Stable Switching Research Articles

Study of current conduction mechanism and resistive switching stability in the PVdF-HFP-based memristor

Study of current conduction mechanism and resistive switching stability in the PVdF-HFP-based memristor

Modulating the resistive switching stability of HfO2-based RRAM through Gd doping engineering: DFT+U.

Oxide-based resistive random access memory (RRAM) is standing out in both non-volatile memory and the emerging field of neuromorphic computing, with the consequence of increasing performance demands. Rare-earth doping is often used as an effective means for performance modulation. In this work, the modulation mechanism of the resistive switching (RS) behaviors in trivalent rare-earth Gd-doped HfO2-based RRAM has been carefully investigated using first-principles calculations. The results of electronic structure analysis show that Gd doping would lead to a change in the local geometry of the m-HfO2 defect system and would enhance the Coulomb interaction between the atoms around Gd and oxygen vacancy (VO), which may be one of the reasons for the enhanced conductivity of the HfO2-based RRAM after Gd doping. Thermodynamic and kinetic study results indicate that there is a strong interaction between Gd and its surrounding VO defects, and this strong interaction would not only attract more oxygen vacancies (VOs) to be generated near the dopant Gd, but also increase the migration energy barrier of the +2 charged VOs around the Gd doping site, thus suppressing the random generation of VO filaments, which leads to a better uniformity of the switching parameters during the RS process and improves the performance stability of the devices. The results of this work will provide new insights into modulating the RS behaviors and improving the device performance of HfO2-based RRAM through doping engineering.

Light-switchable emulsions: From reversible emulsification-demulsification to controllable microreactors

The long-term stability of emulsions and reversible switching of emulsification- demulsification are important scientific issues in the field of emulsions. However, the reversible modulation of the phase behavior of emulsions without additives by light irradiation is still a challenge. Here, a novel class of light-responsive emulsions with controllable phase behavior was designed and prepared. It was found that the stable emulsions formed by alkane-, water- and azobenzene-based ionic liquid surfactants could be reversibly switched between demulsification and re-emulsification by alternating UV and visible light irradiation under stirring. Mechanistic results showed that a decrease in the surface activity of the azobenzene-based ionic liquid surfactants caused by photoisomerization under UV irradiation is the main factor resulting in the demulsification of stable emulsions. Based on the investigation of the light-switchable phase behavior of the emulsions, such systems were designed as controllable microreactors for efficient Knoevenagel reactions under mild conditions with simple separation and recycling characteristics. The strategy developed here opens a new pathway for the development of sustainable chemical processes.

Resistive switching behaviors of cobalt oxide films with structural change by post-thermal annealing

We have studied the resistive switching behaviors of cobalt oxide films with structural changes by a post-thermal annealing process. During post-annealing at temperatures of 500–700 °C for the CoOx films deposited by ultra-high-vacuum RF magnetron sputtering, two structural phases of CoO and Co3O4 were modulated by selection of ambient N2 or O2 gases. As a device application of these films, the resistive random-access memory (ReRAM) structures of p+-Si/CoOx/Ti/Au were fabricated with CoO or Co3O4 films by post-annealing at 700 °C under N2 and O2 atmosphere, respectively. The resistive switching characteristics of the CoO device appeared much better than that of the Co3O4 device, also showing good uniformity from a cumulative probability distribution, long non-volatile retention characteristics of 104 s, good endurance of ∼100 cycles, and an excellent current ratio of 104. These results demonstrate the method to provide stable and good resistive switching properties of sputtered CoO films using the phase selection during post-thermal annealing.

