35 research outputs found

    Wetting of Inkjet Polymer Droplets on Porous Alumina Substrates

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    The resolution of inkjet printing technology is determined by wetting and evaporation processes after the jet drop contacts the substrate. Here, the wetting of different picoliter solubilized polymer droplets jetting onto one-end-closed porous alumina was investigated. The selected polymers are commonly used in inkjet ink. The synergistic effects of the hierarchical structure and substrate surface modification were used to control the behavior of polymer-based ink drops. A model that invokes the effect of surface tension was applied to calculate the amount of polymer solution penetrating into the pores. The calculation corroborates experimental observations and shows that the volume of polymer solution in the pores increases with an increase in pore radius and depth, resulting in less solution remaining on the substrate surface. The structure of the porous substrate coupled with intrinsic polymer properties and surface modifications all contribute to the resolution that can be achieved via inkjet printing

    Spontaneous Uphill Movement and Self-Removal of Condensates on Hierarchical Tower-like Arrays

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    Fast removal of condensates from surfaces is of great significance due to the enhanced thermal transfer coefficient and continuous condensation. However, the lost superhydrophobicity of lotus leaves intrigues us to determine what kind of surface morphologies meets the self-removal of condensates? The uphill movement of condensates in textured surfaces is vital to avoid flooding and facilitating self-removal. Here, superhydrophobic microtower arrays were designed to explore the spontaneous uphill movement and Wenzel to Cassie transition as well as the self-removal of condensates. The tower-like arrays enable spontaneous uphill movement of tiny condensates entrapped in microstructures due to the large upward Laplace pressure, which is ∼30 times larger than that on cone-like arrays. The sharp tips decrease the adhesion to suspending droplets and promote their fast self-removal. These results are important for designing desirable textured surfaces by enlarging upward Laplace pressure to facilitate condensate self-removal, which is widely applied in self-cleaning, antifogging, anti-icing, water harvesting, and thermal management systems

    Designing Laplace Pressure Pattern for Microdroplet Manipulation

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    Manipulation of arrayed tiny droplets is important in liquid dispersion, liquid transportation, bioassays, nucleation, integrated electronics, and various lab experiments that require delivering precise and minute volumes of droplets. Liquid dispensed from a small orifice or split from surface patterns are typical methods, but the acquired droplet diameters are similar to that of the nozzle and pattern. Here we demonstrate that tiny droplets with dimensions much smaller than the pattern can be arrayed advantageously through designing a Laplace pressure pattern based on conical morphology and wetting heterogeneity. The pattern could selectively resist liquid’s motion and drive the capillary bridge breaking of macrodrop into arrayed tiny droplets at wettability boundaries. Arrayed picoliter droplets can be acquired on a submillimeter-scaled pattern with a feature size of several hundred micrometers. Through regulating the conical morphologies and the wetting heterogeneity, the volume and number of tiny droplets can be accurately controlled. As a paradigm, adopting droplets of nanoparticle dispersion, various arrayed functional assemblies can be fabricated. This integration of conical morphology and wetting heterogeneity offers a powerful kit for patterned microdroplets quantitative and locational manipulation and opens a new avenue to achieve functional units in a facile and high-throughput way

    Tautomeric Passivation Strategy-Assisted Photostable Perovskite Solar Modules

    No full text
    Defects weaken the stability of perovskite solar modules (PSMs) and aggravate the photodegradation process under continuous illumination (especially, UV light), limiting the competitiveness and commercial development of perovskite photovoltaics. Herein, we propose a tautomeric passivation strategy toward molecular isomerism passivation, 2,3-Bis(2,4,5-trimethyl-3-thienyl) maleimide (DAE), to assist defect passivation for photostable PSMs with sustainable UV protection. The tautomeric DAE molecule in the perovskite film after UV irradiation presents high charge density difference values (−0.182e for −CO–Pb; 0.015e for N–H···I–) and efficiently improves the defect formation energy, preventing perovskite UV degradation through the free closed and open rings of the DAE molecule in the PSM. The DAE PSCs exhibit champion efficiencies up to 24.12% (small area: 0.08 cm2) and 18.47% (module area: 25 cm2) as well as long-term UV photostability, continuously charging a mobile phone through a DAE-PSM even on a cloudy day

    Tautomeric Passivation Strategy-Assisted Photostable Perovskite Solar Modules

    No full text
    Defects weaken the stability of perovskite solar modules (PSMs) and aggravate the photodegradation process under continuous illumination (especially, UV light), limiting the competitiveness and commercial development of perovskite photovoltaics. Herein, we propose a tautomeric passivation strategy toward molecular isomerism passivation, 2,3-Bis(2,4,5-trimethyl-3-thienyl) maleimide (DAE), to assist defect passivation for photostable PSMs with sustainable UV protection. The tautomeric DAE molecule in the perovskite film after UV irradiation presents high charge density difference values (−0.182e for −CO–Pb; 0.015e for N–H···I–) and efficiently improves the defect formation energy, preventing perovskite UV degradation through the free closed and open rings of the DAE molecule in the PSM. The DAE PSCs exhibit champion efficiencies up to 24.12% (small area: 0.08 cm2) and 18.47% (module area: 25 cm2) as well as long-term UV photostability, continuously charging a mobile phone through a DAE-PSM even on a cloudy day

