Ag2Se

Flexible thermoelectric generators (FTEGs), which can overcome the energy supply limitations of wearable devices, have received considerable attention. However, the use of toxic Te-based materials and fracture-prone electrodes constrains the application of FTEGs. In this study, a novel Ag2 Se and Poly (3,4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT:PSS)/multi-walled carbon nanotube (MWCNT) FTEG with a high output performance and good flexibility is developed. The thermoelectric columns formulated in the work are environmentally friendly and reliable...

Skin is critical for shaping our interactions with the environment. The electronic skin (E-skin) has emerged as a promising interface for medical devices to replicate the functions of damaged skin. However, exploration of thermal perception, which is crucial for physiological sensing, has been limited. In this work, a multifunctional E-skin based on flexible thermoelectric Ag2 Se films is proposed, which utilizes the Seebeck effect to replicate the sensory functions of natural skin. The E-skin can enable capabilities including temperature perception, tactile perception, contactless perception, and material recognition by analyzing the thermal conduction behaviors of various materials...

Fluorescent lateral flow immunoassay (LFA), one tool in point of care testing (POCT) systems for breast cancer, has attracted attention because it is quick, simple, and convenient. However, samples and the constituent material exhibit autofluorescence in the visible region, which is a very large obstacle in the development of fluorescent LFAs. The autofluorescence of biological samples is scarcely found in the second near-infrared (NIR-II) range and samples scatter and absorb less NIR-II light than visible light...

Nanoparticles have drawn significant interest in a range of applications, ranging from biomedical to environmental sciences, due to their distinctive physicochemical characteristics. In this study, it was reported that simple biological production of Ag, Se, and bimetallic Ag2 Se nanoparticles (NPs) with Pseudomonas aeruginosa is a promising, low-cost, and environmentally friendly method. For the first time in the scientific literature, Ag2Se nanoparticles have been generated via green bacterial biosynthesis...

Herein, an n-type Ag2 Se thermoelectric flexible thin film has been fabricated on a polyimide (PI) substrate via a novel thermal diffusion method, and the thermoelectric performance is well-optimized by adjusting the pressure and temperature of thermal diffusion. All of the Ag2 Se films are beneficial to grow (013) preferred orientations, which is conducive to performing a high Seebeck coefficient. By increasing the thermal diffusion temperature, the electrical conductivity can be rationally regulated while maintaining the independence of the Seebeck coefficient, which is mainly attributed to the increased electric mobility...

Flexible Ag2 Se thermoelectric (TE) films are promising for wearable applications near room temperature (RT). Herein, a Ag2 Se film on a nylon membrane with high TE performance was fabricated by a facile method. First, Ag2 Se powders were prepared by a microwave-assisted synthesis method using Ag nanowires as a template. Second, the Ag2 Se powders were deposited onto nylon via vacuum filtration followed by hot pressing. Through modulating the Ag/Se molar ratio for synthesizing the Ag2 Se powders, an optimized Ag2 Se film demonstrates a high power factor of 1577...

Herein, a flexible Ag2 Se/Se composite film with a high power factor has been fabricated on a nylon membrane. The film has a high density and contains well-crystallized Ag2 Se grains and embedded Se nanoinclusions, which exhibits not only excellent flexibility but also a comparably large room-temperature power factor and Seebeck coefficient of up to 2023 μW m-1 K-2 and -155 μV K-1 , respectively. The high Seebeck coefficient is ascribed to the energy-filtering effect as caused by the Se/Ag2 Se heterointerface...

Thermoelectric inorganic films are flexible when sufficiently thin. By removing the substrate, that is, making them free-standing, the flexibility of thermoelectric films can be enhanced to the utmost extent. However, studies on the flexibility of free-standing thermoelectric inorganic films have not yet been reported. Herein, the high thermoelectric performance and flexibility of free-standing thermoelectric Ag2 Se films are reported. Free-standing Ag2 Se films with a thickness of 25.0 ± 3.9 μm exhibited an in-plane zT of 0...

A flexible thermoelectric device has been considered as a competitive candidate for powering wearable electronics. Here, we fabricated an n-type Ag2 Se/Ag composite film on a flexible nylon substrate using vacuum-assisted filtration and a combination of cold and hot pressing. By optimising the Ag/Se ratio and the sequential addition and reaction time of AA, an excellent power factor of 2277.3 μW∙m-1 K-2 (corresponding to a ZT of ~0.71) at room temperature was achieved. In addition, the Ag2 Se/Ag composite film exhibits remarkable flexibility, with only 4% loss and 10% loss in electrical conductivity after being bent around a rod of 4 mm radius for 1000 cycles and 2000 cycles, respectively...

Low photoluminescence quantum difference rate and weak targeting ability make the practical application of NIR-II nanoparticles challenging. Here, NIR-II chiral rare-earth doped Ag 2 Se nanoparticles (defined as R- or S-Ag 2 Se NPs) were fabricated, exhibiting circular dichroism signal peak at 850 nm and fluorescence emission peak at 1550 nm, with 145.7-fold enhanced intensity compared to the reported Ag 2 Se NPs. Compared with S-Ag 2 Se NPs, a significant improvement in imaging efficiency of R-Ag 2 Se NPs was observed in living cells, which was attributed to a higher cellular uptake rate and 927...

