Dazhen Huang

Flexible suspended gate organic thin-film transistors for ultra-sensitive pressure detection

The utilization of organic devices as pressure-sensing elements in artificial intelligence and healthcare applications represents a fascinating opportunity for the next-generation electronic products. To satisfy the critical requirements of these promising applications, the low-cost construction of large-area ultra-sensitive organic pressure devices with outstanding flexibility is highly desired. Here we present flexible suspended gate organic thin-film transistors (SGOTFTs) as a model platform that enables ultra-sensitive pressure detection. More importantly, the unique device geometry of SGOTFTs allows the fine-tuning of their sensitivity by the suspended gate. An unprecedented sensitivity of 192 kPa−1, a low limit-of-detection pressure of <0.5 Pa and a short response time of 10 ms were successfully realized, allowing the real-time detection of acoustic waves. These excellent sensing properties of SGOTFTs, together with their advantages of facile large-area fabrication and versatility in detecting various pressure signals, make SGOTFTs a powerful strategy for spatial pressure mapping in practical applications.

Flexible and self-powered temperature–pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature–pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of <0.1 K and a high-pressure-sensing sensitivity of up to 28.9 kPa−1. More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Flexible n-Type High-Performance Thermoelectric Thin Films of Poly(nickel-ethylenetetrathiolate) Prepared by an Electrochemical Method.

Flexible thin films of poly(nickel-ethylenetetrathiolate) prepared by an electrochemical method display promising n-type thermoelectric properties with the highest ZT value up to 0.3 at room temperature. Coexistence of high electrical conductivity and high Seebeck coefficient in this coordination polymer is attributed to its degenerate narrow-bandgap semiconductor behavior.

Device Engineered Organic Transistors for Flexible Sensing Applications

Organic thin-film transistors (OFETs) represent a promising candidate for next-generation sensing applications because of the intrinsic advantages of organic semiconductors. The development of flexible sensing devices has received particular interest in the past few years. The recent efforts of developing OFETs for sensitive and specific flexible sensors are summarized from the standpoint of device engineering. The tuning of signal transduction and signal amplification are highlighted based on an overview of active-layer thickness modulation, functional receptor implantation and device geometry optimization.

Specific and Reproducible Gas Sensors Utilizing Gas‐Phase Chemical Reaction on Organic Transistors

Utilizing a textbook reaction on the surface of an organic active channel, achieves sensitive detection of HCl, NH3 and NO2, with good selectivity, excellent reproducibility, and satisfactory stability. These results reveal gas-phase reaction assisted detection as a unique and promising approach to construct practical applicable gas sensors with typical organic transistors.

Low-bandgap thieno[3,4-c]pyrrole-4,6-dione-polymers for high-performance solar cells with significantly enhanced photocurrents

Low-bandgap thieno[3,4-c]pyrrole-4,6-dione-polymers with proximal and distal configurations were synthesized for polymer solar cells. Photovoltaic performance depends on the orientation of the fused thiophene subunits, which is related to the different semiconducting properties and phase separation. Without special device treatments, P3 showed power conversion efficiencies of up to 7.50% with the highest short-circuit current (Jsc = 18.2 mA cm−2) so far reported for TPD polymers.

Solution-sheared ultrathin films for highly-sensitive ammonia detection using organic thin-film transistors

The solution-shearing technique is utilized to fabricate large-area, ultrathin and continuous films of 1,4-bis((5′-hexyl-2,2′-bithiophen-5-yl)ethynyl)benzene (HTEB) for high-performance organic thin-film transistors (OTFTs), based on which highly sensitive, highly selective and reversible gas sensors exhibit outstanding response to NH3, with detection limit as low as 100 ppb.

Bismuth Interfacial Doping of Organic Small Molecules for High Performance n‐type Thermoelectric Materials

Development of chemically doped high performance n-type organic thermoelectric (TE) materials is of vital importance for flexible power generating applications. For the first time, bismuth (Bi) n-type chemical doping of organic semiconductors is described, enabling high performance TE materials. The Bi interfacial doping of thiophene-diketopyrrolopyrrole-based quinoidal (TDPPQ) molecules endows the film with a balanced electrical conductivity of 3.3 S cm(-1) and a Seebeck coefficient of 585 μV K(-1) . The newly developed TE material possesses a maximum power factor of 113 μW m(-1)  K(-2) , which is at the forefront for organic small molecule-based n-type TE materials. These studies reveal that fine-tuning of the heavy metal doping of organic semiconductors opens up a new strategy for exploring high performance organic TE materials.

A Dual‐Organic‐Transistor‐Based Tactile‐Perception System with Signal‐Processing Functionality

Organic-device-based tactile-perception systems can open up new opportunities for the next generation of intelligent products. To meet the critical requirements of artificial perception systems, the efficient construction of organic smart elements with integrated sensing and signal processing functionalities is highly desired, but remains a challenge. This study presents a dual-organic-transistor-based tactile-perception element (DOT-TPE) with biomimetic functionality by the construction of organic synaptic transistors with integrated sensing transistors. The unique geometry of the DOT-TPE permits instantaneous sensing of pressure stimuli and synapse-like processing of an electric signal in a single element. More importantly, these organic-transistor-based tactile-perception elements can be built into arrays to serve as bionic tactile-perception systems. The combined biomimetic functionality of tactile-perception systems, together with their promising features of flexibility and large-area fabrication, makes this work represent a step forward toward novel e-skin devices for artificial intelligence.

Sensitive Flexible Magnetic Sensors using Organic Transistors with Magnetic-Functionalized Suspended Gate Electrodes.

Utilizing a magnetic-functionalized suspended gate with combined features of outstanding conductivity, flexibility, and magnetic properties, flexible magnetic sensor based on an organic field-effect transistor (OFET), with a high sensitivity of 115.2% mT(-1) is demonstrated. Gate engineering enables the sensing devices to possess promising applications for flexible touchless switches and spatiallyresolved magnetic-imaging elements.