    Tautomeric Passivation Strategy-Assisted Photostable Perovskite Solar Modules

    No full text
    Defects weaken the stability of perovskite solar modules (PSMs) and aggravate the photodegradation process under continuous illumination (especially, UV light), limiting the competitiveness and commercial development of perovskite photovoltaics. Herein, we propose a tautomeric passivation strategy toward molecular isomerism passivation, 2,3-Bis(2,4,5-trimethyl-3-thienyl) maleimide (DAE), to assist defect passivation for photostable PSMs with sustainable UV protection. The tautomeric DAE molecule in the perovskite film after UV irradiation presents high charge density difference values (−0.182e for −CO–Pb; 0.015e for N–H···I–) and efficiently improves the defect formation energy, preventing perovskite UV degradation through the free closed and open rings of the DAE molecule in the PSM. The DAE PSCs exhibit champion efficiencies up to 24.12% (small area: 0.08 cm2) and 18.47% (module area: 25 cm2) as well as long-term UV photostability, continuously charging a mobile phone through a DAE-PSM even on a cloudy day

    Tautomeric Passivation Strategy-Assisted Photostable Perovskite Solar Modules

    No full text
    Defects weaken the stability of perovskite solar modules (PSMs) and aggravate the photodegradation process under continuous illumination (especially, UV light), limiting the competitiveness and commercial development of perovskite photovoltaics. Herein, we propose a tautomeric passivation strategy toward molecular isomerism passivation, 2,3-Bis(2,4,5-trimethyl-3-thienyl) maleimide (DAE), to assist defect passivation for photostable PSMs with sustainable UV protection. The tautomeric DAE molecule in the perovskite film after UV irradiation presents high charge density difference values (−0.182e for −CO–Pb; 0.015e for N–H···I–) and efficiently improves the defect formation energy, preventing perovskite UV degradation through the free closed and open rings of the DAE molecule in the PSM. The DAE PSCs exhibit champion efficiencies up to 24.12% (small area: 0.08 cm2) and 18.47% (module area: 25 cm2) as well as long-term UV photostability, continuously charging a mobile phone through a DAE-PSM even on a cloudy day

    Tautomeric Passivation Strategy-Assisted Photostable Perovskite Solar Modules

    No full text
    Defects weaken the stability of perovskite solar modules (PSMs) and aggravate the photodegradation process under continuous illumination (especially, UV light), limiting the competitiveness and commercial development of perovskite photovoltaics. Herein, we propose a tautomeric passivation strategy toward molecular isomerism passivation, 2,3-Bis(2,4,5-trimethyl-3-thienyl) maleimide (DAE), to assist defect passivation for photostable PSMs with sustainable UV protection. The tautomeric DAE molecule in the perovskite film after UV irradiation presents high charge density difference values (−0.182e for −CO–Pb; 0.015e for N–H···I–) and efficiently improves the defect formation energy, preventing perovskite UV degradation through the free closed and open rings of the DAE molecule in the PSM. The DAE PSCs exhibit champion efficiencies up to 24.12% (small area: 0.08 cm2) and 18.47% (module area: 25 cm2) as well as long-term UV photostability, continuously charging a mobile phone through a DAE-PSM even on a cloudy day

    Tautomeric Passivation Strategy-Assisted Photostable Perovskite Solar Modules

    No full text
    Defects weaken the stability of perovskite solar modules (PSMs) and aggravate the photodegradation process under continuous illumination (especially, UV light), limiting the competitiveness and commercial development of perovskite photovoltaics. Herein, we propose a tautomeric passivation strategy toward molecular isomerism passivation, 2,3-Bis(2,4,5-trimethyl-3-thienyl) maleimide (DAE), to assist defect passivation for photostable PSMs with sustainable UV protection. The tautomeric DAE molecule in the perovskite film after UV irradiation presents high charge density difference values (−0.182e for −CO–Pb; 0.015e for N–H···I–) and efficiently improves the defect formation energy, preventing perovskite UV degradation through the free closed and open rings of the DAE molecule in the PSM. The DAE PSCs exhibit champion efficiencies up to 24.12% (small area: 0.08 cm2) and 18.47% (module area: 25 cm2) as well as long-term UV photostability, continuously charging a mobile phone through a DAE-PSM even on a cloudy day

    Polyethyleneimine High-Energy Hydrophilic Surface Interfacial Treatment toward Efficient and Stable Perovskite Solar Cells

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    The interfacial contact is critical for the performance of perovskite solar cells (PSCs), leading to dense perovskite thin films and efficient charge transport. In this contribution, an effective interfacial treatment solution using poly­ethylene­imine (PEI) was developed to improve the performance and stability of PSCs. Inserting PEI between the s-VO<sub><i>x</i></sub> and perovskite layers can produce a high-energy hydrophilic surface to facilitate the formation of a high-quality perovskite layer by the solution method. Accordingly, the surface coverage of perovskite film on the s-VO<sub><i>x</i></sub> layer increased from 80% to 95%, and the PCE of the device improved from 12.06% (with an average of 10.16%) to 14.4% (with an average value of 12.8%) under an irradiance of 100 mW cm<sup>–2</sup> AM 1.5G sunlight. More importantly, the stability of PSCs was further improved after adding another PEI layer between the electron transport layer and LiF/Al layer, less than 10% decay in efficiency during a 10-days observation. Since all layers of the PSCs were fabricated at low temperature (<150 °C), these PEI-treated PSCs based on the amorphous VO<sub><i>x</i></sub> layer have the potential to contribute significantly toward the development of efficient and stable solar cells on flexible substrates
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