Self-powered Performance Research Articles

Multi-touch microcapsules/silicone-polyacrylate hybrid hydrogels with precise self-healing ability and their self-powered sensing applications in emergency rescue

Hydrogels offer significant potential for use in wearable soft electronic devices. However, their application faces considerable challenges in outdoor emergencies or extreme environments where a power supply is unavailable. In this study, multi-touch microcapsules with phase change properties were prepared by coating nanogold through silica as Pickering particles. Subsequently, the microspheres were integrated into a silicone oil-modified polyacrylate hydrogel with self-healing capabilities, resulting in the fabrication of a hydrogel strain sensor that exhibits precise self-healing and self-powered functionality. The mechanical properties of the hydrogel sensor can be modified by adjusting the polymer composition. Due to the multi-contact structure of nano-gold on the surface of microcapsules and the dynamic boronic ester bond interaction, the hydrogel sensor possesses precision self-healing capability. In addition, the hydrogel sensors demonstrate high sensitivity, which can accurately detect some subtle human motions, such as joint flexion. Importantly, the synthesized composite hydrogel exhibits self-powered performance, which could be helpful for rescue operations in outdoor or extreme environments. This study provides helpful results that can be used in the development of wearable soft electronics based on conductive hydrogels.

All-Layer Electrodeposition of a CdTe/Hg0.1Cd0.9Te/CdTe Photodetector for Short- and Mid-Wavelength Infrared Detection

CdS, CdTe, Hg0.1Cd0.9Te, CdTe, and Ag films were progressively electrodeposited on ITO-coated soda–lime glass to manufacture a short- and mid-wavelength infrared photodetector. A distinctive feature of the applied electrodeposition method is the use of a non-aqueous solution containing ethylene glycol (EG) as the electrolyte in a traditional three-electrode configuration for every film deposition. Using EG as a supplementary electrolyte and using the same deposition conditions with a potential below 0.75 V for all film coatings reduces their environmental incompatibility and offers a low-cost and low-energy route for fabricating the reported photodetector. The produced photodetector has a sensitivity of up to ≈957 nm with a detectivity (D*) of 2.86 × 1012 cm Hz1/2 W−1 and a dark current density (Jdark) of 10−6 mA cm−2. Furthermore, the manufactured photodiode exhibits self-powered performance because Voc and Jsc are self-generated, unlike previously reported photodiodes. The presented all-layer electrodeposition assembly approach can easily be adapted to fabricate sensing devices for different applications.

Strain sensors enhanced by a flexible, conductive hydrogel with superior transparency, frost resistance, and water retention

Flexible hydrogels have received significant attention for their excellent mechanical properties, fast response and good strain sensitivity. However, relatively little research has been conducted on the investigation of hydrogels that exhibit frost resistance, water retention, and transparency characteristics. In this paper, a new flexible strain sensors material was prepared by introducing calcium chloride (CaCl2) and hydrolysed keratin (HK) into the polyvinyl alcohol (PVA) system through complex chemical bond. The PVA/CaCl2/HK hydrogel exhibited excellent mechanical properties, with a tensile strength of 1.578 MPa and a maximum strain of 934 %. Moreover, it showed high transparency, with a transmittance of up to 90 %. The hydrogel demonstrated remarkable water retention properties with about 8 hours of dry resistance under constant temperatures of 40 °C, 60 °C, 80 °C and 100 °C. Additionally, it had excellent frost resistance with a glass transition temperature of −23 °C, making it environmentally tolerant and capable of maintaining long-term stability. Notably, during the experiment, the PVA/CaCl2/HK hydrogel exhibited excellent electrical conductivity and self-powered performance, with a power supply capacity of approximately 14.6 mV. The results of this work provide a promising direction for the development of electronic materials for powered hydrogel strain sensors.

Accelerated Wound Healing by Electrospun Multifunctional Fibers with Self-Powered Performance.

