Manipulating the Macroscopic and Microscopic Morphology of Large-Area Gravure-Printed ZnO Films for High-Performance Flexible Organic Solar Cells

Gravure printing is a promising large-scale fabrication method for flexible organic solar cells(FOSCs)because it is compatible with two-dimension patternable roll-to-roll fabrication.However,the unsuitable rheological property of ZnO nanoinks resulted in unevenness and looseness of the gravure-printed ZnO interfacial layer.Here we propose a strategy to manipulate the macroscopic and microscopic of the gravure-printed ZnO films through using mixed solvent and poly(vinylpyrrolidone)(PVP)additive.The regulation of drying speed effectively manipulates the droplets fusion and leveling process and eliminates the printing ribbing structure in the macroscopic morphology.The additive of PVP effectively regulates the rheological property and improves the microscopic compactness of the films.Following this method,large-area ZnO∶PVP films(28×9 cm^(2))with excellent uniformity,compactness,conductivity,and bending durability were fabricated.The power conversion efficiencies of FOSCs with gravure-printed AgNWs and ZnO∶PVP films reached 14.34%and 17.07%for the 1 cm^(2)PM6:Y6 and PM6∶L8-BO flexible devices.The efficiency of 17.07%is the highest value to date for the 1 cm^(2)FOSCs.The use of mixed solvent and PVP addition also significantly enlarged the printing window of ZnO ink,ensuring high-quality printed thin films with thicknesses varying from 30 to 100 nm.

Freestanding and Flexible Interfacial Layer Enables Bottom-Up Zn Deposition Toward Dendrite-Free Aqueous Zn-Ion Batteries

Aqueous rechargeable zinc ion batteries are regarded as a competitive alternative to lithium-ion batteries because of their distinct advantages of high security,high energy density,low cost,and environmental friendliness.However,deep-seated problems including Zn dendrite and adverse side reactions severely impede the practical application.In this work,we proposed a freestanding Zn-electrolyte interfacial layer composed of multicapsular carbon fibers(MCFs)to regulate the plating/stripping behavior of Zn anodes.The versatile MCFs protective layer can uniformize the electric field and Zn^(2+)flux,meanwhile,reduce the deposition overpotentials,leading to high-quality and rapid Zn deposition kinetics.Furthermore,the bottom-up and uniform deposition of Zn on the Zn-MCFs interface endows long-term and high-capacity plating.Accordingly,the Zn@MCFs symmetric batteries can keep working up to 1500 h with 5 mAh cm^(−2).The feasibility of the MCFs interfacial layer is also convinced in Zn@MCFs||MnO_(2) batteries.Remarkably,the Zn@MCFs||α-MnO_(2)batteries deliver a high specific capacity of 236.1 mAh g^(−1)at 1 A g^(−1)with excellent stability,and maintain an exhilarating energy density of 154.3 Wh kg^(−1) at 33%depth of discharge in pouch batteries.

Flexible white top-emitting organic light-emitting diode with a MoO_x roughness improvement layer

In this paper, an MoOx film is deposited on a polyethylene terephthalate （PET） substrate as a buffer layer to improve the surface roughness of the flexible PET substrate. With an optimized MoOx thickness of 100 nm, the surface roughness of the PET substrate can be reduced to a very small value of 0.273 nm （much less than 0.585 nm of the pure PET）. Flexible white top-emitting organic light-emitting diodes （TEOLEDs） with red and blue dual phosphorescent emitting layers are constructed based on a low-reflectivity Sm/Ag semi-transparent cathode. The flexible white emission exhibits the best luminance and current injection characteristics with the 100-nm-thick MoOx buffer layer and this result indicates that a smooth substrate is beneficial to the enhancement of device electrical and electroluminescence performances. However, the white TEOLED with a 50-nm-thick MoOx buffer layer exhibits a maximum current efficiency of 4.64 cd/A and a power efficiency of 1.9 lm/W, slightly higher than those with a 100-nm MoOx buffer layer, which is mainly due to an obvious intensity enhancement but limited current increases in 50-nm MoOx-based white TEOLED. The change amplitudes of the Commission International de l’Eclairage （CIE） chromaticity coordinates are less than （0.016, 0.005） for all devices in a wide luminance range over 100 cd/m2, indicating an excellent color stability in our white flexible TEOLEDs. Additionally, the flexible white TEOLED with an MoOx buffer layer shows excellent flexibility to withstand more than 500 bending times under a curvature radius of approximately 9 mm. Research demonstrates that it is mainly attributed to the high surface energy of the MoOx buffer layer, which is conducible to the improvement of the surface adhesion to the PET substrate and the Ag anode.

