robots, [3] and biomedical devices, [4] flexible electronic devices have attracted much attention. Some flexible electronic devices can be embedded into clothing or gloves, or be mounted on body, to provide a wearable, functional, and sentient electronic system.Flexible strain sensor is one of the representative flexible electronic devices, which works by using electrical sensors built on flexible substrate with various operation modes of piezoresistive, [2] capacitive, [5] and piezoelectric type. [6] Most efforts of research and development have been focused on exploring new materials [7,8] or developing novel structures [9] to detect strain, temperature, or bimodal signal. The reliability of flexible strain sensor in harsh environments such as at ultralow or high temperatures, however, has so far received few attentions. Traditional bendable or stretchable substrate, such as polyethylene terephthalate (PET), polyimide (PI), polydimethylsiloxane (PDMS), paper, silk, and cotton cannot withstand high temperatures. As a result, there has been few thermally stable flexible strain sensors that can survive at temperatures above 200 °C. Consequently, the application of flexible strain sensors is limited in harsh conditions such as in interstellar probe, polar exploration, and petrochemical, where strain sensing at a high or low temperature is required. Flexible strain sensors have captured a lot of attention since first beingproposed. Most studies are focused on adopting new materials or developing novel structures to detect strain, temperature, and even to realize multifunction. The reliability of flexible strain sensors in harsh environments such as at low and high temperatures, however, has so far received little attention because traditional bendable or stretchable substrates, including polyethylene terephthalate, polyimide, polydimethylsiloxane, paper, silk, and cotton, cannot withstand high temperature. The poor thermostability limits their potential applications in harsh conditions such as in interstellar probes, polar exploration, petrochemical, and metal smelting. Here, a heat-resisting flexible strain sensor is shown, consists of a BaNb 0.5 Ti 0.5 O 3 film on top of a 4.5 µm thick mica substrate. The device exhibits excellent thermal stability in a wide temperature range from 20 to 773.15 K. Owing to the ultrathin mica substrate and low resistance, the device demonstrates low power consumption (0.96 µW cm −2 ), is lightweight (2.06 g cm −3 ), together with having high stability over 5000 bending cycles. This work opens a path for pressure sensors applying ceramic materials that can be used from an ultralow to a high temperature.

We performed a systematic study of the influence of environmental conditions on the electrical performance characteristics of solution-processed 2,7-dioctyl [1] benzothieno[3,2-b][1]-benzothiophene (C8-BTBT) thin-film transistors (TFTs). Four environmental exposure conditions were considered: high vacuum (HV), O 2 , N 2 , and air. The devices exposed to O 2 and N 2 for 2 h performed in a manner similar to that of the device kept in HV. However, the device exposed to air for 2 h exhibited significantly better electrical properties than its counterparts. The average and highest carrier mobility of the 70 air-exposed C8-BTBT TFTs were 4.82 and 8.07 cm 2 V -1 s -1 , respectively. This can be compared to 2.76 cm 2 V -1 s -1 and 4.70 cm 2 V -1 s -1 , respectively, for the 70 devices kept in HV. Furthermore, device air stability was investigated. The electrical performance of C8-BTBT TFTs degrades after long periods of air exposure. Our work improves knowledge of charge transport behavior and mechanisms in C8-BTBT OTFTs. It also provides ideas that may help to improve device electrical performance further.