Wound healing has been a persistent clinical challenge for a long time. Electrical stimulation is an effective therapy with the potential to accelerate wound healing. In this work, the self-powered electrospun nanofiber membranes (triples) were constructed as multifunctional wound dressings with electrical stimulation and biochemical capabilities. Triple was composed of a hydrolyzable inner layer with antiseptic and hemostatic chitosan, a hydrophilic core layer loaded with conductive AgNWs, and a hydrophobic outer layer fabricated by self-powered PVDF. Triple exhibited presentable wettability and acceptable moisture permeability. Electrical performance tests indicated that triple can transmit electrical signals formed by the piezoelectric effect to the wound. High antibacterial activities were observed for triple against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, with inhibition rates of 96.52, 98.63, and 97.26%, respectively. In vitro cell assays demonstrated that triple cells showed satisfactory proliferation and mobility. A whole blood clotting test showed that triple can enhance hemostasis. The innovative self-powered multifunctional fibers presented in this work offer a promising approach to addressing complications and expediting the promotion of chronic wound healing.

Artificial intelligence motivated flexible single-electrode mode multilayer triboelectric sensor for smart mobility systems

Triboelectric tactile sensing technique is increasingly coming into people’s lives to bring convenience, so that there is an urgent necessity for this technique to be applied to smart mobility to increase safety and enhance the mobility experience. Herein, a single-electrode mode multilayer triboelectric sensor (MTS) motivated by artificial intelligence (AI) is proposed, which consists of styrene-butadiene-styrene (SBS)/ poly (vinylida-ene fluoride-trifluoroethylene) (PVDF-TrFE) nanofibers (NFs) film as the friction layer and substrate, laser-induced graphene (LIG)/molybdenum disulfide (MoS2) as the charge trapping layer, and Ag as the electrode. The MTS exhibits remarkable sensing performance, such as a wide response range of 5–100 N, 0.4–2 Hz multi-frequency response capability, and non-contact sensing, as well as distinguished self-powered performance. To demonstrate the practical significance of the proposed MTS, two applications are explored specifically after equipping with AI, including: (i) a smart in-vehicle system is constructed, which consists of unlocking section and multifunctional control with early warning section. (ii) a smart car control system is implemented, which can carry out special tasks instead of humans. These applications provide reliable ways to promote the development of human-machine interaction and smart mobility, as well as help to make lifestyles and mobility smarter, safer and more convenient.

Self-powered deep ultraviolet photodetector based on p-CuI/n-ZnGa2O4 heterojunction with high sensitivity and fast speed.

Self-powered deep ultraviolet photodetectors (DUV PDs) are essential in environmental monitoring, flame detection, missile guidance, aerospace, and other fields. A heterojunction photodetector based on p-CuI/n-ZnGa2O4 has been fabricated by pulsed laser deposition combined with vacuum thermal evaporation. Under 260 nm DUV light irradiation, the photodetector exhibits apparent self-powered performance with a maximum responsivity and specific detectivity of 2.75 mA/W and 1.10 × 1011 Jones at 0 V. The photodetector exhibits high repeatability and stability under 260 nm periodic illumination. The response and recovery time are 205 ms and 133 ms, respectively. This work provides an effective strategy for fabricating high-performance self-powered DUV photodetectors.

Efficient and stable self-powered PbSe photodetectors via doping-induced asymmetric Cr electrodes modulation of surface work function

Conventional PbSe infrared photodetectors typically demands a substantial external electric field, posing challenges in energy-constrained environments. Self-powered photodetectors present a promising avenue for addressing such electricity-related challenges. Nevertheless, the inherent limitations of symmetric Schottky contacts in metal-semiconductor-metal (MSM) photodetectors constrain their self-powered performance, resulting in opposing photocurrents. Constructing asymmetric MSM structures usually requires intricate design or sustained external fields. In this study, we propose a novel contact engineering strategy based on iodine doping to modulate surface work functions of PbSe film. Utilizing Cr electrodes, we achieve Ohmic contact on the iodine-doped top surface of PbSe film and Schottky contact on the as-grown bottom surface. This approach establishes a self-powered PbSe infrared photodetector with an asymmetric top-bottom MSM structure. We comprehensively investigate contact engineering by investigating surface chemical states, elemental variations, and surface work functions variation. Remarkably, the photodetector demonstrates an exceptional zero-bias detectivity of 1.13 × 109 Jones, with an extremely low dark current of 3.67 pA, high Ilight/Idark ratio exceeding 104, and extremely short response times of less than 1 ms, respectively. Our work introduces a new strategy for modifying the band structure, contributing to the fabrication of high-performance self-powered photodetectors.