Multifunctional Ag–In–Zn–S/Cs3Cu2Cl5‐Based Memristors with Coexistence of Non‐Volatile Memory and Volatile Threshold Switching Behaviors for Neuroinspired Computing

AbstractLead‐free all‐inorganic Cs3Cu2Cl5 perovskites, a member of the metal‐metal halide material family, have attracted pronounced attention owing to their low toxicity, facile fabrication strategies, considerable ambient stability, and intriguing photoelectric properties. However, the application of environmentally friendly copper‐based Cs3Cu2Cl5 in memristors has been rarely reported to the authors’ knowledge. Herein, multifunctional memristors with the coexistence of non‐volatile memory (MS) and volatile threshold switching (TS) behaviors are introduced based on an innovative Ag–In–Zn–S/Cs3Cu2Cl5 heterostructure. The inserted Ag–In–Zn–S quantum dots layer may provide an effective method for guiding the formation of the dominant metallic Ag filaments, resulting in considerably stable and controllable multiple switching behaviors. Additionally, the heterostructure memristor is capable of imitating some essential biological synaptic functions, including long‐term potentiation (LTP), long‐term depression (LTD), and the short‐term memory (STM) to long‐term memory (LTM) transition. Furthermore, the famous conditioning Pavlov's dog experiment corresponding to associative learning is electronically simulated by the studied device. Moreover, utilizing the devices’ LTP and LTD properties, relatively high recognition accuracies for small and large digits datasets are achieved through a three‐layer artificial neural network, revealing the feasibility of implementing neuromorphic computation using heterostructure memristors.

Histidine network regulates the structure-stability features of T7 endolysin native and partially folded conformations

Conformational transitions displayed by proteins are a classical phenomenon associated with the structural intricacies that directly influence concomitant functionality. pH-dependent conformational switching is the combined outcome of pKa and pH that regulate the network of crucial interactions via side chain protonation-deprotonation, thus governing the structure-stability-activity of proteins. Histidine is a unique amino acid owing to its aromatic and ionizable imidazole side chain, which enables it to act as a hydrogen bond donor and acceptor under differential pH conditions/protonation events. The peptidoglycan degrading enzyme T7 endolysin possesses a conserved quad-His (H18, H48, H69, and H123) network at its hydrophobic core regulating the pH-induced conformational transition. However, the degree of involvement of individual His residue is currently unknown. In the current study, four T7L variants (H18K, H48K, H69K, and H123K) were designed, and the contribution of each site to T7L activity, conformational heterogeneity, reversibility, and stability of native/partially folded state has been assessed using a detailed biophysical, NMR, and cell-based analysis of amidase activity. The results delineated the prime responsibility of His48 followed by His69 and His18 in regulating the core structural stability, amidase activity, and pH-dependent conformational switching of T7L. The perturbations due to protonation of His network altered the associated polar and nonpolar interactions within the network and with the surrounding residues, thus essentially mediating the pH-dependent conformational transition of T7L. All the observed experimental evidence establishes the regulatory role of “histidine molecular switches” in the structure–activity paradigm of bacteriophage amidases.

Non-Volatile Memory and Synaptic Characteristics of TiN/CeOx/Pt RRAM Devices.

In this study, we investigate the synaptic characteristics and the non-volatile memory characteristics of TiN/CeOx/Pt RRAM devices for a neuromorphic system. The thickness and chemical properties of the CeOx are confirmed through TEM, EDS, and XPS analysis. A lot of oxygen vacancies (ions) in CeOx film enhance resistive switching. The stable bipolar resistive switching characteristics, endurance cycling (>100 cycles), and non-volatile properties in the retention test (>10,000 s) are assessed through DC sweep. The filamentary switching model and Schottky emission-based conduction model are presented for TiN/CeOx/Pt RRAM devices in the LRS and HRS. The compliance current (1~5 mA) and reset stop voltage (−1.3~−2.2 V) are used in the set and reset processes, respectively, to implement multi-level cell (MLC) in DC sweep mode. Based on neural activity, a neuromorphic system is performed by electrical stimulation. Accordingly, the pulse responses achieve longer endurance cycling (>10,000 cycles), MLC (potentiation and depression), spike-timing dependent plasticity (STDP), and excitatory postsynaptic current (EPSC) to mimic synapse using TiN/CeOx/Pt RRAM devices.

