Conductive
coatings show great promise for next-generation electromagnetic
interference (EMI) shielding challenges on textile; however, their
stringent requirements for electrical conductivity are difficult to
meet by conventional approaches of increasing the loading and homogeneity
of conductive nanofillers. Here, the axial alignment of carbon nanotubes
(CNTs) on fibers that were obtained by spontaneous capillary-driven
self-assembly is shown on commercial cotton fabrics, and its great
potential for EMI shielding is demonstrated. The aligned CNTs structurally
optimize the conductive network on fabrics and yield an 81-fold increase
in electrical conductivity per unit of CNT, compared with the disordered
CNT microstructure. The high-efficiency electrical conductivity allows
a several-micron-thick coating on insulating fabrics to endow an EMI
shielding effectiveness of 21.5 dB in the X band and 20.8 dB in the
Ku band, which meets the standard shielding requirement in commercial
applications. It is among the minimum reported thicknesses for conductive
nanocomposite coatings to date. Moreover, the coated fabrics with
aligned CNTs possess a desirable stability upon bending, scratching,
stripping, and even washing, which is attributed to the dense CNT
packing in the aligned microarchitecture. This work presents the anisotropic
structure on large areas by self-assembly, offering new opportunities
for next-generation portable and wearable electronic devices.
Colloidal quantum wells (CQWs) have emerged as a promising family of two-dimensional (2D) optoelectronic materials with outstanding properties, including ultranarrow luminescence emission, nearly unity quantum yield, and large extinction coefficient. However, the performance of CQWs-based light-emitting diodes (CQW-LEDs) is far from satisfactory, particularly for deep red emissions (≥660 nm). Herein, high efficiency, ultra-low-efficiency roll-off, high luminance, and extremely saturated deep red CQW-LEDs are reported. A key feature for the high performance is the understanding of charge dynamics achieved by introducing an efficient electron transport layer, ZnMgO, which enables balanced charge injection, reduced nonradiative channels, and smooth films. The CQW-LEDs based on (CdSe/CdS)@(CdS/CdZnS) ((core/crown)@(colloidal atomic layer deposition shell/hot injection shell)) show an external quantum efficiency of 9.89%, which is a record value for 2D nanocrystal LEDs with deep red emissions. The device also exhibits an ultra-low-efficiency roll-off and a high luminance of 3853 cd m −2 . Additionally, an exceptional color purity with the CIE coordinates of (0.719, 0.278) is obtained, indicating that the color gamut covers 102% of the International Telecommunication Union Recommendation BT 2020 (Rec. 2020) standard in the CIE 1931 color space, which is the best for CQW-LEDs. Furthermore, an active-matrix CQW-LED pixel circuit is demonstrated. The findings imply that the understanding of charge dynamics not only enables high-performance CQW-LEDs and can be further applied to other kinds of nanocrystal LEDs but also is beneficial to the development of CQW-LEDs-based display technology and related integrated optoelectronics.
Controlling solar
transmission through windows promises to reduce building energy consumption.
A new smart window for adaptive solar modulation is presented in this
work proposing the combination of the photothermal one-dimensional
(1D) Au nanochains and thermochromic hydrogel. In this adaptive solar
modulation system, the Au nanochains act as photoresponsive nanoheaters
to stimulate the optical switching of the thermochromic hydrogel.
By carefully adjusting the electrostatic interactions between nanoparticles,
different chain morphologies and plateau-like broad-band absorption
in the NIR region are achieved. Such broad-band-absorbed 1D nanochains
possess excellent thermoplasmonic effect and enable the solar modulation
with compelling features of improved NIR light shielding, high initial
visible transmittance, and fast response speed. The designed smart
window based on 1D Au nanochains is capable of shielding 94.1% of
the solar irradiation from 300 to 2500 nm and permitting 71.2% of
visible light before the optical switching for indoor visual comfort.
In addition, outdoor cooling tests in model house under continuous
natural solar irradiation reveal the remarkable passive cooling performance
up to ∼7.8 °C for the smart window based on 1D Au nanochains,
showing its potential in the practical application of building energy
saving.
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