Flexible thermoelectric generators offer the possibility of harvesting waste heat from the human body. However, intrinsic brittleness and the high production cost of bulk thermoelectric materials ...limit their applications in flexible thermoelectric generators. Herein, flexible Ag2Se/carbon nanocomposite films on polyimide substrates are prepared by scalable screen-printing followed by facial heat treatment. An optimal film shows a maximum power factor of 1617 μW m−1 K−2 at room temperature and good flexibility. The film consists of mainly Ag2Se grains with a preferred (00Ɩ)-orientation and a small amount of carbon. Microstructure observations reveal that the Ag2Se grains with sizes of nano to micrometers have coherent or continuous grain boundaries, and the carbon is mainly amorphous with slight graphitization. A flexible thermoelectric device assembled with the optimal film exhibits a power density of 29.1 W/m2 at a temperature gradient of 35.4 K. This work demonstrates a cost-effective route to high-performance flexible thermoelectric films.
A flexible Ag2Se/carbon nanocomposite film on a polyimide substrate prepared by scalable screen-printing exhibits a high power factor of 1617 μW m−1 K−2 at room temperature and a flexible thermoelectric device assembled presents a maximum power density of 29.1 W/m2 at a temperature difference of 35.4 K. Display omitted
•Ag2Se/carbon nanocomposite films were prepared by scalable screen-printing.•An optimal film exhibits a power factor of 1617 μW m−1 K−2 at room temperature.•The film possesses good flexibility.•A flexible thermoelectric device assembled shows high output properties.
Antennas operating at high frequency bands are sought after for applications in 5G, satellite, radar, and other communication systems. Graphene, a two-dimensional material known for its exceptional ...conductivity, mechanical strength, and chemical stability, is anticipated to serve as a viable substitute for copper in antenna applications. However, researches on graphene antennas at millimeter-wave and higher frequencies are mainly limited to theory and simulation, due to the fabrication challenges of achieving high-precision graphene patterns. Herein, we present the design and fabrication of a graphene folded reflectarray antenna (FRA) operating at millimeter-wave. The FRA is fabricated using screen-printing of graphene ink on an RT5880 substrate, followed by laser engraving for precise patterning. The main reflector has 918 patch units, and the polarizing grids have line widths and spacings of 100 μm. Measurements demonstrate that the antenna has a realized peak gain of 21.37 dBi at 37.5 GHz. The radiation patterns show a 3 dB beamwidth of 6° and 4° in the E-plane and H-plane respectively, with cross-polarization more than −18 dB. The laser-assisted screen-printing method provides a feasible strategy for the precision manufacture of graphene communication devices.
Display omitted
Abstract
The fabrication of fully printable, flexible micro‐supercapacitors (MSCs) with high energy and power density remains a significant technological hurdle. To overcome this grand challenge, the ...2D material MXene has garnered significant attention for its application, among others, as a printable electrode material for high performing electrochemical energy storage devices. Herein, a facile and in situ process is proposed to homogeneously anchor hydrous ruthenium oxide (RuO
2
) nanoparticles on Ti
3
C
2
T
x
MXene nanosheets. The resulting RuO
2
@MXene nanosheets can associate with silver nanowires (AgNWs) to serve as a printable electrode with micrometer‐scale resolution for high performing, fully printed MSCs. In this printed nanocomposite electrode, the RuO
2
nanoparticles contribute high pseudocapacitance while preventing the MXene nanosheets from restacking, ensuring an effective ion highway for electrolyte ions. The AgNWs coordinate with the RuO
2
@MXene to guarantee the rheological property of the electrode ink, and provide a highly conductive network architecture for rapid charge transport. As a result, MSCs printed from the nanocomposite inks demonstrate volumetric capacitances of 864.2 F cm
−3
at 1 mV s
−1
, long‐term cycling performance (90% retention after 10 000 cycles), good rate capability (304.0 F cm
−3
at 2000 mV s
−1
), outstanding flexibility, remarkable energy (13.5 mWh cm
−3
) and power density (48.5 W cm
−3
).
Building-integrated photovoltaic (BIPV) is crucial for emission reduction and energy transition in urban areas. However, the limited aesthetic appearance hinders the popularization of BIPV as ...traditional photovoltaic (PV) modules are usually black and dark blue, therefore, colorization of PV modules can solve the problem and pave the way for the further development of BIPV. In this study, some high-efficiency colored crystalline silicon (c-Si) PV modules prepared by screen printing the front glass with pearlescent pigments are developed. A suitable pigment for the colorization of PV modules, namely the synthetic mica-based interference pearlescent pigment, was finalized by analyzing the interference theories and comparing present and potential pigments. An adjusted coloring layer thickness from 15.50 μm to 57.17 μm was then realized, which contributed to a variable lightness (L*) from 39.3 to 46.9. Besides, a series of PV modules with various colors used for building facades that could retain 93.71 % of original power generation ability, were produced for different design choices. Moreover, 15 cm × 15 cm bicolor patterned PV modules with a precise motif were fabricated, which can achieve a satisfying power conversion efficiency (PCE) of 18.64 %, only a 5.44 % relative reduction of power generation ability compared with the reference PV module (PCE = 19.71 %). The colorization method for single-colored and patterned PV modules not only guarantees power generation ability but also provides an aesthetic appearance for BIPV applications.
