Composite-based Devices Research Articles

Novel carboxylic-MWCNTs photoresist for fabricating sub-diffraction polymer nanowires via STED lithography

A novel composite photoresist, derived from acrylates and carboxylic-functionalized multi-walled carbon nanotubes (MWNTs-COOH), has been developed for the fabrication of sub-diffraction-sized polymer nanowires using STED-inspired lithography. The MWNTs-COOH dispersed in highly cross-linking acrylate monomers benefits to a reduced inhibition laser power for improving lithography. With the MWNTs-COOH, the inhibition laser power is decreased from 5 mW to 3 mW, while the achievable minimum feature size is increased from 121 nm to 48 nm. This innovative approach holds significant promise for the development of sub-diffraction MWCNTs/polymer composite-based devices in the fields of Micro-Electro-Mechanical Systems (MEMS) and Nano-Electro-Mechanical Systems (NEMS).

Macromolecular sensing motors from conducting polymers: Polyaniline/methylcellulose composites as stable current sensing supercapacitors

Sensing motors and supercapacitors are pivotal in empowering smart systems, honing energy management, and facilitating the seamless integration of responsive electronics. Harnessing the electrochemistry of methylcellulose-polyaniline (MC/PANI) composites, this research delves into their potential applications as reactive current sensing supercapacitors with single connectivity. The electrochemical traits of pristine polyaniline (PANI) and MC/PANI composites were analyzed and assessed for their potential applications in sensors and energy storage devices. With a specific capacitance of 300Fg−1, the MC/PANI_B3 composite-based device retained 87.01 % capacitance after 2000 cycles. Besides, based on electrical energy as the sensing parameter, the composite exhibited augmented cathodic and anodic current sensitivity of 8.77 mJmA−1 and -8.86 mJmA−1, respectively. The ameliorated supercapacitor and current sensing parameters of MC/PANI_B3 are ascribed to the percolation threshold content of the conducting phase, which is endowed with optimal hydrogen bond-mediated interactions with methylcellulose (MC), thus confers an expanded chain conformation.

A Novel Spinel Ferrite-Hexagonal Ferrite Composite for Enhanced Magneto-Electric Coupling in a Bilayer with PZT.

The magnetoelectric effect (ME) is an important strain mediated-phenomenon in a ferromagnetic-piezoelectric composite for a variety of sensors and signal processing devices. A bias magnetic field, in general, is essential to realize a strong ME coupling in most composites. Magnetic phases with (i) high magnetostriction for strong piezomagnetic coupling and (ii) large anisotropy field that acts as a built-in bias field are preferred so that miniature, ME composite-based devices can operate without the need for an external magnetic field. We are able to realize such a magnetic phase with a composite of (i) barium hexaferrite (BaM) with high magnetocrystalline anisotropy field and (ii) nickel ferrite (NFO) with high magnetostriction. The BNx composites, with (100 - x) wt.% of BaM and x wt.% NFO, for x = 0-100, were prepared. X-ray diffraction analysis shows that the composites did not contain any impurity phases. Scanning electron microscopy images revealed that, with an increase in NFO content, hexagonal BaM grains become prominent, leading to a large anisotropy field. The room temperature saturation magnetization showed a general increase with increasing BaM content in the composites. NFO rich composites with x ≥ 60 were found to have a large magnetostriction value of around -23 ppm, comparable to pure NFO. The anisotropy field HA of the composites, determined from magnetization and ferromagnetic resonance (FMR) measurements, increased with increasing NFO content and reached a maximum of 7.77 kOe for x = 75. The BNx composite was cut into rectangular platelets and bonded with PZT to form the bilayers. ME voltage coefficient (MEVC) measurements at low frequencies and at mechanical resonance showed strong coupling at zero bias for samples with x ≥ 33. This large in-plane HA acted as a built-in field for strong ME effects under zero external bias in the bilayers. The highest zero-bias MEVC of ~22 mV/cm Oe was obtained for BN75-PZT bilayers wherein BN75 also has the highest HA. The Bilayer of BN95-PZT showed a maximum MEVC ~992 mV/cm Oe at electromechanical resonance at 59 kHz. The use of hexaferrite-spinel ferrite composite to achieve strong zero-bias ME coupling in bilayers with PZT is significant for applications related to energy harvesting, sensors, and high frequency devices.

