Water dissolvable MoS₂ quantum dots/PVA film as an active material for destructible memristors

Sarkar S.S., Mukherjee S., Khatri R.K., Ray S.K.

The characteristics of a novel 0D/3D heterojunction photodetector fabricated using solution-processed colloidal MoS2 quantum dots (QDs) on GaAs is presented. MoS2 QDs with a dimension of ∼2 nm, synthesized by a standard sono-chemical exfoliation process with 2D layers have been used for the purpose. The microscopic and spectroscopic studies confirmed the formation of semiconducting (2H phase) MoS2 QDs. The photodetectors were fabricated using n-GaAs substrates with two different doping concentrations resulting in n-n heterojunctions between n-type 0D MoS2 QDs and bulk n-GaAs. The devices fabricated using GaAs with a higher doping concentration, showed an increase in the reverse current of the order of ∼102 upon illumination, while the same with a lower doping concentration showed an increase of the order of ∼103. All the heterojunction photodetector devices show a broadband operation over the visible wavelength range of 400-950 nm, with a peak responsivity of the devices being observed at 500 nm. The peak responsivity and detectivity are found to be ∼400 mA W-1 and ∼4 × 1012 Jones, respectively, even without any external applied bias, which are useful for self-powered photodetection. The results indicate that colloidal MoS2/GaAs based hybrid heterostructures provide a platform for fabricating broadband photodetectors by using highly absorbing MoS2 QDs, which may show the pathway towards next-generation optoelectronic devices with superior detection properties.

Chen R., Xu J., Lao M., Liang Z., Chen Y., Zhong C., Huang L., Hao A., Ismail M.

Chen Y., Wang H., Zhang Y., Li R., Chen C., Zhang H., Tang S., Liu S., Chen X., Wu H., Lv R., Sheng X., Zhang P., Wang S., Yin L.

Transient electronics is an emerging technology that enables unique functional transformation or the physical disappearance of electronic devices, and is attracting increasing attention for potential applications in data secured hardware as an ultimate solution against data breaches. Developing smart triggered degradation modalities of silicon (Si) remain the key challenge to achieve advanced non-recoverable on-demand transient electronics. Here, we present a novel electrochemically triggered transience mechanism of Si by lithiation, allowing complete and controllable destruction of Si devices. The depth and microstructure of the lithiation-affected zone over time is investigated in detail and the results suggest a few hours of lithiation is sufficient to create microcracks and significantly promote lithium penetration. Finite element models are proposed to confirm the mechanism. Electrochemically triggered degradation of thin film Si ribbons and Si integrated circuit chips with metal-oxide-semiconductor field-effect transistors from a commercial 0.35 micrometer complementary metal-oxide-semiconductor technology node is performed to demonstrate the potential applications for commercial electronics. This work opens new opportunities for versatile triggered transience of Si-based devices for critical secured information systems and green consumer electronics.

Shanmugaraj K., John S.A.

Bilirubin is an important biomarker in the diagnosis and prognosis of patients with liver disorders. Herein, we report a simple, rapid, sensitive and selective quantitative determination of bilirubin using molybdenum disulfide quantum dots (MoS2 QDs) as a probe. The MoS2 QDs were synthesized through a hydrothermal route by using sodium molybdate and cysteine as the starting materials. The obtained MoS2 QDs exhibits strong luminescence property and excellent stability. The HR-TEM image shows that the size of the prepared MoS2 QDs was 2.4 nm with a spherical morphology. The MoS2 QDs emit intense blue photoluminescence (with excitation/emission peaks at 310/392 nm) under UV light and the fluorescence of MoS2 QDs was drastically quenched by the addition of bilirubin. The Förster resonance energy transfer (FRET) and inner filter effect (IFE) between MoS2 QDs and bilirubin resulted in the fluorescence quenching of MoS2 QDs. The present method demonstrated high sensitivity towards bilirubin with the limit of detection (LOD) of 2.1 nM (S/N = 3). The MoS2 QDs probe showed remarkable selectivity to bilirubin over other possible interferences. Moreover, the present fluorophore was successfully utilized for the detection of bilirubin in human serum and urine samples. QDs based fluorescence probe for the recognition of bilirubin is reported for the first time.