•A suitable pigment was finalized for the colorization of photovoltaic (PV) modules.•The aesthetics can be easily regulated by adjusting plate structures and pigments.•There is a linear relationship between the PCE loss and the amount of pigments.•The PCE of colored PV modules achieved at least 20.18 %, a relative loss of 11.30 %.•Color-patterned PV modules realized a relative efficiency loss of only 5.44 %.
Display omitted
The industrial scale production and application of liquid conductive nanomaterials with well-defined conductive properties, printing adaptability and mechanical properties are crucial ...for the flexible electronic devices. Although graphene can be used as an attractive liquid nanoink platform for electronic devices, it is still a major challenge to prepare graphene conductive inks with high concentration, conductivity and stability with graphene powders as raw materials and improve the post-treatment process for printed patterns. Here, a novel graphene-based screen printing conductive ink employing liquid-exfoliated graphene powders produced by jet cavitation and carbon black jointly as conductive filler is presented. The inks with graphene powders containing thicker smaller-area flakes and carbon black fraction of 15% in the total conductive fillers exhibit printability down to lines of 90 μm in width and printed pattern electrical conductivity of 2.15 × 104 S/m at 7 μm thickness along with outstanding mechanical properties. Also, special post-treatment, i.e. heating-compression rolling-heating, makes the conductive ink formulation compatible with a wide range of substrates and suitable for Roll-to-Roll applications. Overall, this paper provides a new solution to high-efficiency, low-cost, large-scale production of printed flexible electronics.
A novel capacitive pressure sensor based on micro-structured polydimethylsiloxane (PDMS) dielectric layer was developed for wearable E-skin and touch sensing applications. The pressure sensor was ...fabricated on a flexible polyethylene terephthalate (PET) substrate, using PDMS and silver (Ag) as the dielectric and electrode layers, respectively. A set of PDMS films with pyramid shaped micro-structures were fabricated using a laser engraved acrylic mold. The electrodes (top and bottom) were fabricated by depositing Ag on PET films using additive screen-printing process. The pressure sensor was assembled by attaching the top and bottom Ag electrodes to the smooth side of pyramid shaped micro-structured PDMS (PM-PDMS) films. The top PM-PDMS was then placed on the bottom PM-PDMS. The capability of the fabricated pressure sensor was investigated by subjecting the sensor to pressures ranging from 0 to 10 kPa. A sensitivity of 0.221% Pa<inline-formula> <tex-math notation="LaTeX">^{\mathbf {-1}} </tex-math></inline-formula>, 0.033% Pa<inline-formula> <tex-math notation="LaTeX">^{\mathbf {-1}} </tex-math></inline-formula> and 0.011% Pa<inline-formula> <tex-math notation="LaTeX">^{\mathbf {-1}} </tex-math></inline-formula> along with a correlation coefficient of 0.9536, 0.9586 and 0.9826 was obtained for the pressure sensor in the pressure range of 0 Pa to 100 Pa, 100 Pa to 1000 Pa, and 1 kPa to 10 kPa, respectively. The pressure sensor also possesses a fast response time of 50 ms, low hysteresis of 0.7%, recovery time of 150 ms and excellent cycling stability over 1000 cycles. The results demonstrated the efficient detection of pressure generated from various activities such as hand gesture and carotid pulse measurement. The PM-PDMS based pressure sensor offers a simple and cost-effective approach to monitor pressure in E-skin applications.
In this study, we report a facile chemical synthesis of a novel MnCo2S4/halloysite (HNTs) nanoflakes decorated on nanotubes which coated on Ni foam via a screen-printing technique. The MnCo2S4 thin ...films were prepared using a coprecipitation method which demonstrate battery kind of behavior. The MnCo2S4/HNTs-based electrode shows a specific capacity of 359 mAh g−1 at 5 mV s−1 with excellent cycling stability. Furthermore, the symmetric system exhibits an outstanding energy density and power density of 6.98 Wh kg−1 and 1976.0 W kg−1, respectively. The results obtained with the MnCo2S4/HNTs composite in a symmetric system indicate that this composite material can potentially be used as an alternative electrode material for electrochemical energy storage.
Display omitted
•Innovative halloysite nanotubes (HNTs) like nanostructures covered on MnCo2S4 nanoflakes.•MnCo2S4/HNTs prepared hybrid composite using a simple screen-printing technique.•The MnCo2S4/HNTs offering excellent specific capacities and cycling stability.•Hybrid MnCo2S4/HNTs electrode provided higher surface area for supercapacitor.
