Repeated Bending Cycles Research Articles

Predictive modeling for coiled tubing fatigue using advanced machine learning techniques

Coiled tubing CT plays Pivotal role in oil and gas well intervention operations due to its advantages such as flexibility, fast mobilization, safe, low cost and wide range of applications, including: well intervention, cleaning, stimulation, fluid displacement, cementing, and drilling. However, CT is subject of fatigue and mechanical damage caused by repeated bending cycles, internal pressure and environmental factors which can lead to a premature failure, high operational cost and production downtime. With the development of CT proprieties and application traditional fatigue life prediction methods based on analytical models integrated in tracking process showed in some cases an underestimate or overestimate of the actual fatigue life of CT particularly when complex factor like welding type, corrosive environment, and high-pressure variation are involved. This study addresses this limitation by introducing a comprehensive machine learning-based approach to improve the accuracy of CT fatigue life prediction, using a data set derived from over 350 tests both lab scale and full-scale fatigue test. The study has incorporated the impact of different parameters such as CT, grades, wall, thickness, CT diameter, internal pressure and welding types. By using advanced machine learning techniques such as artificial network (ANN), Gradient boosting regressor we got a more precise estimation of the number of cycles to failure than traditional models. The results of this study shown the importance of integration of machine learning for CT fatigue life analysis and demonstrating its capacity to enhance the prediction accuracy and reduce the uncertainty. A detailed machine Learning models is presented, emphasizing their capability to handle complex data and improve prediction under diverse operational conditions. This study contributes to more reliable, CT management and safer more cost-efficient well intervention operations.

Self‐Healing Waterborne Polyurethanes as a Sustainable Gel Electrolyte for Flexible Electrochromic Devices

Self‐healing polymers are promising for diverse applications in wearable technology and electronic skin. Polyurethanes are versatile polymers that can incorporate various monomer structures. Waterborne polyurethanes (WPUs) emerge as an environmentally conscious choice due to water usage instead of organic solvents, thereby minimizing the generation of volatile organic compounds. This study introduces a novel approach to enhance the self‐healing properties of WPUs by integrating disulfide bonds. These dynamic disulfide bonds undergo exchange reactions upon heating, facilitating the renewal of cross‐links on damaged film surfaces. Self‐healing WPUs with a low glass transition temperature achieve excellent self‐healing efficiency under mild conditions. Self‐healing adhesives applied to various flexible substrates retain stable peel strength, which confirms their potential as self‐healing solutions. Furthermore, the WPU hydrogel electrolyte is prepared with dihydroxyhexyl viologen (DHHV), and the prepared electrochromic gel exhibits good ionic conductivity while maintaining high transparency. The flexible electrochromic device exhibited excellent performances, including low coloration voltage, high coloration efficiency, and long‐term stability. The transmittance difference is exceptional, with over 99%, and no decay after repeated bending cycles is observed. The current results demonstrate the feasibility of self‐healing WPUs in improving the operation and durability of high‐performance flexible electrochromic devices.

One-Step Synthesis of Graphene-Covered Silver Nanowires with Enhanced Stability for Heating and Strain Sensing.

Solution-processed silver nanowire (AgNW) networks have been considered as promising electrode candidates for next-generation electronic devices. However, they suffer from poor thermal and electrical stability and low mechanical properties, hindering their practical applications. In this work, graphene nanosheets are successfully introduced into AgNW via a facile one-step solvothermal process. Benefiting from increased conductive paths, the resultant AgNW/graphene films exhibit high electrical conductivity. More importantly, the interlocking NW morphology can be maintained under high temperature and applied voltage due to suppressed Ag migration, which is enabled by the introduction of graphene. This feature leads to enhanced thermal and electrical stability, making them suitable for use as transparent heaters. Furthermore, the composite films present excellent mechanical performance, and negligible resistance change is observed after 10 000 repeated bending cycles. To demonstrate their feasibility toward sensor applications, sandwiched strain sensors are designed, which can endure larger tensile strains and show higher sensitivity and repeatability compared with pure AgNW-based device. Furthermore, various hand gestures can be easily recognized by the resultant sensors based on unique combinations of sensing response. This work not only provides a low-cost method to realize large-scale synthesis of AgNW/graphene composites but also offers guidance to prepare high-performance electrodes for advanced electronics.

