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.
Abstract
N-doping plays an irreplaceable role in controlling the electron concentration of organic semiconductors thus to improve performance of organic semiconductor devices. However, compared with ...many mature p-doping methods, n-doping of organic semiconductor is still of challenges. In particular, dopant stability/processability, counterion-semiconductor immiscibility and doping induced microstructure non-uniformity have restricted the application of n-doping in high-performance devices. Here, we report a computer-assisted screening approach to rationally design of a triaminomethane-type dopant, which exhibit extremely high stability and strong hydride donating property due to its thermally activated doping mechanism. This triaminomethane derivative shows excellent counterion-semiconductor miscibility (counter cations stay with the polymer side chains), high doping efficiency and uniformity. By using triaminomethane, we realize a record n-type conductivity of up to 21 S cm
−1
and power factors as high as 51 μW m
−1
K
−2
even in films with thicknesses over 10 μm, and we demonstrate the first reported all-polymer thermoelectric generator.
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.
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.
Recent efforts in developing highly sensitive and specific flexible sensors in terms of active‐layer thickness modulation, functional receptor implantation, and device geometry optimization are briefly summarized with an outlook on future requirements.
Two-dimensional transition metal dichalcogenides (TMDs) have attracted lots of interest because of their potential for electronic and optoelectronic applications. Atomically thin TMD flakes were ...believed capable to scroll into nanoscrolls (NSs) with distinct properties. However, limited by mechanical strength and chemical stability, production of high-quality TMD NSs remains challenging. Here, we scroll chemical vapor deposition-grown monolayer TMD flakes into high-quality NSs in situ in 5 s with a nearly 100% yield by only one droplet of ethanol solution. An obvious photoluminescence is demonstrated in NSs and the self-encapsulated structure makes NSs more insensitive to external factors in optical and electrical properties. Furthermore, based on the internal open topology, NSs hybridized with a variety of functional materials have been fabricated, which is expected to confer TMD NSs with additional properties and functions attractive for potential application.
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.
To achieve efficient n-type doping, three dopants, 2-Cyc-DMBI-H, (2-Cyc-DMBI)2, and (2-Cyc-DMBI-Me)2, with precisely regulated electron-donating ability were designed and synthesized. By doping with ...a small-molecule 2DQTT-o-OD with high electron mobility, an unexpectedly high power factor of 33.3 μW m–1 K–2 was obtained with the new dopant (2-Cyc-DMBI-Me)2. Notably, with the intrinsically low lateral thermal conductivity of 0.28 W m–1 K–1, the figure of merit was determined to be 0.02 at room temperature. Thus, we have demonstrated that small molecules with high electron mobility and low-lying LUMO energy levels can achieve high doping efficiency and excellent thermoelectric properties by doping with n-type dopants featuring highly matched energy levels and excellent miscibility.
Organic thermoelectric materials, which can transform heat flow into electricity, have great potential for flexible, ultra‐low‐cost and large‐area thermoelectric applications. Despite rapid ...developments of organic thermoelectric materials, exploration and investigation of promising organic thermoelectric semiconductors still remain as a challenge. Here, the thermoelectric properties of several p‐ and n‐type organic semiconductors are investigated and studied, in particular, how the electric field modulations of the Seebeck coefficient in organic field‐effect transistors (OFETs) compare with the Seebeck coefficient in chemically doped films. The extracted relationship between the Seebeck coefficient (S) and electrical conductivity (σ) from the field‐effect transistor (FET) geometry is in good agreement with that of chemically doped films, enabling the investigation of the trade‐off relationship among σ, S, carrier concentration, and charging level. The results make OFETs an effective candidate for the thermoelectric studies of organic semiconductors.
Investigation of thermoelectric properties of organic semiconductors is a fundamental issue toward effective application of high‐performance organic thermoelectric materials. It is reported on a systematic study of the thermoelectric properties for organic semiconductors via field‐effect transistors, which indicates that organic transistors should provide an effective platform to accelerate the screening of promising organic 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.
Interfacial doping for organic thermoelectrics: Bismuth interfacial doping of thiophene‐diketopyrrolopyrrole‐based quinoidal molecules results in a maximum power factor (PFmax) of 113 μW m−1 K−2. Heavy metal doping of organic semiconductors can open up a new strategy for exploring high performance organic thermoelectric materials.
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.
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