Tough, Antifreezing, and Piezoelectric Organohydrogel as a Flexible Wearable Sensor for Human-Machine Interaction.

Piezoelectric hydrogel sensors are becoming increasingly popular for wearable sensing applications due to their high sensitivity, self-powered performance, and simple preparation process. However, conventional piezoelectric hydrogels lack antifreezing properties and are thus confronted with the liability of rupture in low temperatures owing to the use of water as the dispersion medium. Herein, a kind of piezoelectric organohydrogel that integrates piezoelectricity, low-temperature tolerance, mechanical robustness, and stable electrical performance is reported by using poly(vinylidene fluoride) (PVDF), acrylonitrile (AN), acrylamide (AAm), p-styrenesulfonate (NaSS), glycerol, and zinc chloride. In detail, the dipolar interaction of the PVDF chain with the PAN chain facilitates the crystal phase transition of PVDF from the α to β phase, which endows the organohydrogels with a high piezoelectric constant d33 of 35 pC/N. In addition, the organohydrogels are highly ductile and can withstand significant tensile and compressive forces through the synergy of the dipolar interaction and amide hydrogen bonding. Besides, by incorporating glycerol and zinc chloride, the growth of ice crystals is inhibited, allowing the organohydrogels to maintain stable flexibility and sensitivity even at -20 °C. The real-time monitoring of the pulse signal for up to 2 min indicates that the gel sensor has stable sensitivity. It is believed that our organohydrogels will have good prospects in future wearable electronics.

High-responsivity self-powered deep-ultraviolet photodetector based on n-SnS2/p-GaN heterostructures

Deep-ultraviolet (DUV) photodetectors (PDs) have important applications in various fields, however, high manufacturing costs, complex fabrication processes, and high-power consumption limit their further development. Here, the combination of physical vapor deposition (PVD) and chemical vapor deposition (CVD) methods are used to grow in-situ vertical SnS2 (v-SnS2) thin film on a gallium nitride (GaN) substrate, thereby forming a v-SnS2/GaN p-n heterojunction (type-Ⅱ). With zero bias, the device exhibits excellent self-powered performance under 265 nm illumination. The sensor has a large responsivity of 3.525 A/W, a high specific detectivity of 1.767 × 1014 Jones, a high linear dynamic range of 97 dB, and a fast response speed (rise/decay time of 150.5/266.4 µs). This work demonstrates the great potential of SnS2/GaN heterojunction devices for deep-ultraviolet detection.

Self-powered CdS nanorods/planar-Si photodetector and its performance optimization by fully developing pyro-phototronic effect

Self-powered performance is a crucial aspect of photodetectors (PDs) as it allows them to function without the need for external power sources. PDs with excellent broadband self-powered property are dependable, cost-effective, and possess high-efficiency photoelectric conversion, making them suitable for various applications. In this manuscript, a simple and low-cost hydrothermal synthesis method is employed to directly deposit cadmium sulfide (CdS) nanorods onto planar silicon (Si) substrate, resulting in a self-powered PD that incorporates a n-CdS nanorods/p-Si heterostructure. Outstanding photoresponses are observed for the PD in the range of 405∼1064 nm and open circuit voltages (Vocs) are significant, proving its prominent broadband self-powered performance. The maximum responsivity (R) and detectivity (D) are 3.92 mA/W and 7.91 × 108 Jones at zero bias, respectively. Besides, as the CdS nanorods grown on the planar Si surface exhibit superior c-axis orientation, the pyroelectric field caused by temperature variation could significantly enhance carrier transport and separation behavior in the heterojunction. Therefore, the optimal R of 64.8 mA/W and D of 1.31 × 1010 Jones are achieved, with an argument of 3450.5%, as well as a fast response time of 190.8/298.4 μs. Furthermore, the light response wavelength extends to 1550 nm, covering visible light to near-infrared, far beyond the spectral limitations of the heterojunction. This high-performance broadband self-powered PD is expected to show great potentials in various applications.