Flexible and Disposable Hafnium Nitride Extended Gates Fabricated by Low-Temperature High-Power Impulse Magnetron Sputtering.

To obtain a high-performance extended gate field-effect transistor for pH detection, hafnium nitride (HfN) was first fabricated on an indium tin oxide on polyethylene terephthalate (ITO/PET) substrate using a high-power impulse magnetron sputter system (HiPIMS) in this study. It can be easily applied in biomedical diagnostic and environmental monitoring applications with the advantages of flexible, disposable, cost-effective, and reliable components. Various duty cycle conditions in HiPIMSs were designed to investigate the corresponding sensing performance and material properties including surface morphology and composition. As the duty cycle increased, the grain size of HfN increased. Additionally, X-ray photoelectron spectroscopy (XPS) analysis illustrated the presence of HfOxNy on the deposited HfN surface. Both behaviors could result in a better pH sensing performance based on the theory of the site-binding model. Subsequently, HfN with a 15% duty cycle exhibited excellent pH sensitivity and linearity, with values of 59.3 mV/pH and 99.8%, respectively; its hysteresis width and drift coefficient were -1 mV and 0.5 mV/h, respectively. Furthermore, this pH-sensing performance remained stable even after 2000 repeated bending cycles. These results indicate the potential and feasibility of this HiPIMS-deposited HfN for future wearable chemical applications.

Wireless Flexible System for Highly Sensitive Ammonia Detection Based on Polyaniline/Carbon Nanotubes.

Ammonia (NH3) is a harmful atmospheric pollutant and an important indicator of environment, health, and food safety conditions. Wearable devices with flexible gas sensors offer convenient real-time NH3 monitoring capabilities. A flexible ammonia gas sensing system to support the internet of things (IoT) is proposed. The flexible gas sensor in this system utilizes polyaniline (PANI) with multiwall carbon nanotubes (MWCNTs) decoration as a sensitive material, coated on a silver interdigital electrode on a polyethylene terephthalate (PET) substrate. Gas sensors are combined with other electronic components to form a flexible electronic system. The IoT functionality of the system comes from a microcontroller with Wi-Fi capability. The flexible gas sensor demonstrates commendable sensitivity, selectivity, humidity resistance, and long lifespan. The experimental data procured from the sensor reveal a remarkably low detection threshold of 0.3 ppm, aligning well with the required specifications for monitoring ammonia concentrations in exhaled breath gas, which typically range from 0.425 to 1.8 ppm. Furthermore, the sensor demonstrates a negligible reaction to the presence of interfering gases, such as ethanol, acetone, and methanol, thereby ensuring high selectivity for ammonia detection. In addition to these attributes, the sensor maintains consistent stability across a range of environmental conditions, including varying humidity levels, repeated bending cycles, and diverse angles of orientation. A portable, stable, and effective flexible IoT system solution for real-time ammonia sensing is demonstrated by collecting data at the edge end, processing the data in the cloud, and displaying the data at the user end.

Flexible Complementary Metal‐Oxide‐Semiconductor Inverter Based on 2D p‐type WSe2and n‐type MoS2

Transition metal dichalcogenides (TMDCs) are a promising class of two‐dimensional (2D) materials for flexible electronic applications due to their low integration temperature, good electronic properties, and excellent mechanical flexibility. Moreover, TMDCs offer the possibility of co‐integrating both n‐ and p‐type transistors on the same substrate, enabling the realization of complementary metal‐oxide‐semiconductor (CMOS) circuits. In this study, n‐type MoS2field‐effect transistors (FETs), and p‐type WSe2‐FETs integrated on a flexible foil substrate fabricated by standard thin‐film technology are presented. These devices exhibit high stability in their electronic operation under strain and repeated bending cycles. A CMOS inverter based on these transistors is also successfully demonstrated, which shows excellent switching behaviour with high gain (up to 100), high noise margin (0.87 · VDD), and low average static power consumption (40 pW).