Self-Polarized P(VDF-TrFE)/Carbon Black Composite Piezoelectric Thin Film.

Self-polarized energy harvesting materials have seen increasing research interest in recent years owing to their simple fabrication method and versatile application potential. In this study, we systematically investigated self-polarized P(VDF-TrFE)/carbon black (CB) composite thin films synthesized on flexible substrates, with the CB content varying from 0 to 0.6 wt.% in P(VDF-TrFE). The presence of -OH functional groups on carbon black significantly enhances its crystallinity, dipolar orientation, and piezoelectric performance. Multiple characterization techniques were used to investigate the crystalline quality, chemical structure, and morphology of the composite P(VDF-TrFE)/CB films, which indicated no significant changes in these parameters. However, some increase in surface roughness was observed when the CB content increased. With the application of an external force, the piezoelectrically generated voltage was found to systematically increase with higher CB content, reaching a maximum value at 0.6 wt.%, after which the sample exhibited low resistance. The piezoelectric voltage produced by the unpoled 0.6 wt.% CB composite film significantly exceeded the unpoled pure P(VDF-TrFE) film when subjected to the same applied strain. Furthermore, it exhibited exceptional stability in the piezoelectric voltage over time, exceeding the output voltage of the poled pure P(VDF-TrFE) film. Notably, P(VDF_TrFE)/CB composite-based devices can be used in energy harvesting and piezoelectric strain sensing to monitor human motions, which has the potential to positively impact the field of smart wearable devices.

High-Selectivity Hydrogen Gas Sensors based on Mesoporous PbOx-ZnO Nanocomposites.

Hydrogen heralded as a promising renewable and environmentally friendly energy carrier, carries inherent risks owing to its highly flammable nature. A mere 4 % concentration of hydrogen in the air can trigger an explosion. To counteract this peril, a composite material comprising PbOX-ZnO (2 : 1) was synthesized, characterized, and subsequently employed to fabricate a hydrogen sensing device. Various analytical tools were used to characterize as-deposited materials, including X-ray diffraction, Scanning electron microscopy /Energy Dispersive X-ray Spectroscopy, Transmission electron microscopy UV-Vis Reflectance Spectroscopy and Fourier-transform infrared spectroscopy. The device exhibited favorable properties, such as good selectivity, stability, and a low detection limit for hydrogen. At ambient room temperature, the device demonstrated a sensing signal reaching 468.7, with a response time (T90) of 155 seconds and a recovery time (Tr90) of 69 seconds when exposed to a hydrogen concentration of 5 ppm. This performance underscores the device's rapid and effective response to hydrogen exposure. Moreover, the PbOX-ZnO (2 : 1) composite-based device exhibited a detection limit of 2.4 ppm, functioning accurately within a linear range spanning from 5 ppm to 50 ppm. This capability confirms its precision in accurately detecting hydrogen concentrations within this designated range.

Giant Piezoelectric Output and Stability Enhancement in Piezopolymer Composites with Liquid Metal Nanofillers.

Integrating nanomaterials into the polymer matrix is an effective strategy to optimize the performance of polymer-based piezoelectric devices. Nevertheless, the trade-off between the output enhancement and stability maintenance of piezoelectric composites usually leads to an unsatisfied overall performance for the high-strength operation of devices. Here, by setting liquid metal (LM) nanodroplets as the nanofillers in a poly(vinylidene difluoride) (PVDF) matrix, the as-formed liquid-solid/conductive-dielectric interfaces significantly promote the piezoelectric output and the reliability of this piezoelectric composite. A giant performance improvement featured is obtained with, nearly 1000% boosting on the output voltage (as high as 212V), 270% increment on the piezoelectric coefficient (d33 ∼51.1pCN-1 ) and long-term reliability on both structure and output (over 36000 cycles). The design of a novel heterogenous interface with both mechanical matching and electric coupling can be the new orientation for developing high performance piezoelectric composite-based devices.