Ultrafast self-powered phototransistor based on Te-WSe2 van der Waals heterojunction

Band engineering through the integration of van der Waals heterostructures composed of 2D materials offers a promising approach to achieving high-performance optoelectronic devices. This strategy allows for the fabrication of ultrathin and uniform PN junctions with well-defined band edges, enabling efficient charge transfer and separation. In this study, we have developed a self-powered and highly sensitive photodetector using a van der Waals heterostructure composed of WSe2 and Te. The Te layer was employed as the channel material for the phototransistor, while the out-of-plane Te/WSe2 PN junction served as the charge transfer layer. The vertical built-in electric field present in the PN junction facilitated the separation of photogenerated carriers. The proposed phototransistor demonstrated exceptional self-powered performance characteristics, including a photoresponsivity of 33.08 mA/W, a specific detectivity of 1.57 × 106 Jones, and a fast response time of 2 μs. These results highlight the effectiveness of the van der Waals heterostructure design in achieving high sensitivity and efficient carrier separation in photodetection applications.

Two-dimensional perovskite Pb2Nb3O10 photodetectors

For the first time, we report high-performance two-dimensional (2D) perovskite Pb2Nb3O10 photodetectors (PNO PDs). The few-layer PNO nanosheets are obtained successfully through a simple calcination and liquid exfoliation method. The individual PNO nanosheet devices with various structures (Au-PNO-Au, Au-PNO-Ti, Ti-PNO-Ti) are fabricated and investigated. The Au-PNO-Ti device exhibits a high rectification factor (∼102) owing to a large Schottky barrier difference between the PNO nanosheet and two asymmetric electrodes. Notably, the Au-PNO-Ti device shows excellent self-powered performance, including high responsivity (2.8 A/W), high detectivity (1.1 × 1012 Jones), and fast speed (0.2/1.2 ms) at 350 nm light illumination. This work not only suggests the performance of the PNO nanosheet PDs but also sheds light on the development of high-stability and high-performance devices based on 2D perovskite niobate in the future.

Hybrid PEDOT:PSS/SiC heterojunction UV photodetector with superior self-powered responsivity over A/W level

In this Letter, an ultraviolet photodetector constructed on a simple vertical PEDOT:PSS/SiC hybrid heterojunction with superior self-powered performance was reported. Benefitting from the abundant charge carrier concentration in 4H-SiC substrate and the large built-in field at PEDOT:PSS/SiC heterointerface, the SiC based photodetector (PD) realized self-powered responsivity over A/W level, even comparable with many reported 4H-SiC avalanche photodiodes. Upon illumination with deep-UV wavelength at 254 nm, the responsivity, detectivity, and external quantum efficiency of the fabricated PD reached up to 2.15 A/W, 1.9 × 1013 Jones, and 1053%, respectively. Furthermore, the rise/decay time was as fast as 58.6/41.5 ms, the on–off switching ratio was as large as 8.73 × 103, the spectral rejection ratio (R254/R390) was as high as 4.3 × 103, and the lifetime reliability was over 195 days. Serving as a sensing pixel, the designed heterojunction PD demonstrated excellent imaging capability in homemade UV imaging system, showing promising applications in future energy-conservation photoelectronic system.

