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In this work, a facile and low-cost method is introduced to boost performance of TiO2-based UV photodetector (PD). The method involves addition of a solution-processed GQDs-CsPbBr3 composite layer to the TiO2 film to fabricate a high-performance and stable hybrid photodetector based on TiO2/GQDs-CsPbBr3 bilayer heterojunction. The TiO2/GQDs-CsPbBr3 bilayer heterojunction was characterized with several techniques. The ultraviolet–visible (UV–Vis) and photoluminescence (PL) spectrometers reveal that the absorption and emission of the TiO2/GQDs-CsPbBr3 bilayer heterojunction have significantly enhanced compared with that of the anatase TiO2 film, without the GQDs-CsPbBr3 composite layer. In addition, The hybrid photodetector shows a low dark current (ID = 0.13 nA), a high light current (IL = 343,626 nA), an on/off ratio (2.69 × 106), a responsivity (R = 7.11 A/W), and a specific detectivity (D* = 3.32 × 1013 J). The responsivity of the hybrid was improved by 64 times in magnitudes compared with that of the TiO2 without the GQDs-CsPbBr3 composite layer. Moreover, the performance of the hybrid photodetector not only outdo the performance of reported PDs based on wide bandgap materials/perovskite and 2D materials/2D materials bilayer heterostructure, but also performance of PDs based on 2D materials/2D materials/2D materials and silicon/2D materials/2D materials triple-layer heterostructure. The enhanced performance of the hybrid PD was due to the excellent alignment between the anatase TiO2, GQDs, and CsPbBr3, which enabled the TiO2/GQDs-CsPbBr3 bilayer heterojunction to reduce recombination process and increase photon-absorption rate. These results pave the way for enhancing the wide bandgap materials-based UV optoelectronics with the solution-processed and low-cost GQDs-CsPbBr3 composite.

In this work, a self-powered and high-performance vertical type photodetector based on solution-processed nitrogen-doped graphene quantum dots and all-inorganic perovskite nanocrystals heterostructure is achieved. The vertical type NGQDs/CsPbBr3 heterojunction photodetector was fabricated using two steps of standard lithography process and drop-casting method. The vertical type NGQDs/CsPbBr3 photodetector (VTPD) exhibited a nonlinear I–V curve with an extremely low dark current of 0.38 nA and 0.29 nA at forward and reverse bias voltage of 3 V, and − 3 V, respectively. Moreover, the vertical type NGQDs/CsPbBr3 photodetector exhibited superior figure of merits (high-performance) with a light current (257.71 nA), an on/off ratio (670), responsivity (R = 3.21 A/W), specific detectivity (D* = 2.9 × 1012 J), and an external quantum efficiency (EQE = 270%) under illumination of light source with a wavelength of 520 nm and power intensity of 0.8 mW/cm2 at bias voltage of 3 V. In addition, the vertical type NGQDs/CsPbBr3 photodetector is confirmed to operate without an external bias voltage demonstrating the obvious photovoltaic characteristics of the device at 0 V. The performance of vertical type NGQDs/CsPbBr3 photodetector (VTPD) is not only surpass the performance of planar type NGQDs/CsPbBr3 photodetector (PTPD) fabricated in this work but also the performance of recently reported self-powered PDs based on carbon/perovskite, and perovskite/perovskite heterostructure. These results pave the way for exploiting solution-processed NGQDs/CsPbBr3 heterojunction to fabricate low-cost, self-powered, and high-performance optoelectronics such as solar cells, light emitting diodes, lasers, and photodetectors.

Elastic conductors play a crucial role in the fabrication of wearable electronic devices and human–computer interaction devices. Among the various candidates for elastic conductors, hydrogels, featuring 3-D swollen macromolecular networks, exhibit exceptional stretchability and biocompatibility. Notably, physical hydrogels based on poly (vinyl alcohol) (PVA), which contains a substantial number of reactive groups (-OH groups), stand out due to their remarkable biocompatibility, superior mechanical properties, and chemical stability. This review focuses on recent advancements in the composite strategy, preparation, and current applications of PVA-based conductive composite hydrogels. Firstly, PVA-based conductive hydrogels are classified based on various conductive treatments: (i) introduction of conductive fillers to the PVA with a single network structure; (ii) introduction of conductive fillers to the PVA with double/multiple network structures (e.g., PVA/carboxymethylcellulose, PVA/poly(acrylamide)); (iii) creation of double-network PVA hydrogel combined with conductive polymers including poly(3,4-ethylene-dioxythiophene)/poly(styrenesulfonate), poly(aniline), poly(pyrrole); (iv) addition of ions to a pure PVA network; (v) addition of ions to the PVA with double network structures (e.g., PVA/sodium alginate, PVA/hydroxyethylcellulose). This review includes a comparative analysis of different conductive hydrogel systems. Secondly, PVA-based conductive hydrogels with diverse functions, such as strain sensing, shape memory, antifreeze properties, transparency, and pH response, are thoroughly reviewed. Thirdly, the latest advancements in the applications of PVA-based conductive hydrogels are demonstrated, including flexible super-capacitors, human–computer interaction devices, and triboelectric nanogenerator sensors. Finally, a summary of the current state of development and critical issues with PVA conductive hydrogels is provided, along with an outlook on how to address each.Graphical AbstractSystematic review on PVA conductive hydrogels: outlines preparation strategies and applications in flexible electronic devices.