Individual differences in resilience to stress are associated with affective flexibility

Cognitive flexibility is frequently linked to resilience because of its important contribution to stress regulation. In this context, particularly affective flexibility, defined as the ability to flexibly attend and disengage from affective information, may play a significant role. In the present study, the relationship of cognitive and affective flexibility and resilience was examined in 100 healthy participants. Resilience was measured with three self-report questionnaires, two defining resilience as a personality trait and one focusing on resilience as an outcome in the sense of stress coping abilities. Cognitive and affective flexibility were assessed in two experimental task switching paradigms with non-affective and affective materials and tasks, respectively. The cognitive flexibility paradigm additionally included measures of cognitive stability and spontaneous switching in ambiguous situations. In the affective flexibility paradigm, we explicitly considered the affective valence of the stimuli. Response time switch costs in the affective flexibility paradigm were significantly correlated to all three measures of resilience. The correlation was not specific for particular valences of the stimuli before or during switching. For cognitive (non-affective) flexibility, a significant correlation of response time switch costs was found with only one resilience measure. A regression analysis including both affective and cognitive switch costs as predictors of resilience indicated that only affective, but not cognitive switch costs, explained unique variance components. Furthermore, the experimental measures of cognitive stability and the rate of spontaneous switching in ambiguous situations did not correlate with resilience scores. These findings suggest that specifically the efficiency of flexibly switching between affective and non-affective information is related to resilience.

Supramolecular Framework Constructed by Dendritic Nanopolymer for Stable Flexible Perovskite Resistive Random-Access Memory.

The 3D supramolecular framework (3D-SF) is constructed in this work through the hydrogen bond assisted self-assembly of spherical dendritic nanopolymer to regulate the flexibility, stability, and resistive switching (RS) performance of perovskite resistive random-access memory (RRAM). Herein, the 3D-SF network acts as the perovskite crystallization template to regulate the perovskite crystallization process due to its coordination interaction of functional groups with the perovskite grains, presenting the uniform, pinhole-free, and compact perovskite morphology for stable flexible RRAM. The 3D-SF network in situ stays at the perovskite intergranular boundaries to crosslink the perovskite grains. The RS performance of 3D-SF-modified perovskite RRAM device is evidently improved to the ON/OFF ratio of 105 , the cycle number of 500 times, and the data retention time of 104 s. The 50-days exposure of unencapsulated RRAM device at ambient environment still makes the ON/OFF ratio to be kept at ≈104 , indicating the potential of long-term stable multilevel storage in the high-density data storage. The bending action under different radius also does not change the RS performance due to the excellent bending-resistant ability of 3D-SF-modified perovskite film. This work explores a novel polymer additive strategy to construct the 3D supramolecular framework for stable flexible perovskite optoelectronic devices.

Vortex Domain Wall Thermal Stability in Magnetic Nanodevices with In‐Plane Magnetic Anisotropy

Thermal switching of vortex domain walls (VW) in planar magnetic nanowires is a key challenge for storing data. Understanding the VW magnetization thermal switching, thermal transformation, and dynamics in magnetic nanowires is essential for the development of magnetic data storage. Thus, a micromagnetic simulation is used to investigate the effect of device temperature (T) on VW thermal switching, structural transformation, and VW dynamics in magnetic nanowires. The VW thermal nucleation is examined based on magnetic properties and magnetization in nanowires becomes more stable. Furthermore, in this study, it is found that VW thermal structural stability decreases by increasing the device temperature. The speed of VW is observed to rise exponentially by increasing the device temperature up to 600 m s−1. Thus, the VW memory is fast in writing and reading stored data at room temperature and higher. The findings reveal the potentiality of a VW simple nanomagnetic as a building block for spintronic devices such as a memory cell where the bit data are stored and VW are stable with high thermal switching stability.

1279. Real World Treatment Experience of Treatment-Naïve People with HIV who Initiated Treatment with Single Tablet Dolutegravir/Lamivudine in a Test and Treat setting in the US.