On generalized Rayleigh waves in a pre-stressed piezoelectric medium

This research aims to study the different phenomena of generalized Rayleigh waves (RWs) in composite structures with piezoelectric material and corrugated surfaces. A thin piezoelectric layer that is precisely attached to an elastic substrate with initial stresses makes up the structure under consideration. By resolving the related electromechanical field equations, expressions for the displacement potential function are produced for both the elastic substrate and the piezoelectric layer. The frequency equations of the studied wave have been discovered as determinants for electrically open and short conditions. There have been both numerical illustrations and graphical demonstrations. On the stage speed of the combined RW, the impact of the grooved border, initial pressure, piezoelectric constant, dielectric constant, and thickness of the piezoelectric layer have been studied. Additionally, the analytical solution to the issue is compared to and shown to be in good agreement with the stiffness matrix approach result. This study offers a theoretical foundation for creating and developing piezoelectric composite-based devices. It has been found that the generalized RW velocity declines with the increase of the values of [Formula: see text] and [Formula: see text] and an inverse relationship has been found with the increase of the value of [Formula: see text]. In addition, it has also been noticed that the velocity profile of the generalized RW is greatly influenced by the size of the corrugation (measured at the upper layer).

One-step fabrication of high-performance graphene composites from graphite solution for bio-scaffolds and flexible strain sensors

Graphene composites possess great application potential in various fields including flexible electrodes, wearable sensors and biomedical devices owing to their excellent mechanical and electrical properties. However, it remains challenging to fabricate graphene composites-based devices with high consistency due to the gradual aggression effect of graphene during fabrication process. Herein, we propose a method for one-step fabricating graphene/polymer composite-based devices from graphite/polymer solution by using electrohydrodynamic (EHD) printing with the Weissenberg effect (EPWE). Taylor–Couette flows with high shearing speed were generated to exfoliate high-quality graphene with a rotating steel microneedle coaxially set in a spinneret tube. The effects of the rotating speed of the needle, spinneret size and precursor ingredients on the graphene concentration were discussed. As a proof of concept, EPWE was used to successfully fabricate graphene/polycaprolactone (PCL) bio-scaffolds with good biocompatibility and graphene/thermoplastic polyurethane strain sensor for detecting human motions with a maximum gauge factor more than 2400 from 40% to 50% strain. As such, this method sheds a new light on one-step in situ fabrication of graphene/polymer composite-based devices from graphite solution with low cost.

Simultaneously elevating the resistive switching level and ambient-air-stability of 3D perovskite (TAZ-H)PbBr3-based memory device by encapsulating into polyvinylpyrrolidone

The study about simultaneously enhancing the resistive switching level and ambient-air-stability of perovskite-based memorizers will promote its commercialization. Here, a new 3D perovskite (TAZ-H)PbBr3 (TAZ-H+ = protonated thiazole) has been fabricated as FTO/(TAZ-H)PbBr3/Ag device, which only exhibits binary memory performance with the high tolerant temperature of 170 °C. After encapsulating by polyvinylpyrrolidone (PVP), the (TAZ-H)PbBr3@PVP composite-based device can demonstrate ternary resistive switching behavior with considerable ON2/ON1/OFF ratio (105.9: 103.9:1) and high ternary yield (68 %). Specially, this device presents good ambient-air stability at RH 80 % and thermal tolerance of 100 °C. The binary resistive switching mechanism can be ascribed to the halogen ion migration induced by bromine defects in the (PbBr3)nn– framework. But the ternary resistive switching phenomenon in the (TAZ-H)PbBr3@PVP-based device could be depicted as the carrier transport from filled traps of PVP to (PbBr3)nn– framework (ON1 state) and then carriers flowing in the re-arranged (TAZ-H)nn+ chain in 3D channels (ON2 state). The PVP treatment can not only modify the grain boundary defects, but also facilitate the transport of injected carriers to the perovskite films via Pb-O coordinated bonds and inhibition of order-disorder transformation. This facial strategy for implementing ternary perovskite-based memorizers with good ambient-air-stability is quite meaningful for high-density memory in harsh environments.