An organic ambipolar transistor allows the integration of p-type and n-type charge carrier transport in a single device. However, the tunability of carrier polarity to meet specific requirements for practical applications is challenging and thus rarely studied. In this work, two dual-acceptor-type polymers (FuI and SeI) based on diketopyrrolopyrrole (DPP) and bithiophene imide (BTI) are reported. By varying the flanking groups of DPP (furan for FuI and selenophene for SeI) and through an ionic additive strategy, the charge carrier polarity of both polymers in organic field-effect transistors (OFETs) can be directionally tuned. Specifically, pristine polymers exhibited an ambipolar property with the μe/μh values of 2.79 for FuI and 4.9 for SeI. Notably, the average electron mobility of SeI reaches as high as 0.122 cm2 V–1 s–1. More encouragingly, with 11.76% tetrabutylammonium iodide (TBAI, mole percentage) as an additive to the FuI polymer, the μe/μh of resultant OFETs varied from 2.79 to 0.71, showing the conversion from n-type dominant to p-type dominant transport. With the same mole percentage of the TBAI to SeI polymer, a dramatic increment of μe/μh from 4.9 to 264 was observed, demonstrating the significant conversion from n-type dominant ambipolar to unipolar n-type transport. Overall, this study demonstrates the possibility of directional tunability of carrier polarity in organic ambipolar transistors with DPP- and BTI-based dual-acceptor polymers through molecular modification and the ionic additive strategy, being significantly beneficial for complementary circuits.

Write‐once‐read‐many (WORM) memory behavior is often observed in polymer electret memory (PEM) devices, greatly limiting their overall performance. This paper systematically investigates the device physics of PEM devices with poly(α‐methylstyrene) as a charge trapping layer and pentacene as a semiconductor channel. The combined experiments on transistors, capacitances, and optical spectroscopy reveal that both the WORM memory behavior after negative and positive pulses and the gradual formation of memory after the continuous scanning are the results of the deficiency in minority (electrons) transport and trapping. Corresponding quantitative models are established and well explain the two‐stage, gradual trapping processes to form memory. By reducing the structural disorder and lateral channel length, ambipolar, bistable memory and much faster formation of memory window is obtained based on the same PEM device. The insights into device physics of PEM devices are expected to facilitate the design of organic, nonvolatile memory devices with high programming and erasing efficiencies.

The ferroelectric properties of 20 nm Hf0.5Zr0.5O2 (HZO) thin films has been investigated in a wide temperature range from 100 K to 450 K. The remnant polarization of HZO thin films decreases slightly from 24.6 μC cm−2 (100 K) to 17.9 μC cm−2 (450 K), indicating a robust temperature stability. The capacitors also exhibit excellent endurance properties up to 109 cycles at 100 K and 300 K, and their endurance cycles slightly degrades to 108 at an elevated temperature of 450 K. The results show that HZO ferroelectric thin films have great potential for future emerging memory applications in various harsh temperature environments.

Three-terminal synaptic transistor has drawn significant research interests for neuromorphic computation due to its advantage of facile device integrability. Lately, bulk-heterojunction-based synaptic transistors with bipolar modulation are proposed to exempt the use of an additional floating gate. However, the actual correlation between the channel's ambipolarity, memory characteristic, and synaptic behavior for a floating-gate free transistor has not been investigated yet. Herein, by studying five diketopyrrolopyrrole-benzotriazole dual-acceptor random conjugated polymers, a clear correlation among the hole/electron ratio, the memory retention characteristic, and the synaptic behavior for the polymer channel layer in a floating-gate free transistor is described. It reveals that the polymers with balanced ambipolarity possess better charge trapping capabilities and larger memory windows; however, the high ambipolarity results in higher volatility of the memory characteristics, namely poor memory retention capability. In contrast, the polymer with a reduced ambipolarity possesses an enhanced memory retention capability despite showing a reduced memory window. It is further manifested that this enhanced charge retention capability enables the device to present artificial synaptic characteristics. The results highlight the importance of the channel's ambipolarity of floating-gate free transistors on the resultant volatile memory characteristics and synaptic behaviors.

A clear technical demonstration of the critical role of the blocking layers, which has never been addressed sufficiently in previous work.

In this study, we design and synthesize three DPP-based dual-acceptor conjugated polymers comprising different proquinoidal heterocyclic acceptors, including benzobisthiadizole (SS), triazolobenzothiadiazole (NS), and benzobistriazole (NN), and investigate their structure-property relationship...