Sahatiya P., Shinde A., Kadu A., Badhulika S.

Electronic systems that can respond to the user-defined circumstances from a distant location hold enormous potential in disposable devices, secured memories, restorable environmental monitoring etc. related applications which cannot be achieved by conventional silicon technology. This paper is the first demonstration of wirelessly destructible ultraviolet photodetector based on Itaconic acid functionalized water soluble ZnS on flexible polyvinyl alcohol (PVA) substrate wherein all of the device elements dissolve and/or disintegrate upon immersion in water triggered using smartphone assisted Android application. The user can wirelessly destroy the sensor anytime or the sensor can be programmed to be destroyed after performing its task. Use of graphene as both contacts as well as a transport layer enables superior photodetection while making the fabrication simple, low-cost and cleanroom free which disintegrates from the device upon dissolution in water. The fabricated transient, flexible photodetector exhibited a remarkable responsivity of 1.08 mA/W and rise time and fall times of 6.1 s and 8.23 s respectively which could be ascribed to the large electric field created at the ZnS/graphene schottky barrier. Dissolution and disintegration of the fabricated sensor demonstrate complete transience in 10 mins. The study presented here opens up numerous possibilities for applications of wireless transient photodetectors in environmental monitoring, health care, security and consumer electronics.

Perumal Veeramalai C., Li F., Guo T., Kim T.W.

A hydrothermal synthesis of molybdenum disulphide (MoS2) monolayer QDs and their application to flexible memristive devices have been demonstrated.

Zhong Y., Xue F., Wei P., Li R., Cao C., Yi T.

We report a facile and sensitive method for the detection of alkaline phosphatase (ALP) activity in serum and live cells using molybdenum disulfide quantum dots (MoS2 QDs) based on the Inner Filter Effect (IFE).

Zhou Z., Mao H., Wang X., Sun T., Chang Q., Chen Y., Xiu F., Liu Z., Liu J., Huang W.

A transient and flexible polymer memristor was fabricated.

Ji X., Song L., Zhong S., Jiang Y., Lim K.G., Wang C., Zhao R.

Physically transient electronics have attracted increasing attention recently due to their potential as the basis for building “green” electronics and biomedical devices. In the development of tran...

Won S.M., Koo J., Crawford K.E., Mickle A.D., Xue Y., Min S., McIlvried L.A., Yan Y., Kim S.B., Lee S.M., Kim B.H., Jang H., MacEwan M.R., Huang Y., Gereau R.W., et. al.

Emerging classes of bioresorbable electronic materials serve as the basis for active biomedical implants that are capable of providing sensing, monitoring, stimulating, and other forms of function over an operating period matched to biological processes such as wound healing. These platforms are of interest because subsequent dissolution, enzymatic degradation, and/or bioresorption can eliminate the need for surgical extraction. This report introduces natural wax materials as long-lived, hydrophobic encapsulation layers for such systems, where biodegradation eventually occurs by chain scission. Studies of wax stability as an encapsulation material demonstrate the ability to retain operation of underlying biodegradable electronic systems for durations between a few days to a few weeks during complete immersion in aqueous solutions in ex-vivo physiological conditions. Electrically conductive composites result from the addition of tungsten micro/nanoparticles, as a conductive, printable paste with similar lifetimes. Demonstrations of these materials in partially biodegradable wireless light-emitting diodes and near-field communication circuits illustrate their use in functional bioresorbable electronic systems. Investigations in animal models reveal no signs of toxicity or other adverse biological responses.

Wang Q., Huang J., Sun H., Ng Y.H., Zhang K., Lai Y.