Humidity-Tolerant Room-Temperature Selective Dual Sensing and Discrimination of NH3 and NO Using a WS2/MWCNT Composite.

Continuous detection of toxic and hazardous gases like nitric oxide (NO) and ammonia (NH3) is needed for environmental management and noninvasive diagnosis of various diseases. However, to the best of our knowledge, dual detection of these two gases has not been previously reported. To address the challenge, we demonstrate the design and fabrication of low-cost NH3 and NO dual gas sensors using tungsten disulfide/multiwall carbon nanotube (WS2/MWCNT) nanocomposites as sensing channels which maintained their performance in a humid environment. The composite-based device has shown successful dual detection at temperatures down to 18 °C and relative humidity of 90%. For 0.1 ppm ammonia, it exhibited a p-type conduction with response and recovery times of 102 and 261 s, respectively; on the other hand, with NO (10 ppb, n-type), these times were 285 and 198 s, respectively. The device with 5 mg MWCNTs possesses a superior selectivity along with a relative response of ≈7% (5 ppb) and ≈5% (0.1 ppm) for NO and NH3, respectively, at 18 °C. The response is less affected by relative humidity, and this is attributed to the presence of MWCNTs that are hydrophobic in nature. Upon simultaneous exposure to NO (5-10 ppb) and NH3 (0.1-5 ppm), the response was dominated by NO, implying clear discrimination to the simultaneous presence of these two gases. We propose a sensing mechanism based on adsorption/desportion and accompanied charge transfer between the adsorbed gas molecules and sensing surface. The results suggest that an optimized weight ratio of WS2 and MWCNTs could govern favorable sensing conditions for a particular gas molecule.

Improved resistive switching of RGO and SnO2 based resistive memory device for non-volatile memory application

Resistive switching memory, which combines simple architectures with the ability of high density, high switching speed, and low power consumption, has sparked a lot of attention in the field of non-volatile memory devices. In the present work, the resistive switching performance of reduced graphene oxide (RGO) and tin oxide (SnO2) based nanocomposite have been carried out. RGO, SnO2, and RGO-SnO2 nanocomposite were synthesized via hydrothermal technique and the formation of nanocomposite is confirmed by X-ray diffraction and Raman spectroscopy techniques. We herein present a bipolar resistive switching memory based on SnO2 and RGO-SnO2 fabricated by a simple spin-coating process. The two different memory devices have been fabricated by depositing pure SnO2, and RGO-SnO2 films over the bottom ITO electrode and top Al electrodes deposited through a shadow mask. It was observed that devices with RGO-SnO2 showed improved resistive switching in comparison to pure SnO2 film. This improvement of the composite-based film is recognized in terms of switching parameters, such as a reduction in the device operating voltage from 4.11 V for SnO2 to 1 V for RGO-SnO2 composite-based devices. In addition, the resistance ratio in the composite-based films showed significant enhancement. Further, the retention and endurance behavior of the fabricated composite film-based device was tested up to 1 * 103 s and up to 100 cycles respectively which didn’t exhibit any degradation. The operating mechanism of the memory device was explained by fitting the current-voltage characteristics in the low-resistance and high-resistance states. It may be highlighted that the present metal oxide and RGO-based devices have great potential for future non-volatile memory devices.

Soft Composites Filled with Iron Oxide and Graphite Nanoplatelets under Static and Cyclic Strain for Different Industrial Applications.