Ag-Se nanostructure films were deposited on a-Se/nylon templates by a template-engaged reaction. Firstly, amorphous selenium (a-Se) was deposited on nylon by employing the chemical bath deposition method while using H2 SeO3 and Na2 SO3 solutions with an increasing selenium deposition time. Then, these a-Se/nylon templates were exposed into AgNO3 solution at ambient temperature and pressure. The Ag-Se/nylon nanocomposites surface morphology, elemental and phase composition, and optical properties were monitored depending on the selenium deposition time on nylon...

In this work, (Ag, In)-co-doped Cu2 SnSe3 -based compounds are prepared using a self-propagating high-temperature synthesis process. Ag2 Se and as-synthesized (Ag, In)-co-doped Cu2 SnSe3 -based powders are mixed in a proportion according to the formula of Cu1.85 Ag0.15 Sn0.91 In0.09 Se3 / x Ag2 Se ( x = 0, 3, 4, and 5%), which is followed by a subsequent plasma-activated sintering (PAS) to obtain consolidated composite bulks. A sandwich experiment is designed to reveal the evolution of the microstructure and phase composition of the composite samples during the PAS process...

In this work, we developed a facile method to fabricate low-cost, flexible, and high-thermoelectric-performance n-type Ag2 Se1- x S x @(Ag2 S1- y Se y /S) composite film on a nylon membrane. The composite film was prepared by first performing wet-chemical synthesis of the S-doped Ag2 Se powder, then vacuum-assisted filtration of the powder on a nylon membrane, and finally hot-pressing. Transmission electron microscopy (TEM) observation and energy-dispersive system (EDS) analysis of the film revealed that the film had a porous network-like microstructure, in which Ag2 Se1- x S x sub-micron grains formed the skeleton and are coated by a ∼15 nm thick layer of S-rich Ag2 S1- y Se y nanograins mixed with an S amorphous phase...

Ag2 Se is a narrow band gap n-type semiconductor with high carrier mobility and low lattice thermal conductivity. It has high thermoelectric performance near room temperature. However, there is a noticeable data discrepancy for thermoelectric performance in the reported literature studies, which greatly hinders the rational understanding and potential application of this material. In this work, we comprehensively studied the homogeneity, reproducibility, and thermal stability of bulk Ag2 Se prepared by melting and mechanical alloying methods followed by spark plasma sintering...

Aiming to overcome both the structural and commercial limitations of flexible thermoelectric power generators (F-TEGs), we designed an efficient room-temperature aqueous selenization reaction that could be completed in air within less than 1 min, to directly fabricate thin β-Ag2 Se films consisting of perfectly crystalline and large columnar grains with both in-plane randomness and out-of-plane [201] preferred orientation. A high power factor (PF) of 2590 ± 414 μW m-1 K-2 and a figure-of-merit (zT) of 1...

In recent years, the preparation of flexible thermoelectric generators by screen printing has attracted wide attention due to easy processing and high-volume production. In this work, we propose an n-type Ag2 Se/polymer polyvinylpyrrolidone (PVP) film based on screen printing and investigate the effect of PVP on thermoelectric performance by varying the ratio of PVP. When the content ratio of Ag2 Se to PVP is 30:1, i.e., PI30, the fabricated PI30 film has the best thermoelectric property. The maximum power factor (PF) of the PI30 is 4...

Developing n-type materials with high peak and/or average ZT (ZT is the figure of merit) is an urgent need for the lower ZT of the existing n-type BiTeSe materials compared with the p-type BiSbTe materials. Here, we demonstrate that liquid-phase sintering can lead to lowered thermal conductivity and an improved power factor in n-type Ag2 Se, which originates from the greatly lowered electronic thermal conductivity attributed to the decreased mobility and improved Seebeck coefficients because of increased effective mass...

Structural polymorphism is known for many bulk materials; however, on the nanoscale metastable polymorphs tend to form more readily than in the bulk, and with more structural variety. One such metastable polymorph observed for colloidal Ag2 Se nanocrystals has traditionally been referred to as the "tetragonal" phase. While there are reports on the chemistry and properties of this metastable polymorph, its crystal structure, and therefore electronic structure, has yet to be determined. We report that an anti-PbCl2 -like structure type (space group P 21 / n ) more accurately describes the powder X-ray diffraction and X-ray total scattering patterns of colloidal Ag2 Se nanocrystals prepared by several different methods...

Silver selenide (Ag2Se) is a promising material for applications as a solid-state electrolyte, with a superionic phase transition at 133 °C. Here, we studied the temperature dependent transport properties of single Ag2Se nanowires in a transistor geometry, which allowed us to determine charge carrier type, concentration, and mobility below and above the superionic phase transition temperature. We found the majority charge carriers to be n-type in the temperature range of 30-150 °C. Across the superionic phase-transition, we observed a sudden increase in conductivity by about 30%, which was accompanied by an increase in charge carrier density by about 200% and a decrease in mobility by about 45%...

Although the Turing structures, or stationary reaction-diffusion patterns, have received increasing attention in biology and chemistry, making such unusual patterns on inorganic solids is fundamentally challenging. We report a simple cation exchange approach to produce Turing-type Ag 2 Se on CoSe 2 nanobelts relied on diffusion-driven instability. The resultant Turing-type Ag 2 Se-CoSe 2 material is highly effective to catalyze the oxygen evolution reaction (OER) in alkaline electrolytes with an 84.5% anodic energy efficiency...