TiO2 nanotube arrays (TiO2 NTAs) decorated with molybdenum disulfide quantum dots (MoS2 QDs) were synthesized by a facile electrodeposition method and used as a composite photocatalyst. MoS2 QDs/TiO2 NTAs showed enhanced photocatalytic activity compared with pristine TiO2 NTAs for solar light-promoted H2 evolution without adding any sacrificial agents or cocatalysts. The photocatalytic activity was influenced by the amount of MoS2 QDs coated on TiO2 NTAs. The optimal composition showed excellent photocatalytic activity, achieving H2 evolution rates of 31.36, 5.29, and 1.67 μmol cm-2 h-1 corresponding to ultraviolet (UV, λ760) illumination, respectively. The improved photocatalytic activity was attributed to the decreased bandgap and the surface plasmonic properties of MoS2 QDs/TiO2 NTAs, which promoted electron-hole pair separation and the absorption capacity for Vis and NIR light. This study presents a facile approach for fabricating MoS2 QDs/TiO2 NTA heterostructures for efficient photocatalytic H2 evolution, which will facilitate the development of designing new photocatalysts for environment and energy applications.

Wang Y., Zhang P., Lu Q., Wang Y., Fu W., Tan Q., Luo W.

A method is described for the fluorometric determination of hypochlorite. It is making use of molybdenum disulfide quantum dots (MoS2 QDs) as a fluorescent probe. The QDs are prepared by hydrothermal reaction of sodium molybdate with glutathione. They possess diameters typically ranging from 1.4 to 3.8 nm, excellent stability in water, and blue photoluminescence (with excitation/emission peaks located at 315/412 nm and a quantum yield of 3.7%). The fluorescence of the QDs is statically quenched by hypochlorite, and the Stern-Volmer plot is linear. Hypochlorite can be detected in the 5–500 μM concentration range with a 0.5 μM detection limit. The method has been successfully applied to the determination of hypochlorite in spiked samples of tap water, lake water, and commercial disinfectants.

Lin Q., Hu W., Zang Z., Zhou M., Du J., Wang M., Han S., Tang X.

Huang X.

Bioresorbable electronics is a new type of electronics technology that can potentially lead to biodegradable and dissolvable electronic devices to replace current built-to-last circuits predominantly used in implantable devices and consumer electronics. Such devices dissolve in an aqueous environment in time periods from seconds to months, and generate biological safe products. This paper reviews materials, fabrication techniques, and applications of bioresorbable electronics, and aims to inspire more revolutionary bioresorbable systems that can generate broader social and economic impact. Existing challenges and potential solutions in developing bioresorbable electronics have also been presented to arouse more joint research efforts in this field to build systematic technology framework.

Wang X., Wu Q., Jiang K., Wang C., Zhang C.

Transition metal chalcogenides, especially molybdenum disulfide, have recently got wide attention from researchers because of their unique intrinsic characteristics. However, until now, few literatures have reported the photoluminescent MoS2 materials and their applications. In this work, we reported a bottom-up strategy to synthesize water-soluble molybdenum disulfide quantum dots (MoS2 QDs) through a facile hydrothermal route using sodium molybdate and glutathione as Mo and S sources. The obtained MoS2 QDs show blue emission with a high quantum yield (∼10.3%) and robust dispersibility and storage stability optical property in aqueous solution. During the experiment, we found that in the presence of hydrogen peroxide (H2O2), the fluorescence of MoS2 QDs is quenched due to the interaction between H2O2 and MoS2 QDs. Simultaneously, glucose oxidase catalyzes the oxidation of glucose to produce gluconic acid and H2O2, so we can use this probe to detect glucose. By reason of the high zymolyte specificity of glucose oxidase, the detection of glucose has good selectivity and sensitivity with a detection limit of 5.16 μM. Finally, the method is successfully applied for detection of glucose in fetal bovine serum samples.

Sahu G., Chakraborty C., Roy S., Banerjee S.