Abstract Background Dolutegravir/lamivudine (DTG/3TC) is indicated as a 2DR for both treatment-naïve and virally suppressed PLWH. The feasibility of DTG/3TC use in a Test & Treat (T&T) setting has been demonstrated in a clinical trial, but there is limited evidence with this approach in US real world clinical settings. Methods TANDEM was a retrospective medical chart review conducted across 24 US sites. Eligible PLWH were adults initiated on DTG/3TC or DTG/rilpivirine (DTG/RPV) prior to Sept/30/2020 with a minimum clinical follow-up of six months. Treatment-naïve (TN) PLWH had no prior history of HIV therapy. Clinical characteristics, treatment history and outcomes were abstracted. Analyses were descriptive. Reported here are results for the sub-group of TN PLWH that were initiated DTG/3TC as part of a T&T strategy, defined as clinician attestation of treatment initiation shortly after diagnosis and in the absence of known lab values for HIV-1 RNA viral load, CD4 cell count and HIV-1 resistance mutations. Results From an overall sample of 469 PLWH on DTG-based 2DR, 318 received DTG/3TC, of whom, 126 were TN and 192 were stable switch. Almost half 48% of PLWH received DTG/3TC as part of a T&T paradigm. Characteristics of the cohort are described in Table 1. In the T&T sub-group, the most common reasons for initiating DTG/3TC were avoidance of long-term toxicities (n=26), followed by simplification/streamlining (n=8) and convenience (n=7). Overall, 114 (90.5%) of TN PLWH achieved the desired health outcome per clinician attestation. At data cut-off, 61 (94%) non T&T achieved virologic suppression, 57 (93%) of the T&T sub-group achieved virological suppression, 3 (5%) did not, and 1 (2%) was still unknown. Of the 3 who did not achieve suppression, 2 remained on DTG/3TC while 1 was switched to bictegravir/emtricitabine/tenofovir alafenamide. Virologic rebound occurred in 6 TN PLWH overall with only 1 occurring in the T&T sub-group. Baseline Characteristics and Virologic Outcomes Conclusion Reflecting results from clinical trials, DTG/3TC achieved its desired health outcomes in the majority of cases regardless of treatment paradigm, with virtually no difference in virological suppression rates across the two cohorts (93-94% achieving suppression in a median duration of 10-11 weeks). Disclosures Cindy Donovan, PharmD, Johnson & Johnson: Stocks/Bonds|ViiV Healthcare: Employee/Salary|ViiV Healthcare: Stocks/Bonds Gavin Harper, BA, ViiV Healthcare: Adelphi Real World were paid consultants (CRO) to conduct the observational research study on behalf of ViiV Healthcare.|ViiV Healthcare: Adelphi Real World were paid consultants (CRO) to conduct the observational research study on behalf of ViiV Healthcare Deanna Merrill, PharmD, MBA, AAHIVP, ViiV Healthcare: Salaried employee|ViiV Healthcare: Stocks/Bonds Katie L. Mycock, MChem, ViiV Healthcare: Adelphi Real World were paid consultants (CRO) to conduct the observational research study on behalf of ViiV Healthcare|ViiV Healthcare: Adelphi Real World were paid consultants (CRO) to conduct the observational research study on behalf of ViiV Healthcare Alan Oglesby, MPH, GlaxoSmithKline (GSK): Employment|GlaxoSmithKline (GSK): Stocks/Bonds Aimee Metzner, PharmD, AAHIVP, ViiV Healthcare: Salaried employee|ViiV Healthcare: Stocks/Bonds Jimena Patarroyo, PharmD, AAHIVP, ViiV Healthcare: Salaried employee|ViiV Healthcare: Stocks/Bonds|ViiV Healthcare: Stocks/Bonds.