A high-performance and stable hybrid photodetector (PD) based on a monolayer MoS2/NH2 GQDs/CsPbBr3 triple junction is demonstrated in this work. The NH2 GQDs was introduced between the monolayer MoS2 and CsPbBr3 to enhance carrier transport and separation process, and optical absorption in the triple junction. The MoS2/NH2 GQDs/CsPbBr3 triple junction was characterized with several techniques. The ultraviolet–visible (UV–vis) and photoluminescence (PL) spectrometers reveal that the absorption and emission of the triple junction have significantly enhanced compared with that of the MoS2/CsPbBr3 bilayer junction, without the NH2 GQDs. In addition, the temperature-dependent photoluminescence (TDPL) confirms that the generated excitons in the hybrid triple structure tend to separate more easily during the device operation process. The hybrid photodetector shows a responsivity (R = 9.39 A/W), specific detectivity (D* = 3.32 × 1012 J), and external quantum efficiency (EQE = 791%). Moreover, the performance of the hybrid photodetector not only outdo the performance of reported PDs based on 2D material (2DM)/perovskite and 2DM/2DM bilayer heterostructure, but also performance of PDs based on 2DM/2DM/2DM and silicon/2DM/2DM triple layer heterostructure. The enhanced performance of the hybrid PD was due to the excellent alignment between the MoS2, NH2 GQDs, and CsPbBr3, which enabled the triple junction to reduce recombination process and increase photon-absorption rate. These results pave the way for incorporating the NH2 GQDs with 2DM and perovskite to fabricate low-cost and high-performance optoelectronics.

Solar cells based on a three-dimensional (3D) crystalline perovskite framework exhibit desired photoconversion efficiency. However, 3D perovskites are prone to surface defects, leading to severe Shockley–Read–Hall (SRH) recombination and insufficient interactions between components, resulting in lower efficiency and stability. In contrast, two-dimensional (2D) perovskites have comparatively better excellent stability in hot and humid environments but suffer from lower efficiency. Recently, researchers reported that surface passivation of 3D perovskite by 2D perovskite improves the stability of solar cells without compromising their efficiency. In this review, the recent advances in surface modification of three-dimensional perovskites using two-dimensional perovskites are discussed. The crystal structures, photoelectric properties, and surface passivation strategies of 2D/3D perovskite solar cells with different components are systematically presented. Finally, the prospect of using two-dimensional perovskite passivation technology to further improve photovoltaic performance is discussed.

The signal crosstalk and electromagnetic interference (EMI) problems direly need to be resolved in the rapid development of modern microwave communication technology for a better working frequency and transmission power of electronic systems. Where the new absorbing materials such as molybdenum disulfide (MoS2)/titania (TiO2)/Ti2CTx and MoS2/Ti2CTx composites could meet the requirement of “thin, strong, light weight, and wide band” for excellent absorbing performance. In this work, a lighter Ti2CTx material was selected as the matrix, and MoS2 was in-situ grown on Ti2CTx matrix by traditional hydrothermal method and microwave solvothermal method. The fabricated composite exhibited synergic effect of two-dimensional heterostructural interface and double dielectric elements, where a small amount of TiO2 and a certain proportion of MoS2 jointly improve the impedance matching of the composite material. In here, the extreme reflection loss (RLmin) can reach − 54.70 dB (with a frequency of 7.59 GHz, 3.39 mm thickness), and the maximum effective absorption bandwidth (EABmax) can reach 4 GHz. Polyethylene glycol 200 was used as the solvent instead of water to make Ti2CTx less oxidized during the composite process, where the microwave heating would attain fast speed, short time, high efficiency, and uniform product. Since, the MoS2/Ti2CTx composite without oxidizing possessed a wider effective absorption bandwidth (EAB) at a thinner thickness, thus resulting in the excellent microwave absorption performance and confirming the validity and rationality of new microwave absorption materials.

