Flexible transparent electrodes are in significant demand in applications including solar cells, light-emitting diodes, and touch panels. The combination of high optical transparency and high electrical conductivity, however, sets a stringent requirement on electrodes based on metallic materials. To obtain practical sheet resistances, the visible transmittance of the electrodes in previous studies is typically lower than the transparent substrates the electrode structures are built on, namely, the transmittance relative to the substrate is <100%. Here, we demonstrate a flexible dielectric-metal-dielectric-based electrode with ~88.4% absolute transmittance, even higher than the ~88.1% transmittance of the polymer substrate, which results in a relative transmittance of ~100.3%. This non-trivial performance is achieved by leveraging an optimized dielectric-metal-dielectric structure guided by analytical and quantitative principles described in this work, and is attributed to an ultra-thin and ultra-smooth copper-doped silver film with low optical loss and low sheet resistance.
Based
on classical nucleation theory, the current entropic reduction model
(ERM) of flow-induced crystallization (FIC) treats external work as
perturbation on the framework of equilibrium thermodynamics, which,
however, obscures the nonequilibrium nature of FIC. In this work, in situ investigation on FIC under strong flow by combining
a unique homemade extensional rheometer and ultrafast X-ray scattering
reveals a constant critical strain or time for nucleation in isotactic
polypropylene melt in a wide temperature range from 130 to 170 °C.
Our discovery contradicts the strain–temperature equivalence
predicted by ERM but unveils the nonequilibrium nature of FIC. To
account for the temperature independence of flow-induced nucleation,
a tentative kinetic pathway of nucleation describing stretch-induced
hierarchical structural transitions is proposed through which the
capability of flow as driving force is justified.
The demand for high‐performance absorbers in the microwave frequencies, which can reduce undesirable radiation that interferes with electronic system operation, has attracted increasing interest in recent years. However, most devices implemented so far are opaque, limiting their use in optical applications that require high visible transparency. Here, a scheme is demonstrated for microwave absorbers featuring high transparency in the visible range, near‐unity absorption (≈99.5% absorption at 13.75 GHz with 3.6 GHz effective bandwidth) in the Ku‐band, and hence excellent electromagnetic interference shielding performance (≈26 dB). The device is based on an asymmetric Fabry–Pérot cavity, which incorporates a monolayer graphene and a transparent ultrathin (8 nm) doped silver layer as absorber and reflector, and fused silica as the middle dielectric layer. Guided by derived formulism, this asymmetric cavity is demonstrated with microwaves near‐perfectly and exclusively absorbs in the ultrathin graphene film. The peak absorption frequency of the cavity can be readily tuned by simply changing the thickness of the dielectric spacer. The approach provides a viable solution for a new type of microwave absorber with high visible transmittance, paving the way towards applications in the area of optics.
Natural enzymes are highly specific biocatalysts that can selectively catalyse specific biological reactions. However, their high preparation cost and easy deactivation of natural enzymes limit their practical applications. In the...
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