Effect of a novel generalized incidence rate function in [formula omitted] model: Stability switches and bifurcations

When a disease outbreaks in a population, the incidence rate function may increase initially with an increase of infective and then decrease due to inhibitory effects before getting saturated. For this purpose, we propose a new generalized incidence rate function and demonstrate the impact of this incidence rate function’s non-monotonic feature on the stability of endemic equilibria. In this paper, an SIR compartmental model with this new nonlinear incidence rate function and saturated treatment rate function is proposed. We obtain a disease free equilibrium which is locally stable for R0<1 and unstable otherwise. The system may have multiple endemic equilibria which can be either anti-saddle (node, focus or center) or saddle. We discover that when the incidence rate function is increasing at an anti-saddle endemic equilibrium, the endemic equilibrium may become either stable, unstable or switch stability via a parameter change. However, when the incidence rate function is non-monotonic and if the incidence rate decreases at an anti-saddle endemic equilibrium, the endemic equilibrium is always stable. Due to the limited treatment, we find forward (transcritical) and backward bifurcations. We also establish Hopf bifurcation and saddle–node bifurcation in the model system. Further, we incorporate the incubation delay in the model system. We obtain the same number of equilibria in the delay model. The disease free equilibrium is locally asymptotically stable for all delay lengths for R0<1. The endemic equilibrium switches its stability due to change in delay. Due to delay variation, the increasing incidence rate at an anti-saddle endemic equilibrium causes the multiple stability switches of the equilibrium from both stable and unstable initial states. Further, when the incidence rate decreases at the stable anti-saddle endemic equilibrium, it switches its stability once or multiple times and finally becomes unstable due to delay variation. We explicitly, show multiple stability switches of an endemic equilibrium due to existence of multiple Hopf bifurcations. When we further analyzed model system numerically, we could establish the existence of Hopf–Hopf bifurcation of codimension 2. In this case, the increase in the delay parameter causes the existence of two oscillatory solutions around the unstable endemic equilibrium. Hence, our results show that the delay system either destabilize developing the same frequency oscillations via Hopf bifurcation or two different frequency oscillations via Hopf–Hopf bifurcation of codimension 2. The existence and exhibition of these two frequency oscillations are novel and have not been explored much in epidemiological models.

Theoretical Investigation of Origin of Quantized Conduction in 2D Layered Ruddleson–Popper Perovskite Heterostructure for the RRAM Applications

Quantized conduction achieved in layered materials offers a wide range of applications in electronics. A comprehensive analysis of electronic properties of Sr2ZrO4/TiN- and Sr2ZrO4/TaN-layered heterostructure is carried out using plane wave-based first principles calculations. To understand the origin of quantized conduction, the role of oxygen vacancies (Vos) in 2D layered Ruddleson–Popper perovskite (Sr2ZrO4) is analyzed using density of states, isosurface, and integrated charge density plots. The origin of quantized states formed near the Fermi level is proposed in terms of charge conduction layer formed at the interface. The comprehensive insight of Sr2ZrO4/TiN and Sr2ZrO4/TaN heterostructure interface is provided by shedding light on the charge redistribution from charge density and Bader charge analysis. Meanwhile, work function is calculated for the confirmation of charge conducting behavior of the two layered heterostructures. The interface of these two layered heterostructures revealed the quantized conduction phenomena which cannot be achieved with either layer alone. Stable switching achieved withaTaN electrode being an important task for robust RS and solving sneak path related problem is opening roadmap for 2D layered RRAM devices.

MoTe2-based low energy consumption artificial synapse for neuromorphic behavior and decimal arithmetic

Two-dimensional material-based memristors have shown attractive research prospects as brain-like devices for neuromorphic computing. Among them, transition metal dichalcogenides–based memristors have proved to be one of the most promising competitors. In this work, a two-dimensional memristor based on MoTe2 nanosheets was fabricated and demonstrated. The experimental results illustrate that the two-terminal synaptic based on the Ag/MoTe2/ITO structure exhibits stable bipolar and non-volatile resistive switching characteristics attributed to the controllable formation and rupturing of silver conductive filaments. The device can be successively modulated by a pulse train with a minimum pulse width of 40 ns. More interestingly, the energy consumption of the device to complete one write event is only 74.2 pJ. In addition, biological synaptic behaviors, such as excitatory postsynaptic current gain properties, long-term potentiation (LTP)/long-term depression, spike-timing-dependent- plasticity, short-term plasticity, long-term potentiation (LTP), paired-pulse facilitation, post-tetanic potentiation, and learning-experimental behaviors were mimicked faithfully. Finally, the decimal arithmetic application was introduced to the device, and it is confirmed that addition and multiplication functions can be performed. Therefore, the artificial synapse based on MoTe2 nanosheets not only exhibits the stable non-volatile resistive switching behavior but also facilitates the development of low-energy consumption neuromorphic computing chips based on transition metal dichalcogenides.