Visible to near-infrared broadband electrochromic switching of π-extended viologen exhibiting highly efficient photothermal conversion

This study describes a new π-extended viologen molecule (TFBV) characterized by an electron-deficient structure inserted between two pyridinium groups. The single-layered electrochromic devices (ECDs) using TFBV all-in-one ion gel exhibit remarkable transparency under neutral conditions and display strong absorption bands in the visible and near-infrared (NIR) regions. The TFBV ECDs undergo a black coloration at a low operating voltage (−1.4 V), and at higher voltages (>−1.5 V), they display notable absorption in the NIR-II region. The two-electron reduction to neutral TFBV was confirmed through the chemical reduction of TFBV using Na2S, monitored through UV–vis spectra and 1H NMR titrations. The TFBV ECDs demonstrate an impressive color contrast of up to 96 % and a coloration efficiency of 150.18 cm2/C. The ECDs show outstanding kinetic stability through the 2000th cycle and moderate switching stability up to the 10000th cycle, accompanied by fast coloration times. Flexible TFBV ECDs, built on ITO PET, sustain superior performance even during flat and semicircle bending maneuvers, ensuring stability across repeated bending cycles. A uniform color transition is achieved in large-area ECDs of 10 cm × 10 cm. The strong NIR absorption of TFBV ECDs enables the photothermal heater to harvest the heat from the light energy, inducing a temperature rise of 45 °C. Furthermore, these devices perform a photothermal conversion efficiency of 52.5 % during multiple on–off cycles. TFBV ECDs, offering high transparency and intense darkness while blocking UV–Vis-NIR spectra, prove promising candidates for broadband ECDs with integrated photothermal conversion capabilities.

Liquid Metal‐Based Perovskite Solar Cells: In Situ Formed Gallium Oxide Interlayer Improves Stability and Efficiency

AbstractIn this study, eutectic gallium–indium alloy (EGaIn) liquid metal is used as the rear electrode for perovskite solar cells (PSCs), where the interfacial properties of the device, particularly the beneficial roles of the surface oxide of the liquid metal, are explored. The findings demonstrate that the native oxide of the EGaIn electrode significantly affects the stability of photovoltaic performance and impedance characteristics including series and shunt resistances. Based on the results, the following hypothesis is formulated: the oxide interlayer serves two crucial functions of a barrier against metal diffusion and a tunnel for enhancing charge extraction and transfer. The results of elemental mapping and trap density calculation support the former function of the hypothesis that the oxide film can effectively prevent metal penetration into the perovskite layer. Furthermore, measurements involving capacitance−voltage and time‐resolved photoluminescence confirm that the oxide film on the liquid metal eliminates the interfacial Schottky barrier, promoting efficient charge extraction and transfer processes. Finally, the investigation is extended to develop flexible PSCs using the EGaIn electrode, which consistently exhibits stable performance during repeated bending cycles. Notably, the EGaIn rear electrode can be readily removed and collected through a straightforward acid treatment, offering a promising avenue for efficient cell recycling.

Tissue Equivalent Curved Organic X-ray Detectors Utilizing High Atomic Number Polythiophene Analogues.