Abstract The article discusses the time evolution and growth mechanics of MoS2 quantum dots (QD) with variable precursor concentration during a bottom-up process for a hydrothermal reaction. At a constant reaction time (14 hours taken as reference), we observe a special value of concentration C * that generates the highest average QD size, which interestingly produces smaller QDs on either side of C *. These observations have been supported by morphological and photophysical studies, indicating that the compactness of the systems is impacted. This prompts us to investigate the entire growth dynamics using a statistical method like fractal analysis. We also observe a non-monotonic behaviour of bandgap with a minimum value (4.69 eV) as well as a distinct peak (≈450 nm) for the photoluminescence (PL) spectra, both occurring at the same concentration C *. Subsequently, the spatial correlation in the QD sheets that formed through aggregation during the process has been been explored through fractal analysis, yielding the highest fractal dimension, d f  =  1.97 at C *. The non-monotonic behaviour of d f around C * has been attributed to an interplay of aggregation and fragmentation of the sheets combined with Ostwald ripening. As it appears that the growth dynamics of the system may be viewed in a statistical manner we further apply numerical simulations based on random walk on a 2D lattice to understand the formation of the QD sheets. The results are found to be in good agreement with the experimental results, both with increasing reaction time and for different precursor concentrations.

Jiao Z., Zhou X., Yu J., Lan X., Shi Y., Li J., Liu B., Li Y., Chen G., Hu R., Zhang P., Xu B.

By ultrasonic-assisted liquid-phase exfoliation, MoS2 nanosheets were reduced in size to quantum dots to obtain MoS2 QDs. And they were embedded in PVA to construct RRAM devices to explore the effect of MoS2 size reduction on RS performance.

Patil A.R., Dongale T.D., Pedanekar R.S., Sutar S.S., Kamat R.K., Rajpure K.Y.

The memristors offer significant advantages as a key element in non-volatile and brain-inspired neuromorphic systems because of their salient features such as remarkable endurance, ability to store multiple bits, fast operation speed, and extremely low energy usage. This work reports the resistive switching (RS) characteristics of the hydrothermally synthesized iron tungstate (FeWO4) based thin film memristive device. The detailed physicochemical analysis was investigated using Rietveld's refinement, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) techniques. The fabricated Ag/FWO/FTO memristive device exhibits bipolar resistive switching (BRS) behavior. In addition, the devices exhibit negative differential resistance (NDR) at both positive and negative bias. The charge-flux relation portrayed the non-ideal or memristive nature of the devices. The reliability in the RS process was analyzed in detail using Weibull distribution and time series analysis techniques. The device exhibits stable and multilevel endurance and retention characteristics which demonstrates the suitability of the device for the high-density non-volatile memory application. The current conduction of the device was dominated by Ohmic and trap controlled-space charge limited current (TC-SCLC) mechanisms and filamentary RS process responsible for the BRS in the device. In a nutshell, the present investigations reveal the potential use of the iron tungstate for the fabrication of memristive devices for the non-volatile memory application.

Rempel Andrey A., Ovchinnikov Oleg V., Weinstein Ilya A., Rempel Svetlana V., Kuznetsova Yulia V., Naumov Andrei V., Smirnov Mikhail S., Eremchev Ivan Yu., Vokhmintsev Alexander S., Savchenko Sergey S.

Quantum dots are the most exciting representatives of nanomaterials. They are synthesized using advanced methods of nanotechnology pertaining to both inorganic and organic chemistry. Quantum dots possess unique physical and chemical properties; therefore, they are used in very different fields of physics, chemistry, biology, engineering and medicine. It is not surprising that the Nobel Prize in chemistry in 2023 was given for discovery and synthesis of quantum dots. This review addresses modern methods for the synthesis of quantum dots and their optical properties and practical applications. In the beginning, a short insight into the history of quantum dots is given. Many gifted scientists, including chemists and physicists, were engaged in these studies. The synthesis of quantum dots in solid and liquid matrices is described in detail. Quantum dots are well-known owing to their unique optical properties; that is why the attention in the review is focused on the quantum-size effect. The causes for fascinating blinking of quantum dots and techniques for observation of a single quantum dot are considered. The last part of the review describes mportant applications of quantum dots in biology, medicine and quantum technologies.The bibliography includes 772 references.