Expanding the practical application range of self‐healing materials has become an important challenge for developing smart materials. Herein, the synthesis of printable, triple‐mode fluorescence ...responsive, and colorless self‐healing elastomers, formed by the combination of disulfide cross‐linked polyurethane (PU) polymers, carbon dots (CDs) down‐conversion fluorescence materials, and lanthanide ions doped upconversion fluorescence materials. The PU elastomers with optimal mechanical properties and good restorability (recover large strain of 500% after relaxation at room temperature (R.T.) for 2 h) are selected to incorporate CDs for fabricating fluorescence responsive elastomers (denoted as PU‐CDs). Significantly, the prepared PU‐CDs exhibit not only superior tensile strength and toughness (20.95 MPa and 85.13MJ m–3, respectively) than the previously reported R.T. self‐healing elastomers but also show good self‐healing properties and achieve blue fluorescence emissions under the ultraviolet excitation. Furthermore, a series of dual‐mode fluorescence patterns based on formulated core@shell structural upconversion inks are prepared on the transparent PU‐CDs elastomers by a directly screen‐printing method. Self‐healing and integrating a series of fluorescence patterns and damaged electrical patterns can also be accomplished successfully. The designed self‐healing materials provide new ideas and important guidance for developing and applying the next generation of smart materials.
This study designs a novel printable triple‐mode down/up‐conversion fluorescence responsive, colorless, and transparent room temperature self‐healing elastomer. The elastomer can exhibit blue emissions under UV excitation and dual‐mode designable fluorescence patterns under 980 and 808 nm irradiation. This study can provide new and important guidance for the development and application of the next generation of self‐healing materials.
Li-ion batteries are life-saving energy storage technology. However, the battery manufacturing process still needs complicated and expensive production lines because of the sensitive nature of active ...materials towards the open atmosphere. Additionally, employing hazardous N-Metil-2-Pirrolidon (NMP) solvents, which are also restricted by the World Health Organization for electrode preparation, contributes to unsafe working conditions. In this study, water-based LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode inks were produced and printed by the screen-printing method, which is widely used in sensors and electronics fabrication due to its potential practical applications and low-cost production possibilities. Despite their suitability for operation at high voltage ranges, NMC811 cathodes typically exhibit rapid capacity drops over time because of side reactions and Cathode-Electrolyte Interphase (CEI) thickening. In this study, to overcome the capacity drop issue and make it possible to produce water-based cathode inks, NMC811 particles were encapsulated with reduced graphene oxide (rGO) via a hydrothermal method. Water-based Carboxymethyl cellulose (CMC) - Polyethylene oxide (PEO) binders are compared with conventional Polyvinylidene fluoride (PVDF)-NMP binders and exhibited promising electrochemical stability of 75 % after 50 cycles within a high voltage range of 2.8–4.6 V. Therefore, the water-based novel cathode ink presented in this study is not only well-suited for advancing the development of printed batteries but also stride towards more eco-friendly processes thanks to replacing the toxic NMP with water. Moreover, battery printing technologies have also a strategic importance by reducing the investment cost of battery-producing.
The incorporation of lead-free BaTiO3 particles into P(VDF-TrFE) provides a versatile way for tuning dielectric and piezoelectric properties. Screen-printing enables the easy production of flexible ...capacitors. To prevent particle aggregation, the BaTiO3 particles are functionalized with a surfactant. Initially, 60 % vol. BaTiO3 particles are deposited in the second layer out of three layers. After annealing and cooling, the particle distribution is successfully homogeneous in the whole film. After poling at 80 °C, the relative permittivity and the piezoelectric coefficient d33 significantly increase up to 159 and 8 pC/N respectively. In situ/operando spatially-resolved X-ray techniques allow exploring the structural evolution of the composite device during annealing and during an applied electric field. The application of an electric field leads to the quasi-disappearance of the P(VDF-TrFE) ferroelectric state. As a matter of fact, the interactions between the P(VDF-TrFE) and the surfactant may limit the rotation of P(VDF-TrFE) chains near the particles. Hence, paraelectric polymers could be chosen on a mechanical or economic basis for the matrix in piezoelectric composite devices. Regarding BaTiO3, the lattice strain evolves from an extrinsic strain at RT to an intrinsic strain after annealing and cooling. At the cooled state, the tetragonality c/a is higher than 1.01, leading to improved piezoelectric properties. The increase of the average domain size leads to the increase of the composite permittivity. Finally this knowledge facilitates the development of tailored flexible piezoelectric composite devices.
Display omitted
•BaTiO3 particles are homogeneously distributed in screen-printed flexible capacitors.•The P(VDF-TrFE) ferroelectric state disappears during electric field application.•Permittivity of the composite is increased due to larger particle domains.•Piezoelectric properties are improved by larger tetragonality of BaTiO3.