Organic semiconductors are a promising material candidate for X-ray detection. However, the low atomic number (Z) of organic semiconductors leads to poor X-ray absorption thus restricting their performance. Herein, the authors propose a new strategy for achieving high-sensitivity performance for X-ray detectors based on organic semiconductors modified with high -Z heteroatoms. X-ray detectors are fabricated with p-type organic semiconductors containing selenium heteroatoms (poly(3-hexyl)selenophene (P3HSe)) in blends with an n-type fullerene derivative ([6,6]-Phenyl C71 butyric acid methyl ester (PC70 BM). When characterized under 70, 100, 150, and 220kVp X-ray radiation, these heteroatom-containing detectors displayed a superior performance in terms of sensitivity up to 600 ± 11nCGy-1 cm-2 with respect to the bismuth oxide (Bi2 O3 ) nanoparticle (NP) sensitized organic detectors. Despite the lower Z of selenium compared to the NPs typically used, the authors identify a more efficient generation of electron-hole pairs, better charge transfer, and charge transport characteristics in heteroatom-incorporated detectors that result in this breakthrough detector performance. The authors also demonstrate flexible X-ray detectors that can be curved to a radius as low as 2mm with low deviation in X-ray response under 100 repeated bending cycles while maintaining an industry-standard ultra-low dark current of 0.03 ± 0.01pAmm-2 .

Mechanically strong, flexible, and flame-retardant Ti3C2Tx MXene-coated aramid paper with superior electromagnetic interference shielding and electrical heating performance

Undesirable electromagnetic interference (EMI) created by modern electronic devices has detrimental effects on the performance of high-precision electronic devices, information security, and human health. Therefore, lightweight, flexible, robust, and easy-to-fabricate EMI shielding materials with integrated functions are highly desirable to combat electromagnetic pollution. Herein, we report a scalable and facile strategy to prepare a flexible Ti3C2Tx MXene-coated aramid paper (MAP) with high-efficiency EMI shielding and excellent electrical heating performance. The intertwined network by aramid fibers endows the aramid paper (AP) with superior mechanical properties. After selectively single/dual coating with MXene onto AP, the MAP maintains a superior tensile strength of 73.6 MPa and enormous folding endurance of 4156 times. Owing to the exceptional electrical conductivity of MXene, the MAP with a relatively low MXene content (∼9.0 wt%) exhibits excellent overall performance with an EMI shielding effectiveness (SE) of 38 dB and SE/t of 422.2 dB mm−1. It’s noteworthy that the EMI SE of the MAP remains almost unchanged (37.4 dB) even after experiencing 5,000 repeated bending cycles. Additionally, the MAP shows satisfactory Joule electric-heating capability (a heating temperature rise of 130 °C at a low driving voltage of 5 V) and excellent flame-retardancy. This work provides a feasible strategy for large-scale production of flexible EMI shielding paper with multifunctional properties for future wearable facilities.

Thermoelectric Properties of One-Pot Hydrothermally Synthesized Solution-Processable PEDOT:PSS/MWCNT Composite Materials.

The combination of organic and inorganic materials has been considered an effective solution for achieving ambient thermoelectric energy harvesting and has been developing rapidly. Here, PEDOT:PSS/MWCNT (PPM) composite hydrogels were synthesized using the self-assembled gelation process of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and the interaction between PEDOT:PSS and multi-walled carbon nanotubes (MWCNTs) without the addition of any surfactant. After immersion in dimethyl sulfoxide and freeze-drying, the hydrogel is easily dispersed in water and used as a direct ink writing (DIW) 3D printing ink. At room temperature, the PPM-20 printed film with 20 wt% MWCNT solids achieved a maximum power factor of 7.37 μW m-1 K-2 and maintained stable thermoelectric properties during repeated bending cycles. On this basis, a thermoelectric generator (TEG) consisting of five legs was printed, which could be produced to generate an open circuit voltage of 6.4 mV and a maximum output power of 40.48 nW at a temperature gradient of 50 K, confirming its great potential for application in high-performance flexible organic/inorganic thermoelectric materials.

Multifunctional MoSe2 @MXene Heterostructure-Decorated Cellulose Fabric for Wearable Thermal Therapy.