Udaya Mohanan K.

Neuromorphic computing has emerged as an alternative computing paradigm to address the increasing computing needs for data-intensive applications. In this context, resistive random access memory (RRAM) devices have garnered immense interest among the neuromorphic research community due to their capability to emulate intricate neuronal behaviors. RRAM devices excel in terms of their compact size, fast switching capabilities, high ON/OFF ratio, and low energy consumption, among other advantages. This review focuses on the multifaceted aspects of RRAM devices and their application to brain-inspired computing. The review begins with a brief overview of the essential biological concepts that inspire the development of bio-mimetic computing architectures. It then discusses the various types of resistive switching behaviors observed in RRAM devices and the detailed physical mechanisms underlying their operation. Next, a comprehensive discussion on the diverse material choices adapted in recent literature has been carried out, with special emphasis on the benchmark results from recent research literature. Further, the review provides a holistic analysis of the emerging trends in neuromorphic applications, highlighting the state-of-the-art results utilizing RRAM devices. Commercial chip-level applications are given special emphasis in identifying some of the salient research results. Finally, the current challenges and future outlook of RRAM-based devices for neuromorphic research have been summarized. Thus, this review provides valuable understanding along with critical insights and up-to-date information on the latest findings from the field of resistive switching devices towards brain-inspired computing.

Sahu G., Chakraborty C., Roy S., Banerjee S.

The article discusses the novel fractal nature of hydrothermally synthesized Molybdenum Disulfide (MoS2) Quantum Dots (QDs), where the key parameter controlling the process is the 'reaction time’. This parameter is adjusted from 7 to 30 hours, including five intermediate values, while keeping all other synthesis conditions constant. The study employs various structural, morphological, and optical techniques, including X-ray diffraction (XRD), X-ray photoelectron Spectroscopy (XPS), High-Resolution Transmission Electron Microscopy (HRTEM) equipped with Selected Area Electron Diffraction (SAED), Scanning Transmission Electron Microscopy (STEM), UV-Vis, and photoluminescence (PL) spectroscopy to track the evolution of MoS2 samples with changing reaction times. The average size of the QDs exhibits a trend of increase followed by a decrease with longer reaction times. This trend is also compared with band gap calculations. STEM images indicate that shorter reaction times lead to the formation of MoS2 sheets, while extended reaction times cause these sheets to fragment into MoS2 QDs. The concept of “compactness” in the system is explored and analyzed using fractal analysis, a statistical tool. The observations from PL, absorption, and STEM align with the time-evolved fractal dimensional analysis, demonstrating the synthesis dynamics.

Zhang Q., Jiang Q., Fan F., Liu G., Chen Y., Zhang B.

Selamneni V., Sahatiya P.

Over the last two decades, low-dimensional nanomaterials such as zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D) have been used as functional materials in the development of photodetectors due to their extraordinary electronic and optical properties. However, developing broadband photodetectors with high responsivity with a single low-dimensional material is still an existing challenge. To overcome this, researchers have started exploring the mixed-dimensional van der Waals (vdW) heterostructures such as 0D-2D, 1D-2D and 2D-3D based photodetectors due to their wide absorption in the electromagnetic spectrum, low dark current, ultrahigh photoresponsivity, and fast response time. This review highlights the comprehensive compilation of transition-metal dichalcogenides (TMDs) based mixed-dimensional vdW heterostructure broadband photodetectors. First a brief insight into the fundamentals of photodetectors such types of photodetectors, photodetection mechanism, performance parameters, and type of band alignment is explained. Then the recent progress in various mixed-dimensional vdW heterostructures is summarized. Finally, challenges are discussed and directions for further development of mixed-dimensional broadband photodetectors are anticipated.

Wang Z., Wang W., Liu P., Liu G., Li J., Zhao J., Zhou Z., Wang J., Pei Y., Zhao Z., Li J., Wang L., Jian Z., Wang Y., Guo J., et. al.

