35 research outputs found
Wetting of Inkjet Polymer Droplets on Porous Alumina Substrates
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
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
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
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
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
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
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
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
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
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 polyÂethyleneÂimine (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