A booming demand for wearable electronic devices urges the development of multifunctional smart fabrics. However, it is still facing a challenge to fabricate multifunctional smart fabrics with satisfactory mechanical property, excellent Joule heating performance, highly efficient photothermal conversion, outstanding electromagnetic shielding effectiveness, and superior anti-bacterial capability. Here, a MoSe2 @MXene heterostructure-based multifunctional cellulose fabric is fabricated by depositing MXene nanosheets onto cellulose fabric followed by a facile hydrothermal method to grow MoSe2 nanoflakes on MXene layers. A low-voltage Joule heating therapy platform with rapid Joule heating response (up to 230°C in 25 s at a supplied voltage of 4V) and stable performance under repeated bending cycles (up to 1000cycles) is realized. Besides, the multifunctional fabric also exhibits excellent photothermal performance (up to 130°C upon irradiation for 25 s with a light intensity of 400mW cm-2 ), outstanding electromagnetic interference shielding effectiveness (37dB), and excellent antibacterial performances (>90% anti-bacterial rate toward Escherichia coli, Bacillus subtilis, and Staphylococcus aureus). This work offers an efficient avenue to fabricate multifunctional wearable thermal therapy devices for mobile healthcare and personal thermal management.

Conducting Polymer Hydrogel Driven By Sodium Chloride as High Performance Flexible Supercapacitor Electrode

With the rapid development of the wearable devices and flexible supercapacitors (FSCs), urgent demand for electrodes with high specific capacitance and excellent flexibility have been put forward. Herein, a self-standing conducting polymer hydrogel electrode has been successfully synthesized by in situ polymerization of aniline (ANI) in aqueous solution of polyvinyl alcohol (PVA), phytic acid (PA) and sodium chloride (NaCl). The prepared PANI/PVA/NaCl (PPN) hydrogel electrode shows high specific capacitance (1544 mF cm−2 at current density of 1 mA cm−2), good flexibility (elongation at fracture of 110%), satisfactory electrochemical stability (92% capacitance retention after 500 repeated bending cycles) and excellent cycling stability (78.2% capacitance retention after 10000 cycles) due to the uniform 3D interconnected structure driven by NaCl pseudo template. In order to further explore the potential application prospects of the synthesized hydrogel in flexible devices, a series of all-hydrogel-state FSCs are assembled based on the prepared PPN hydrogel electrodes and typical PVA/H2SO4 electrolyte. The assembled FSCs exhibit high energy density of 51.1 μWh cm−2 at power density of 250 μW cm−2 and long-life stability of 81.10% capacitance retention after 10000 charge/discharge cycles. This work provides a new synthesis strategy for the high performance energy storage electrodes and devices.

High-Performance Flexible Transparent Electrical Heater Based on a Robust Ordered Ag Nanowire Micromesh Conductor

High-performance electrical heaters with a rapid thermal response, homogeneous temperature distribution, and chemical and mechanical robustness are desirable for inevitable use in various areas such as defrosting windows and wearable thermotherapy. Herein, optimally engineered ordered Ag nanowire micromeshes are partially embedded in poly(ethylene terephthalate) matrix (Ag NMs/ePET) via a facile spray coating and transfer approach for flexible transparent conductor and electrical heater applications, which exhibit a slight sheet resistance variation of less than 5%. The resultant Ag NMs/ePET heater exhibits uniform heat distribution over the entire film and can achieve a saturation temperature of 134 °C with a rapid response time of 5 s under an input voltage of 6 V. In addition, owing to the large-diameter nanowire micromesh structure and the protective effect of PET encapsulation, the flexible transparent Ag NMs/ePET heater presents excellent mechanical and chemical robustness in extreme environments and still maintains a stable heating performance after 5000 repeated bending cycles (r = 5 mm) and exposure to a corrosive solution. This work lays the foundation for improving the electrical heater performance and provides a facile methodology to fabricate a high-performance flexible transparent conducting film for other innovative applications.