Multiple dynamics in a delayed predator‐prey model with asymmetric functional and numerical responses

We consider a predator‐prey model with dissimilar functional and numerical responses that induce an Allee effect. There is a time lag between consumption and digestion of prey biomass by predator. Hence, a time delay has been incorporated in the numerical response function. The system consists of two interior equilibria. Taking time delay as the bifurcation parameter, four different dynamic behaviors appear, viz., (R1) system undergoes no change in its stability for all time delay, (R2) system undergoes stability change, (R3) system undergoes stability switching, and (R4) system undergoes instability switching. Here, finding four distinct dynamics in a single population model with only one delay is a novelty in this contribution. This variation in dynamics emerges due to asymmetricity in functional and numerical responses. All the relevant theorems in establishing stability are provided, and these are verified numerically. We analytically prove that if an interior equilibrium is a saddle point in absence of time delay, then the equilibrium cannot be stabilized by varying the time delay. It is popularly believed that existence of two distinct pair of purely imaginary roots of the characteristic function leads to stability switching. However, we provide examples where the system remains unstable, stability changes, and instability switching occurs. This is another new and interesting observation in our work. The numerical examples are furnished with phase portraits, time series plots, bifurcation diagrams, and eigenvalues evaluation with delay, for better understanding. Our model with a single delay exhibits variety of dynamics, which were not explored before.

A memristor based on two-dimensional MoSe2/MoS2 heterojunction for synaptic device application

Two-dimensional materials are promising for exploring memristors with excellent performance. However, the memristor still faces challenges in insufficient reliability due to resistance-switching mechanisms of conductive filaments. In this work, a typical metal/heterojunction/metal structure (Ag/MoSe2/MoS2/Au/Ti) was proposed as the device architecture of the memristor. The device exhibits stable bipolar resistive switching behavior with a high on–off ratio, long retention time, and good endurance. The resistance-switching is achieved by adjusting the interface barrier of the MoSe2/MoS2 due to the band modulation. Moreover, we explore the essential synaptic functions of this memristor device, with outstanding voltage pulse potentiation and depression. Our work highlights the significant prospects of MoSe2/MoS2 heterojunction in artificial synapses and neural networks.

Annealing induced cation diffusion in TaOx-based memristor and its compatibility for back-end-of-line post-processing

The effect of annealing on the switching characteristics of memristor devices cannot be overlooked because the thermal process can exhibit both positive and negative effects on the performance of the devices. We investigated the switching behavior of TaOx-based memristors (electrochemical metallization cell type, ECM) that were Ar-ambient annealed under two conditions, with and without the active electrode. We found a high concentration of metal species in the TaOx films, even in the device where the TaOx was annealed without the active top electrode. This indicates that the properties of the annealed films encourage the diffusion of metal species in the oxide. We suggest that the increase in non-lattice oxygen (by 4.1%, indicating a higher concentration of Vo defects) after the annealing process plays a role in this phenomenon. In addition, the concentration of metal species that exist prior to the switching activation as well as the structure of the conducting bridge determines the switching stability of the devices. The device that annealed before top electrode deposition shows the worst stability; conversely, the device that annealed after top electrode deposition has the best coefficient of variation of the LRS and HRS which is 4.69% and 78.8%, respectively. Electrical and materials analyses were conducted to understand this phenomenon. This study provides insight into the compatibility of ECM in CMOS post-processing.