To improve the toughness and strength of C/C-SiC composites, carbon fiber reinforced carbon, silicon carbide, and copper alloy hybrid composite were designed and prepared via Cu-Si alloy melt infiltration at low temperature. The as-prepared composite was mainly composed of C, SiC, Cu3Si, and Si phases. Due to the introduction of ductile Cu alloy in the matrix, the composite exhibited good mechanical properties, especially fracture toughness. Cu reacted with Si to produce the Cu3Si phase in the composite’s matrix, which reduced the residual silicon in the normal C/C-SiC composite. The bending strength of the as-prepared composite reached about 258.75 MPa and the fracture toughness was up to about 13.55 MPa·m1/2. The improved toughness of the as-prepared composite was mainly attributed to the introduction of soft Cu3Si phase.

The combustion behavior of ammonium perchlorate (AP) determines the combustion performance of the propellant to a certain extent. Not only the addition of catalyst can change the thermal decomposition performance of AP, but also the combination mode of catalyst and AP can change the thermal decomposition behavior of AP. In this study, different catalysts and AP were prepared by mechanical mixing and spray drying composite, respectively. The results showed that compared with mechanical mixing, spray drying composites showed better catalytic performance on the thermal decomposition of AP. Compared with pure AP, all catalysts passivated the low-temperature decomposition process of AP, while catalyzed the high-temperature decomposition process of AP. At the heating rate of 5 K/min, AP@GO/Cu-MOF-300 makes the high temperature decomposition temperature of AP advance by 105.49 ℃, the activation energy decreases from 194.66 to 101.51 kJ/mol, and the heat release increases nearly four times.

The development of modern infrared detection technology has increased the possibility that military targets will be identified. Therefore, the task of protecting these targets is urgent extremely. The infrared stealth materials should be versatile to achieve the performance requirements of different applications and should be sustainable to achieve environmental friendliness. In order to solve this problem, an antimony doped tin oxide/silver/bamboo fibers (ATO-Ag-BFs) composite bamboo fabrics with multi-functional properties including infrared protection and antibacterial and hydrophobic properties were developed by the combination of ATO loading, chemical deposition, and hot press process. The ATO-Ag-BFs fabrics possessed plasmon resonance absorption properties of near-infrared light, which was attributed to the formation of Schottky junction by direct contact between Ag and ATO nanoparticles. The resulting ATO-Ag-BFs shows the infrared emissivity as low as 0.68 in the 8–14 μm thermal imaging band, which allowed the target to be blended adequately into environmental background. In addition, ATO-Ag-BFs treated with n-hexadecyl mercaptan exhibited remarkable hydrophobic properties with a water contact angle (WCA) of 147.7° compared to the non-hydrophobic treated ATO-Ag-BFs, which increased by 273.9%. Especially, the combination of Ag and ATO nanoparticles endowed bamboo fiber fabrics with outstanding antibacterial properties, with 100% inhibition of both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Overall, the multi-functional ATO-Ag-BFs based on bamboo fibers developed in this study can be applied in the field of wearable infrared and thermal radiation shielding to meet the requirements for concealment in harsh environments, proving that it is a tremendous potential candidate for infrared stealth materials.Graphical Abstract

Interfacial interaction enhancement between biodegradable poly (butylene adipate-co-terephthalate) (PBAT) and microcrystalline cellulose (MCC) to improve mechanical properties has always been a considerable challenge. Herein, a series of copolyesters (MCP) to solve the above problem are prepared from terephthalic acid, adipic acid, 1, 4-butanediol, MCC, glycerol, and citric acid via atmospheric pressure esterification–polycondensation–reduced pressure esterification. The crystallinity of MCP-1 (1 wt% MCC) compared with pure PBAT (P-0) was enhanced by 7.8%. The melting point and the initial decomposition temperature of MCP-1 were 133 ℃ and 402 ℃, respectively. These results demonstrated superior thermal stability of MCP-1. Based on rheological measurements, dynamic mechanical analysis and scanning electron microscope results, within the added amount of 1 wt% MCC, better compatibility, interfacial interaction enhancement, and micro-phase separation nearly disappeared from PBAT and MCC in MCP was displayed. Additionally, the puncture load and tearing strength of the MCP-1 were attained 25.69 N and 197.61 N/mm, which was increased by approximately 113.7% and 66.4% compared to P-0. Surprisingly, the enzymatic degradation of blend PBAT/MCC (P) seemed to be little affected by MCC, whereas the degradation performance of MCP, relative to the P-0 was improved. These results indicate that MCP-1 possessed better compatibility, crystallinity, puncture load, tearing strength, and interfacial interaction. Overall, a new strategy to solve the problem for interface between PBAT and MCC is provided and promotes the application of PBAT in degradable film, foam, and elastomer.