As the emerging member of zero-dimension transition metal dichalcogenide, WSe2 quantum dots (QDs) have been applied to memristors and exhibited better resistance switching characteristics and miniaturization size. However, low power consumption and high reliability are still challenges for WSe2 QDs-based memristors as synaptic devices. Here, we demonstrate a high-performance, superlow power consumption memristor device with the structure of Ag/WSe2 QDs/La0.3Sr0.7MnO3/SrTiO3. The device displays excellent resistive switching memory behavior with a ROFF/RON ratio of ~5 × 103, power consumption per switching as low as 0.16 nW, very low set, and reset voltage of ~0.52 V and~ -0.19 V with excellent cycling stability, good reproducibility, and decent data retention capability. The superlow power consumption characteristic of the device is further proved by the method of density functional theory calculation. In addition, the influence of pulse amplitude, duration, and interval was studied to gradually modulating the conductance of the device. The memristor has also been demonstrated to simulate different functions of artificial synapses, such as excitatory postsynaptic current, spike timing-dependent plasticity, long-term potentiation, long-term depression, and paired-pulse facilitation. Importantly, digit recognition ability based on the WSe2 QDs device is evaluated through a three-layer artificial neural network, and the digit recognition accuracy after 40 times of training can reach up to 94.05%. This study paves a new way for the development of memristor devices with advanced significance for future low power neuromorphic computing.

Wang L., Zhang Y., Zhang P., Wen D.

Organic-resistance random access memory has high application potential in the field of next-generation green nonvolatile memory. Because of their biocompatibility and environmental friendliness, natural biomaterials are suitable for the fabrication of biodegradable and physically transient resistive switching memory devices. A flexible memory device with physically transient properties was fabricated with silver ions and egg albumen composites as active layers, which exhibited characteristics of write-once-read-many-times (WORM), and the incorporation of silver ions improved the ON/OFF current ratio of the device. The device can not only complete the logical operations of “AND gate” and “OR gate”, but its active layer film can also be dissolved in deionized water, indicating that it has the characteristics of physical transients. This biocompatible memory device is a strong candidate for a memory element for the construction of transient electronic systems.

Liu L., Cheng S., Chen W., Ren S., Kang X., Zhao X.

Abstract MoS2–polymer-based memory devices have attracted significant interest owing to their mechanical flexibility, convenient solution processability, and affordability. These devices exhibit bipolar resistive switching behavior, and their switching relies on the polarity of the applied bias. This paper presents a memory device in which a MoS2–polyvinyl alcohol (PVA) hybrid film is sandwiched between Ag and Pt electrodes. The developed Ag/MoS2–PVA/Pt device manifests typical unipolar resistive switching (URS) behavior and nonvolatile rewritable memory performance with a low operating voltage, large ON/OFF ratio (105), and multilevel cell storage ability. Notably, 1T-phase MoS2 is crucial for the URS behavior, and this switching behavior can be ascribed to the charge trapping as well as the Joule-heating-induced de-trapping of the S vacancies associated with 1T MoS2. These findings can facilitate the development of new designs for high-performance, high-density data storage.

Rani A., Khot A.C., Jang I.G., Kim T.G.

This paper reports on the synthesis of vacancy-assisted carbon-packed MoSSe (C@MoSSe) nanospheres and their use in memristor and neuromorphic devices. The heterostructure C@MoSSe nanospheres were fabricated using simple hydrothermal and sonication methods to synthesize large-scale, uniform C@MoSSe films on flexible substrates. The carbon skeleton, tightly adhered to the heterostructure MoSSe nanospheres, helped assign low sp 2 characteristics to the vacancies on the defective surfaces of the MoSSe nanospheres, thereby facilitating the realization of highly stable memristor and neuromorphic performance. In addition, the defects in the crystal lattice of the pure phase of MoSSe increased the band gap (around 4.39 eV) to be larger than the bulk and Janus structure of MoSSe (1.2 and 1.9 eV, respectively), resulting in carrier transport owing to trap filling. The C@MoSSe-based memristor successfully mimicked the basic and complex properties of synaptic plasticity, with a critical time window of around 460 μs, lower than that of the human brain. Bipolar memory performance, such as a high on/off current ratio, a reasonably low operating voltage, and stability, depended on the thickness of the C@MoSSe layers. The findings demonstrate the application potential of C@MoSSe-based memristors and can promote the realization of large-scale neuromorphic circuits. • Carbon-packed MoSSe (C@MoSSe) nanospheres for memristor and synapse devices. • C@MoSSe is fabricated using hydrothermal and density-gradient centrifugation method. • The memristor shows excellent endurance and retention due to the sp 2 nature of carbon. • A series of synaptic actions with a 460 μs time window are successfully mimicked.