Simultaneously exhibiting both a magnetic response and piezoelectric energy harvesting in magneto-rheological elastomers (MREs) is a win–win situation in a soft (hardness below 65) composite-based device. In the present work, composites based on iron oxide (Fe2O3) were prepared and exhibited a magnetic response; other composites based on the electrically conductive reinforcing nanofiller, graphite nanoplatelets (GNP), were also prepared and exhibited energy generation. A piezoelectric energy-harvesting device based on composites exhibited an impressive voltage of ~10 V and demonstrated a high durability of 0.5 million cycles. These nanofillers were added in room temperature vulcanized silicone rubber (RTV-SR) and their magnetic response and piezoelectric energy generation were studied both in single and hybrid form. The hybrid composite consisted of 10 per hundred parts of rubber (phr) of Fe2O3 and 10 phr of GNP. The experimental data show that the compressive modulus of the composites was 1.71 MPa (virgin), 2.73 (GNP), 2.65 MPa (Fe2O3), and 3.54 MPa (hybrid). Similarly, the fracture strain of the composites was 89% (virgin), 109% (GNP), 105% (Fe2O3), 133% (hybrid). Moreover, cyclic multi-hysteresis tests show that the hybrid composites exhibiting higher mechanical properties had the shortcoming of showing higher dissipation losses. In the end, this work demonstrates a rubber composite that provides an energy-harvesting device with an impressive voltage, high durability, and MREs with high magnetic sensitivity.

Highly Selective Ethyl Mercaptan Sensing Using a MoSe2/SnO2 Composite at Room Temperature.

Volatile organic sulfur compounds (VOSCs) serve not only as biomarkers for dental diseases such as halitosis but also as a tracer for monitoring air quality. Room-temperature selective detection and superior sensitivity against VOSCs at a sub-ppm level has remained a challenging task. Here, we propose a heterostructure-based design using a MoSe2/SnO2 composite for achieving sensitive and selective detection of ethyl mercaptan at room temperature. The composite was synthesized via a facile two-step method. A composite-based device has shown detection down to 1 ppm of ethyl mercaptan over a wider range of relative humidity (40-90%). Notably, the composite has shown adsorption selectivity toward ethyl mercaptan compared to hydrogen sulfide and other reducing or oxidizing analytes. Moreover, a density functional theory (DFT) study has been performed to understand the adsorption selectivity, charge transfer, and modification in the electronic properties after molecule adsorption on the host surface. Simulations predicted the lowest negative adsorption energy for ethyl mercaptan, implying the chemisorption (-142.029 kJ mol-1) process of adsorption. The device thus-obtained has also shown a stable response even at an extreme relative humidity level of 90%. The obtained results and superior signal-to-noise ratio indicate that a MoSe2/SnO2-based sensor may be a promising candidate for highly selective and sensitive detection of ethyl mercaptan even below 1 ppm.

Fabrication and Characterization of a 5 mm × 5 mm Aluminum Lens-Based Histotripsy Transducer.

Two 5 mm by 5 mm square aluminum lenses with a 6 mm depth of focus were machined and tested for histotripsy with a 40% volume fraction 1-3 PZT-5A composite and a Meggitt Pz-39 porous ceramics lapped to 315 [Formula: see text] as the piezoelectric elements. The devices were air-backed, and an 89 [Formula: see text] layer of Parylene-C was deposited on the lens, matching aluminum to water. Both devices were driven single-ended at 5.8 MHz, their optimal frequency after bonding to the lens, with ten cycles at a PRF of 1 kHz. The composite-based device showed no sign of free-field cavitation in water up to a drive level of 600 V, whereas the Pz39-based device was able to cavitate in water at a drive level of 220 V. In vivo ablation of a rat brain tissue was demonstrated through an opening in the skull and required the drive voltage be increased to 280 V. The ablation was monitored using B-mode imaging with an endoscopic 30 MHz ultrasound phased array and power Doppler overlay. Ablation was maintained for 12 s and, in the power Doppler image, the ablation zone grew steadily over this time to 1.9 mm by 3.4 mm. Immediately after treatment, the ablated area appeared anechoic, slowly filling with specular material.