Torsional effect of space structure in frequent earthquakes

Taking a concrete frame supporting space structure as the research object,we systematically studied its lateral-torsion coupling effect of reverse problems in consistent earthquake excitation.Firstly,based on its reverse forms and features,we put forward a mechanical analysis model(flexibility layer model) and a calculation method using the response spectrum method and the weighted average method,and verified their validity and feasibility using case analysis.The result shows that the translation displacement change trend of the space structure is basically the same whether reverse exists in the supporting structure or not,but the supporting structure torsion has an effect on the displacement with a relative increase of 10%.

Efficient fully laser-patterned flexible perovskite modules and solar cells based on low-temperature solution-processed SnO2/mesoporous-TiO2 electron transport layers

Efficient flexible perovskite solar cells and modules were developed using a combination of SnO2 and mesoporous-TiO2 as a fully solution-processed electron transport layer （ETL）. Cells using such ETLs delivered a maximum power conversion efficiency （PCE） of 14.8%, which was 30% higher than the PCE of cells with only SnO2 as the ETL. The presence of a mesoporous TiO2 scaffold layer over SnO2 led to higher rectification ratios, lower series resistances, and higher shunt resistances. The cells were also evaluated under 200 and 400 lx artificial indoor illumination and found to deliver maximum power densities of 9.77 μW/cm^2 （estimated PCE of 12.8%） and 19.2 μW/cm^2 （estimated PCE of 13.3%）, respectively, representing the highest values among flexible photovoltaic technologies reported so far. Furthermore, for the first time, a fully laser-patterned flexible perovskite module was fabricated using a complete three-step laser scribing procedure （P1, P2, P3） with a PCE of 8.8% over an active area of 12 cm^2 under an illumination of 1 sun.

Interfacial engineering of printable bottom back metal electrodes for full-solution processed flexible organic solar cells

Printing of metal bottom back electrodes of flexible organic solar cells（FOSCs） at low temperature is of great significance to realize the full-solution fabrication technology. However, this has been difficult to achieve because often the interfacial properties of those printed electrodes, including conductivity, roughness, work function,optical and mechanical flexibility, cannot meet the device requirement at the same time. In this work, we fabricate printed Ag and Cu bottom back cathodes by a low-temperature solution technique named polymer-assisted metal deposition（PAMD） on flexible PET substrates. Branched polyethylenimine（PEI） and ZnO thin films are used as the interface modification layers（IMLs） of these cathodes. Detailed experimental studies on the electrical, mechanical, and morphological properties, and simulation study on the optical properties of these IMLs are carried out to understand and optimize the interface of printed cathodes. We demonstrate that the highest power conversion efficiency over 3.0% can be achieved from a full-solution processed OFSC with the device structure being PAMDAg/PEI/P3 HT：PC61BM/PH1000. This device also acquires remarkable stability upon repeating bending tests.

Pencil painting like preparation for flexible thermoelectric material of high-performance p-type Na_(1.4)Co_(2)O_(4) and novel n-type NaxCo_(2)O_(4)

Flexible thermoelectric materials are presented with potential applications in electronic devices and energy conversion due to their convenient preparation,good flexibility,and various forms.However,as ductility is rarely observed in inorganic semiconductors and ceramic insulators,reports on applications of inorganic oxide materials in flexible thermoelectric materials are sparse.Here,we report a new method for the synthesis of a flexible Na_(1.4)Co_(2)O_(4) thermoelectric material based on Na_(1.4)Co_(2)O_(4) bulk materials,which are prepared by a self-flux method and painted on print paper.Seebeck coefficient and power factor of the obtained thermoelectric material are 78-102 μVK^(-1) and 159e223 mWm^-(1)K^(-2),respectively,in a temperature range of 303-522 K,which are superior to those values of other conductive polymers and their compounds.More interestingly,the n-type Na_(1.4)Co_(2)O_(4) flexible material is obtained in the painting process at higher pressure with Seebeck coefficients of109 to183 μVK^(-1) in a temperature range of 303-522 K.The convenient preparation method of these novel flexible thermoelectric materials may be expanded to the synthesis of other flexible thermoelectric materials,which will be the focus of future work.