A novel switch control scheme for concise S–SSHI array interface with multiple piezoelectric energy harvesters

Energy harvesting array formed by multiple piezoelectric transducers (PZTs) can concurrently supply power to the load to improve the reliability. However, the switch control scheme adopted by the existing extensible parallel/series synchronized switch harvesting on inductor interfaces use either dual inductors or redundant peak detectors, both increasing the volume of the circuits. Hence, a novel switch control scheme using RC differential circuit (SCS-RCD) to simplify circuits for multiple piezoelectric harvesters is proposed in this article. It is implemented by reducing the number of switches required for the single piezoelectric block and improving the reuse of components. Extensible S–SSHI (ES-SSHI) circuit based on the SCS-RCD scheme with self-powered performance is proposed. Both theoretical simulation and experimental test demonstrate the effectiveness of the proposed SCS-RCD. The maximum harvested power of prototyped ES-SSHI circuit for single PZT is 3.76 times that of SEH circuit. The results show that the proposed scheme is an alternative option for multiple piezoelectric inputs.

Phase‐Modulated Multidimensional Perovskites for High‐Sensitivity Self‐Powered UV Photodetectors

2D Ruddlesden-Popper perovskites (PVKs) have recently shown overwhelming potential in various optoelectronic devices on account of enhanced stability to their 3D counterparts. So far, regulating the phase distribution and orientation of 2D perovskite thin films remains challenging to achieve efficient charge transport. This work elucidates the balance struck between sufficient gradient sedimentation of perovskite colloids and less formation of small-n phases, which results in the layered alignment of phase compositions and thus in enhanced photoresponse. The solvent engineering strategy, together with the introduction of poly(3,4-ethylene-dioxythiophene):polystyrene sulfonate (PEDOT:PSS) and PC71 BM layer jointly contribute to outstanding self-powered performance of indium tin oxide/PEDOT:PSS/PVK/PC71 BM/Ag device, with a photocurrent of 18.4µA and an on/off ratio up to 2800. The as-fabricated photodetector exhibits high sensitivity characteristics with the peak responsivity of 0.22AW-1 and the detectivity up to 1.3×1012 Jones detected at UV-A region, outperforming most reported perovskite-based UV photodetectors and maintaining high stability over a wide spectrum ranging from UV to visible region. This discovery supplies deep insights into the control of ordered phases and crystallinity in quasi-2D perovskite films for high-performance optoelectronic devices.

High ionic thermopower in flexible composite hydrogel for wearable self-powered sensor

Ionic-conductive hydrogel sensors are widely used in wearable electronics, and biomedical monitoring. Meanwhile, the hydrogel can use the heat continuously released from human body to generate thermal voltage by relying on the thermal diffusion effect and achieving thermoelectric conversion. It is the most effective solution to realize self-powered supply obtaining energy from environmental waste heat. However, the low thermoelectric output power of hydrogel restricts their applications. Herein, a highly flexible composite hydrogel with ultrahigh thermoelectric output power is designed, wherein hydrogel containing NaCl is prepared by radical polymerization and metal ion complexation, in which the CaCl2 provide the second crosslinking network. Consequently, the optimized hydrogel has excellent stretchability and can withstand up to 1500% tension. The sensitivity of the hydrogel sensor is up to 7.01 in the range of 600%–1500%, which has excellent stability and reversibility. Furthermore, the fast response time of the hydrogel sensor was 12.8 ms. The ionic thermovoltage and power density observed in this study are 34.27 mV K−1 and 730 mW m−2, respectively. The results demonstrated that the ionic-conductive hydrogels with excellent ionic thermovoltage and the ultrahigh power density may be a potential candidate to realize the self-powered performance of hydrogel wearable sensor.

Light-Tunable Polarity and Erasable Physisorption-Induced Memory Effect in Vertically Stacked InSe/SnS2 Self-Powered Photodetector.

van der Waals heterojunctions with tunable polarity are being actively explored for more Moore and more-than-Moore device applications, as they can greatly simplify circuit design. However, inadequate control over the multifunctional operational states is still a challenge in their development. Here, we show that a vertically stacked InSe/SnS2 van der Waals heterojunction exhibits type-II band alignment, and its polarity can be tuned by an external electric field and by the wavelength and intensity of an illuminated light source. Moreover, such SnS2/InSe diodes are self-powered broadband photodetectors with good performance. The self-powered performance can be further enhanced significantly with gas adsorption, and the device can be quickly restored to the state before gas injection using a gate voltage pulse. Our results suggest a way to achieve and design multiple functions in a single device with multifield coupling of light, electrical field, gas, or other external stimulants.

