. With well controlled ink wetting on a cross-linked polyvinyl-alcohol surface, IJP Ag S/D electrode pairs were fabricated with controllable short channels down to 20 μm using a Dimatix 2831 inkjet printer with a 10 pL cartridge, and formed good contacts with the organic semiconductor layer. IJP gate electrodes with a low flat surface profile were also achieved to obtain OTFTs of high quality gate dielectric layer for low leakage current. The fabricated low voltage all-solution-processed OTFTs present good device performance with a low operation voltage below 2 V, a mobility of 0.3 cm2 V−1 s−1, and an ON/OFF current ratio larger than 104.

High- k Gate Dielectrics for Emerging Flexible and Stretchable Electronics

Abstract: Recent advances in flexible and stretchable electronics (FSE), a technology diverging from the conventional rigid silicon technology, have stimulated fundamental scientific and technological research efforts. FSE aims at enabling disruptive applications such as flexible displays, wearable sensors, printed RFID tags on packaging, electronics on skin/organs, and Internet-of-things as well as possibly reducing the cost of electronic device fabrication. Thus, the key materials components of electronics, the semiconductor, the dielectric, and the conductor as well as the passive (substrate, planarization, passivation, and encapsulation layers) must exhibit electrical performance and mechanical properties compatible with FSE components and products. In this review, we summarize and analyze recent advances in materials concepts as well as in thin-film fabrication techniques for high-k (or high-capacitance) gate dielectrics when integrated with FSE-compatible semiconductors such as organics, metal oxides, quantum...

Chemical and Biomolecule Sensing with Organic Field-Effect Transistors

Abstract: The strong and controllable chemical sensitivity of organic semiconductors (OSCs) and the amplification capability of transistors in circuits make use of OSC-based field-effect transistors compelling for chemical sensors. Analytes detected and assayed range from few-atom gas-phase molecules that may have adverse health and security implications to biomacromolecules (proteins, nucleic acids) that may be markers for physiological processes and medical conditions. This review highlights recent progress in organic field-effect transistor (OFET) chemical sensors, emphasizing advances from the past 5 years and including aspects of OSC morphology and the role of adjacent dielectrics. Design elements of the OSCs and various formats for the devices are illustrated and evaluated. Challenges associated with the present state of the art and future opportunities are also discussed.

A Circuits and Systems Perspective of Organic/Printed Electronics: Review, Challenges, and Contemporary and Emerging Design Approaches

Abstract: The often touted attractive attributes of printed/organic electronics are its mechanically flexible form-factor, low-cost, green, on-demand printing, scalability, low-power operation, and intelligence (signal processing) – ideally, the creation of intelligent lightweight electronics printed by simple ubiquitous printing processes, and integrated into new ways to exploit its mechanically flexible form-factor. Printed/Organic Electronics, now an industry on its own right and recognized as one of the key technological enablers for the Internet of Things, is largely complementary to silicon because the printed transistors are slow and the printed elements are large. The sanguine projected growth of the $29 B market today to $73 B by 2027 assumes that ‘intelligence’ (analog, mixed-signal and digital signal processing) would be realizable. Nevertheless, many of the said attributes of printed/organic electronics remain a challenge. In this paper, we exemplify this with a comprehensive and critical review and tabulation of the state-of-the art printed digital, analog, and mixed-signal circuits. We further review the application space of printed/organic electronics and the supply chain, including their classifications and delineate the associated challenges in each constituent chain. These challenges, largely unresolved, are indeed formidable, and are discussed with a critical circuits and systems perspective. Our review depicts that contemporary design philosophies and methodologies for silicon are largely inadequate for printed/organic electronics. To this end, we discuss esoteric analog and digital design philosophies and methodologies, with emphasis on co-design and co-optimization between the different constituent supply chains that may potentially circumvent the said formidable challenges, and discuss the associated penalties thereto.

Resonant-enhanced full-color emission of quantum-dot-based micro LED display technology.

Abstract: Colloidal quantum dots which can emit red, green, and blue colors are incorporated with a micro-LED array to demonstrate a feasible choice for future display technology. The pitch of the micro-LED array is 40μm, which is sufficient for high-resolution screen applications. The method that was used to spray the quantum dots in such tight space is called Aerosol Jet technology which uses atomizer and gas flow control to obtain uniform and controlled narrow spots. The ultra-violet LEDs are used in the array to excite the red, green and blue quantum dots on the top surface. To increase the utilization of the UV photons, a layer of distributed Bragg reflector was laid down on the device to reflect most of the leaked UV photons back to the quantum dot layers. With this mechanism, the enhanced luminous flux is 194% (blue), 173% (green) and 183% (red) more than that of the samples without the reflector. The luminous efficacy of radiation (LER) was measured under various currents and a value of 165 lm/Watt was recorded.

Current Status and Opportunities of Organic Thin-Film Transistor Technologies

Abstract: Attributed to its advantages of super mechanical flexibility, very low-temperature processing, and compatibility with low cost and high throughput manufacturing, organic thin-film transistor (OTFT) technology is able to bring electrical, mechanical, and industrial benefits to a wide range of new applications by activating nonflat surfaces with flexible displays, sensors, and other electronic functions. Despite both strong application demand and these significant technological advances, there is still a gap to be filled for OTFT technology to be widely commercially adopted. This paper provides a comprehensive review of the current status of OTFT technologies ranging from material, device, process, and integration, to design and system applications, and clarifies the real challenges behind to be addressed.