Highly reliable memristive devices with synaptic behavior via facilitating ion transport of the zeolitic imidazolate framework-8 embedded into a polyvinylpyrrolidone polymer matrix

Composite-based memristive devices have attracted tremendous attention as promising applications in futuristic information technologies due to their synergetic effects between the solid filler and the polymer matrix for enabling versatile information processing. Here, we demonstrate the digital data storing and the analog data processing capabilities of artificial synapses consisting of zeolitic imidazolate framework-8 (ZIF 8):polyvinylpyrrolidone (PVP) hybrid nanocomposites. The composite-based devices exhibited excellent resistive switching behaviors with reliable operating voltage (1.24 ± 0.12 and −2.75 ± 0.33 V) and a large RON/ROFF ratio (7.8 × 103) for 500 repeated resistance switching cycles. The fundamental synaptic behaviors in neuromorphic systems, such as potentiation/depression, transitions from short-term to long-term memory, and the biological learning rules of spiking time-dependent plasticity, were imitated. Finally, via structural and theoretical analyses, we demonstrated that the excellent memristive behaviors were due to the ion trapping effect of the ZIF-8 nanoparticles in the ZIF-8:PVP hybrid composite film.

Kinetic motion sensors based on flexible and lead-free hybrid piezoelectric composite energy harvesters with nanowires-embedded electrodes for detecting articular movements

Self-powered motion sensors have drawn many attentions for the last decade because it can be usefully applied to not only smart clothing and biomedical applications but also future remote controlling robotics systems. In this study, we develop a ceramic–polymer hybrid lead-free piezoelectric composite-based device to fabricate excellent flexible energy harvesters and kinetic motion sensing gloves. With the use of a composite composed of (K,Na)NbO3 (KNN) piezoelectric particles and poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] matrix, the fabricated flexible energy harvester generates an open-circuit voltage of ~5 V and short-circuit current of ~1 μA under mechanical bending deformations. Moreover, the advantages of the P(VDF-TrFE) matrix for piezoelectric composite-based devices are validated by the results of the finite element method (FEM) simulation. Based on the hybrid piezoelectric composite, stable and reliable self-powered kinetic motion sensors are fabricated to monitor tiny biomechanical motions, i.e., the angles of finger hinges and various hand gestures. Our development successfully indicates that the hybrid lead-free piezoelectric composite can be applied to the active component of self-powered kinetic sensors for future low-power electronic motion detector.

Silver-decorated multiwall carbon nanotubes: synthesis characterization and application in polymer composite-based devices

The present work reports a novel synthesis procedure to decorate multiwall carbon nanotubes (MWCNTs) by silver (Ag) nanoparticles (NPs) via silver nitrate (AgNO3) followed by incorporation of these decorated MWCNTs into polymers to form the nanocomposite. The samples of functionalized MWCNTs (FMWCNTs), Ag-decorated MWCNTs (Ag-MWCNTs) and polymer/Ag-MWNCT composites were investigated using various characterization techniques. The field-emission scanning electron microscope (FESEM) image of Ag-MWCTs reveals the uniform distribution of Ag nanoparticles over the surface of MWCNTs. Energy-dispersive X-ray spectroscopy (EDX), elemental mapping, X-ray diffraction (XRD) and Raman spectroscopy confirmed the successful formation of Ag-decorated MWCNTs. FESEM images and UV–Vis absorption spectra of polymer/Ag-MWNCTs composites clearly validates the development of polymer/Ag-MWCNT composites. Finally, the polymer/Ag-MWCNT-based devices were fabricated to compare the electrical performance with those comprising the pristine polymers. The 3D conducting pathways formed by MWCNT and extremely high conductivity of Ag contribute to the improved current levels and reduced cut-in voltage in the Ag-MWCNTs compared to the pristine devices. The electrical transport study also shows a significant modification in the dominant transport mechanism by addition of Ag-MWCNT in the polymer matrix. The present study could pave the path for the development of various cost-effective high-performance electronic devices based on Ag-MWCNT/polymer composites.