Flexible perovskite nanosheet-based photodetectors for ultraviolet communication applications

Ultraviolet (UV) photodetection has attracted much attention for applications like monitoring ozone holes and light communication. Although UV photodetectors based on conventional inorganic semiconductors have been widely investigated, fast response devices with high sensitivity remain needed for UV communication systems. This Letter reports on flexible ultrathin methylammonium lead bromide(MAPbBr3)-based UV photodetectors. In the UV regime, the response time reaches 3.3/4.0 μs, and the 3 dB bandwidth is 0.22 MHz. No current degradation is detected after repeated bending cycles, indicating the excellent mechanical flexibility and reliability of flexible high-speed UV photodetectors. Moreover, MAPbBr3 nanosheet-based photodetectors have been integrated into a UV communication system as signal receivers transmitting messages encrypted by international Morse codes. These results reveal the potential of ultrathin perovskite nanosheets in developing flexible optoelectronic devices for UV communications and related applications.

Molecular Weight Tuning of Organic Semiconductors for Curved Organic-Inorganic Hybrid X-Ray Detectors.

Curved X‐ray detectors have the potential to revolutionize diverse sectors due to benefits such as reduced image distortion and vignetting compared to their planar counterparts. While the use of inorganic semiconductors for curved detectors are restricted by their brittle nature, organic–inorganic hybrid semiconductors which incorporated bismuth oxide nanoparticles in an organic bulk heterojunction consisting of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) and [6,6]‐phenyl C71 butyric acid methyl ester (PC70BM) are considered to be more promising in this regard. However, the influence of the P3HT molecular weight on the mechanical stability of curved, thick X‐ray detectors remains less well understood. Herein, high P3HT molecular weights (>40 kDa) are identified to allow increased intermolecular bonding and chain entanglements, resulting in X‐ray detectors that can be curved to a radius as low as 1.3 mm with low deviation in X‐ray response under 100 repeated bending cycles while maintaining an industry‐standard dark current of <1 pA mm−2 and a sensitivity of ≈ 0.17 μC Gy−1 cm−2. This study identifies a crucial missing link in the development of curved detectors, namely the importance of the molecular weight of the polymer semiconductors used.

Mechanical Durability of Flexible/Stretchable a-IGZO TFTs on PI Island for Wearable Electronic Application

In this work, we examined the mechanical durability of island-type a-IGZO thin-film transistors (TFTs). Island TFTs were fabricated on polyimide (PI) islands and were transferred to a thermoplastic polyurethane (TPU) film. In repeated bending tests with a 1.5 mm bending radius, island TFTs showed less electrical property deterioration than TFTs on a PI film. We confirmed that the TPU, which has a lower elastic modulus compared to PI, effectively reduced the curvature of PI island even under the same bending test conditions. Furthermore, an organic passivation layer was applied on the upper part of the PI island. The 3 μm thick organic passivation layer made the TFT layer more stable against bending and elongation stress. Island TFTs with an organic passivation layer showed a change in the saturation mobility of only −2.3% and a change in the threshold voltage of −0.22 V even after 250 000 repetitive bending tests. Additionally, no change in electrical properties was observed even after 10 000 repeated stretching test cycles under 30% uniaxial elongation. Finally, we fabricated island-type logic circuits based on a-IGZO TFTs for wearable electronic applications. Using the organic passivation layer, we showed that the NMOS pseudoinverter and NAND gate also operated without significant deterioration in 100 000 repeated bending cycles and 5000 repeated stretching cycles. After applying repeated mechanical stresses, the high output voltage (VOH) and low output voltage (VOL) of the inverter only changed from 8.85 to 8.93 V and from 0.44 to 0.50 V, respectively. In NAND gates, VOH and VOL only changed slightly from 8.46 to 8.56 V and from 0.45 to 0.55 V, respectively.

Flexibility of Room-Temperature-Synthesized Amorphous CdO-In2O3 Alloy Films and Their Application as Transparent Conductors in Solar Cells.