Li X., Pei Y., Zhao Y., Song H., Zhao J., Yan L., He H., Lu S., Yan X.

Carbon quantum dots (CDs) were doped into the memristor to prepare Ag/HfO2/CDs/Pt devices, which improved the uniformity of device parameters and accomplished simulations of supervised learning, interest-based learning activities and preview and review learning method.

Roy S., Ganeshan S.K., Pal S., Chakraborty C.

Bistable electrochromic (EC) display with long EC memory has been a much-anticipated goal owing to its zero-energy consumption when maintaining the colored or bleached state when used in smart windows. However, it is very challenging to engineer the structure of the materials to accomplish a long EC memory along with high optical contrast, durability, switching fastness, and coloration efficiency which are of significance for fabricating the electrochromic devices with essentially power efficiency. Herein, we have judiciously incorporated the charge trapping MoS 2 quantum dots (QDs) to prepare an electrochromic nanocomposite (polyFe-QD-10) of an Fe 2+ -based metallo-supramolecular EC polymer (polyFe) for the targeted enhancement of EC memory than the pristine polyFe polymer. The polyFe-QD-10 based electrochromic device (ECD) exhibits more cycle durability as it produced no loss in ΔT after the measurement of 100 cycle, while pristine polyFe-based ECD produced 14% loss in similar 100 cycle. The prototype ECD with polyFe-QD-10 film is also demonstrated with fast switching time (3.3 s for bleaching and 0.78 s for coloring), and good coloration efficiency (242.2 cm 2 C −1 ). Remarkably, the ECD based on polyFe-QD-10 composite displays higher EC memory in open circuit condition as it takes 32 min for 90% reappearance of the original purple color after complete bleaching, while the pristine polyFe based ECD regains 90% of the transmittance of the color state only in 15 min. The strategy reported here presents the polyFe-MoS 2 QD composite thin film an encouraging candidate for developing power efficient electrochromic information displays and smart windows. • MoS 2 quantum dots (QDs) enhance the electrochromic (EC) memory of Fe-based polymer. • Charge trapping property of MoS 2 QD improves the EC memory of nanocomposite device. • The solid-state device shows fast and durable electrochromism with high coloration efficiency. • A facile and robust strategy to enhance electrochromic memory as well as power efficiency.

Bokka N., Selamneni V., Adepu V., Jajjara S., Sahatiya P.

Abstract Electronic devices that are biodegradable, water soluble and flexible and are fabricated using biodegradable materials are of great importance due to their potential application in biomedical implants, personal healthcare etc. Moreover, despite the swift growth of semiconductor technologies and considering a device’s shell life of two years, the subject of electronic waste (E-waste) disposal has become a major issue. Transient electronics is a rapidly expanding field that solves the issue of E-waste by destroying the device after usage. The device disintegration can be caused by a multitude of triggering events, an example is that the device totally dissolves and/or disintegrates when submerged in water. This technology enables us to utilize electronic devices for a set amount of time before quickly destroying them, lowering E-waste significantly. This review will highlight the recent advancement in water-soluble flexible electronic devices with more focus on functional materials (water insoluble), fabrication strategies and transiency understanding with special importance on areas where these devices exhibit potential application in flexible and wearable electronic devices which includes field effect transistors, photodetectors, memristors and sensors for personal healthcare monitoring.