NIR light manipulated “paper art” for customizing devices with sophisticated structure from DA-epoxy/graphene composites

Irreversible covalent network in thermosets brings great difficulty to their reprocessing. Especially, customizing devices with sophisticated architecture still remains a challenge. Herein, a novel “paper art” strategy is developed for preparing epoxy-based components or devices with specifically designed structure by introducing dynamic Diels-Alder network and well dispersed Graphene in epoxy matrix. The physical or chemical transitions such as glass transition, reversible dissociation/reconstruction and irreversible dissociation of DA network are spatially and temporally controlled by NIR-triggered in-situ photothermal conversion of GE and therefore served as “folding”, “bonding” and “scissoring”, which are three fundamental operations of “paper art”, respectively. Thus, by setting up the program of these NIR light-manipulated fundamental operations, epoxy resin composite-based devices with designed hierarchical architecture are facilely prepared.

High-Performance and Flexible Shortwave Infrared Photodetectors Using Composites of Rare Earth-Doped Nanoparticles.

The growing demand of infrared sensors for emerging applications such as autonomous vehicles and remote control and sensing systems has driven the development of flexible, low-power, and sensitive infrared detectors for seamless product integration. Although semiconducting polymer (SCP)-based photodetectors are promising solutions, challenges in synthesis chemistry and high thermal dark currents associated with narrowing of band gaps have limited their progress. To address these challenges, we have designed a new class of composites comprising SCPs with moderate band gap and rare earth doped-nanoparticles (RENPs) that enable photon-to-electron conversion beyond the SCP's response range. Using this RENP-SCP (RE-SCP) composite, we demonstrated detection at multiple wavelengths (808, 975, and 1532 nm) for planar-type photodetectors. Notably, the RE-SCP composite-based device detected an eye-safe, shortwave infrared (SWIR) source at 1532 nm with high SWIR responsivity of 0.02 A/W and an SWIR external quantum efficiency of 2%. The key attribute governing the excellent SWIR responsivity and sensitivity was the distinctive SWIR upconversion characteristic of RENPs that extended and improved the SCP's detection range and performance, respectively. Additionally, the absence of significant performance degradation of the SWIR photodetector for bending curvatures from 0-0.67 cm-1 highlights the promise of our RE-SCP composite-based flexible SWIR photodetectors.

Efficient Energy Harvesting in SnO2-Based Dye-Sensitized Solar Cells Utilizing Nano-Amassed Mesoporous Zinc Oxide Hollow Microspheres as Synergy Boosters.

Finding the material characteristics satisfying most of the photovoltaic conditions is difficult. In contrast, utilization of foreign materials that can contribute to light harvesting and charge transfers in the devices is now desirable/thought-provoking. Herein, a binary hybrid photoanode utilizing nano-amassed micron-sized mesoporous zinc oxide hollow spheres (meso-ZnO HS) in conjunction with SnO2 nanoparticles (NPs), i.e., SnO2 NP_ZnO HS (for an optimized weight ratio (8:2)), displayed a nearly ∼4-fold increase in the efficiency (η) compared to that of bare SnO2 nanoparticle device. Enhanced device efficacy in the composite photoanode-based device can be accredited to the dual function of nano-amassed meso-ZnO HS. Nano-amassed micron-sized ZnO HS embedded in the photoanode can increase the light-harnessing capability without sacrificing the surface area as well as optical confinement of light by multiple reflections within its cavity and enhanced light-scattering effects. Electrochemical impedance spectroscopy analysis revealed an extended lifetime of electron (τe) and a higher value of Rct2 at the working electrode/dye/redox mediator interface, indicating a minimum photoinduced electron interception. The open-circuit voltage decay reveals a slower recombination kinetics of photogenerated electrons, supporting our claim that the nano-ammased meso-ZnO HS can serve as an energy barrier to the photoinjected electrons to retard the back-transfer to the electrolyte. Moreover, the improvement in the fill factors of the composite-based devices is endorsed to the facile penetration of the electrolyte through the pores of nano-amassed meso-ZnO HS, which increases the regeneration probability of oxidized dyes.