Resistive Switching in the Cu/Si/SiO2/CdS/CuO/Cu Structure Fabricated at Room Temperature Haneafa Yahya Najm

This work investigates CuO and CdS (material as nanoparticles mixed with a polymer (Cellulose Acetate)) – based ReRAM having stable resistive switching. It also investigates a new composition of a memory which is constructed with silicon as a pedestal, silicon oxide SiO2 thermally grown on it and active materials that include of (CuO material as nanoparticles mixed with a polymer (Cellulose Acetate) layer) sandwiched between two electrodes using similar material and CdS layer as a semiconductor n-type. ReRAM memory cell is a structure such as a capacitor that is consist of semiconducting transition metal oxides or insulating exhibiting inverses resistive switching on applying voltage pulses .The mixed material was coated as a thin layer by using Spin-Coating Instrument. this structure can be switched between low- resistance state (LRS) and high resistance state(HRS);therefore, The present structure behaves as unipolar resistive switching. The resistive behavior will be affected by the top electrode area. This effect occurs more in big top electrode area (TEL=15.896mm2) where, the constituting voltage (Vforming) is inversely proportionately with respect to the top electrode area (A) .Also the (HRS) is inversely proportioned with the (A). The complying current (Icc=20mA) is used for protect the device from the damageable. The fabricated composition has many prosperities, such as Vforming = 7.3volt, Vset = 4volt, VReset = 1.7volt, Finally, the resistance ratio (Rratio) is proportioned directly with the(A) and equal Rratio=157.48 so, this ratio is enough to distinguish amongst the low resistance and the high resistance in a circuit design

Reconfigurable self-powered deep UV photodetectors based on ultrawide bandgap ferroelectric ScAlN

The efficient photoelectric conversion based on the ferroelectric property of a material has attracted widespread attention in advanced optoelectronic systems. Such an electrically reconfigurable photovoltaic effect offers a unique opportunity for the development of self-powered ultraviolet (UV) photodetectors for a broad range of applications from the military to human health and the environment. To date, however, the low performance metrics of such photodetectors have hindered their integration with existing platforms. By exploring the unique optoelectronic properties of an ultrawide bandgap nitride ferroelectric (ScAlN), we demonstrate, for the first time, polarization dependent high-performance self-powered deep UV photodetectors. The responsivity at 193 nm illumination reached up to a maximum of 15 mA/W with a detectivity of 1.2 × 1011 Jones at an extremely low illumination intensity of 0.12 mW/cm2. Furthermore, the photodetectors exhibit wake-up free and reconfigurable photo-response, and fast and stable switching response time (&amp;lt;0.06 s) with excellent rejection to UV-A and visible illumination. The significant findings related to the growth, fabrication, and characterization reported in this work construct a viable route to realize unprecedentedly high performance self-powered ferroelectric UV photodetectors toward energy-efficient applications.

Ultra-strong ionic liquid-based polymer composite electrolyte for high performance electrochromic devices

Polymer electrolytes are the key composite for all-solid electrochromic devices due to their unique properties including high ionic conductivity, good flexibility, etc. However, such applications are still impeded by the poor mechanical strength. In this study, novel quasi-solid polymer/ionic liquid composite electrolyte is constructed and the tensile strength is greatly enhanced by coupling epoxy composite with glass fibers (GFs) as the reinforcement. The tensile strength of the composite electrolyte is tripled and reaches 7.6 MPa after optimizing the content of GFs with the ionic conductivity of 1.75 × 10 −5 S cm −1 . Then, a dual-coloring electrochromic device fabricated with the composite electrolyte presents excellent switching stability (18000 cycles, >180000 s), fast response (˂2 s), ultra-high coloring efficiency (η = 451 cm 2 /C) and low driving voltage (±1 V). In addition, a substrate-free and flexible electrochromic device based on the composite electrolyte is successfully assembled, which demonstrates remarkable electrochromic behaviors, unique flexibility and mechanical stability. This work may promote the development of low-cost, easily-assembled, ultrahigh-flexible and high-performance electrochromic devices. • A ultra-strong composite electrolyte is fabricated by introducing glass fibers into the polymer matrix. • A electrochromic device based on the composite electrolyte demonstrates high optical contrast, fast switching response, and high color efficiency. • The high strength of the composite electrolyte make it possible to construct substrate-free and cost-effective ECDs.