Due to their low-temperature deposition, high mobility (>10 cm2/V·s), and electrical conductivity, amorphous ionic oxide semiconductors (AIOSs) have received much attention for their applications in flexible and/or organic electro-optical devices. Here, we report on a study of the flexibility of CdO-In2O3 alloy thin films, deposited on a polyethylene terephthalate (PET) substrate by radio frequency magnetron sputtering at room temperature. Cd1-xInxO1+δ alloys with the composition of x > 0.6 are amorphous, exhibiting a high electron mobility of 40-50 cm2/V·s, a low resistivity of ∼3 × 10-4 Ω·cm, and high transmittance over a wide spectral window of 350 to >1600 nm. The flexibility of both crystalline and amorphous Cd1-xInxO1+δ films on the PET substrate was investigated by measuring their electrical resistivity after both compressive and tensile bending with a range of bending radii and repeated bending cycles. Under both compressive and tensile bending with Rb = 16.5 mm, no significant degradation was observed for both the crystalline and amorphous films up to 300 bending cycles. For a smaller bending radius, the amorphous film shows much less electrical degradation than the crystalline films under compressive bending due to less film delamination at the bending sites. On the other hand, for a small bending radius (<16 mm), both crystalline and amorphous films degrade after repeated tensile bending, most likely due to the development of microcracks in the films. To demonstrate the application of amorphous Cd1-xInxO1+δ alloy in photovoltaics, we fabricated perovskite and bulk-heterojunction organic solar cells (OSCs) on glass and flexible PET utilizing amorphous Cd1-xInxO1+δ layers as transparent electrodes. The organic-inorganic hybrid perovskite solar cells (PSCs) exhibit a power conversion efficiency (PCE) of ∼11 to 12% under both front and back illumination, demonstrating good bifacial performance with bifaciality factor >90%. The OSCs fabricated on an amorphous Cd1-xInxO1+δ-coated flexible PET substrate achieve a promising PCE of 12.06%. Our results strongly suggest the technological potentials of amorphous Cd1-xInxO1+δ as a reliable and effective transparent conducting material for flexible and organic optoelectronic devices.

Electrical characteristics of flexible amorphous indium–tin–gallium–zinc oxide thin-film transistors under repetitive mechanical stress

In this study, we investigated the effect of repetitive mechanical stress on the electrical characteristics of amorphous indium–tin–gallium–zinc oxide (a-ITGZO) thin-film transistors (TFTs). The degradation of the electrical characteristics of an a-ITGZO TFT with a curvature radius of 2 mm is minimal even after the TFT undergoes bending 105 times. Our technology computer-aided design simulation reveals that the electrical characteristics degraded by the repeated bending cycles are due to the increase in the acceptor-like Gaussian states (N GA) related with the generation of oxygen interstitial defects.

Regulating the Self-Discharge of Flexible All-Solid-State Supercapacitors by a Heterogeneous Polymer Electrolyte.

Supercapacitors with high power density and an ultralong cyclic lifetime have been intensively investigated. However, the crucial challenge of their rapid self-discharge process is often neglected in most cases. A heterogeneous interface formed between two layers of polymer electrolytes is designed, in which a polyanion and a polycation are added into a common matrix of polymer electrolyte, respectively. By using the heterogeneous polymer electrolyte (HPE) as the separator simultaneously, the resultant supercapacitors exhibit comparable electrochemical performance to that of devices based on traditional polymer electrolytes. The HPE-based supercapacitors using both electric double-layer capacitive and pseudocapacitive electrodes show at least one time longer self-discharge time than that of devices based on homogenous polymer electrolyte, especially for the electrode in an electrolyte containing polyanion served as a positive pole during the charging process. Because of the same polymer matrix used, the heterojunction structure of the HPE exhibits excellent stability without obvious phase separation during thousands of charge/discharge and repeated bending cycles. This novel strategy by interface engineering of electrolyte to suppress the self-discharge behavior of supercapacitors is very meaningful to promote their practical applications.