Annealing temperature effect on the performances of porous ZnO nanosheet-based self-powered UV photodetectors.

Porous ZnO nanosheets (ZnO NSs) may play an important role in self-powered UV photodetectors due to their excellent properties, and their porosity feature affects the photoresponse performance greatly. Porous ZnO NSs were prepared by the hydrothermal method followed with a one-step annealing treatment. The effects of the annealing temperature on the microstructure and photoresponse of porous ZnO NSs and n-ZnO NSs/p-PEDOT:PSS self-powered UV photodetectors were investigated. The results show that the pore density and size of ZnO NSs can be tuned by changing the annealing temperature. At an optimum annealing temperature of 450°C, ZnO NSs exhibit greater absorption capacity for the suitable pore density and size. Meanwhile, more crystal defects due to surface contractile properties increase the number of photogenerated carriers. On this basis, the n-ZnO NSs/p-PEDOT:PSS photodetector presents a larger photocurrent and fast photodetection speed without external bias voltage, indicating the self-powered performance. The higher light absorption and large number of electron-hole pairs resulting from dense pores and surface defects in porous ZnO NSs might account for the enhanced performances.

High-performance Ag2BiI5 Pb-free perovskite photodetector

Recently, lead-free all-inorganic halide perovskites have attracted great interest because they not only have the merits of the halide perovskite family, but also are non-toxic. However, the commercialization of lead-free all-inorganic perovskites is restricted by their relatively low performances, which are usually caused by the fabrication methods and undesirable interfaces between the active layer and carrier transport layers. Herein, we demonstrate a solution-processed route for high-quality Ag 2 BiI 5 lead-free perovskite film by adopting ideal electron transport material SnO 2 and a carbon electrode. By optimizing the fabrication process and tailoring the composition of the perovskite active layer, a high-performance photodetector (PD) with an FTO / SnO 2 / Ag 2 BiI 5 / carbon structure PD is first fabricated, which shows good self-powered performance with a detectivity of as high as 5.3 × 10 12 Jones and a linear dynamic range of up to 138 dB, which are better than those of the reported Pb-free perovskite PDs and comparable to high-performance Pb-based perovskite PDs. In addition, our unpackaged PDs show good light, thermal, and storage stability in air. Our results provide a special route for the development of lead-free perovskite devices in an environmentally friendly field.

High-performance self-powered ultraviolet photodetector based on PEDOT:PSS/CuO/ZnO nanorod array sandwich structure

This study reports a sensitive self-powered ultraviolet photodetector (UV PD) fabricated with a facile cost-effective hydrothermal and RF magnetron sputtering combination method. The obtained PD is in sandwich configuration based on p-n junction, consisting of ZnO nanoarray bottom n-layer, poly (3, 4 ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) top p-layer, and CuO insertion layer. The developed PD shows superior self-powered performance with responsivity of 9.96 mA/W under weak UV illumination (365 nm, 0.4 mW/cm2) and good wavelength selectivity (R365nm/R400nm = 4.87 × 102). It is found that the CuO insertion layer plays a vital role in the device performance, proving by the fact that the responsivity of the PD with the interlayer is almost 12 times that of the device without. This can be ascribed to the CuO thin layer which improves the junction quality by reducing the recombination centers for carriers, widening the depletion region and providing stepping energy levels between the band edges of ZnO and PEDOT:PSS, and thereby improves overall collection of the photo-generated carriers, leading to much improved photoresponse. The obtained PD also exhibits great multi-cycle stability. This efficient self-powered UV PD along with its cost-effective fabrication process is promising in UV sensor applications.