Articles you may be interested inHighly-directional emission patterns based on near single guided mode extraction from GaN-based ultrathin microcavity light-emitting diodes with photonic crystals Appl. Phys. Lett. 97, 013108 (2010); 10.1063/1.3459970 Enhancement of light extraction from GaN-based green light-emitting diodes using selective area photonic crystal Appl. Phys. Lett. 96, 251103 (2010); 10.1063/1.3454240 Measurement of extraction and absorption parameters in GaN-based photonic-crystal light-emitting diodes

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Anisotropic light extraction of photonic crystal (PhC) light-emitting diodes in the azimuthal direction has been investigated with an annular structure of triangular PhC lattice. The optical images of the photoluminescence light extraction are obtained with laser excitation. For increasing lattice constant, sixfold symmetric patterns with varying numbers of petals in multiples of six are observed and analyzed. A map of the anisotropy for various lattice constants and numerical apertures is constructed. Several features of light propagations associated with the PhC are observed including the focusing and collimating behaviors.

We report a new design of the light‐emitting device which can be operated under alternating current source directly. The new type alternating current driven light‐emitting device (AC LED) can increase the radition area in each bias direction to improve the device efficiency by the Wheatstone Bridge (WB) circuit design. WB‐AC LEDs with different designs were fabricated and the electrical and optical characteristics were measured. It is found that the efficiency of the WB‐AC LED is influenced by the varied area ratio of the rectified microchip to the central one because of the different current density and forward bias of each microchip. Additionally, the relationship between the area ratio of microchips and the wall plug efficiency of the WB‐AC LED has also been discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A simple method is demonstrated to improve the folding reliability and sheet resistance of silver nanowire (Ag NW)-based transparent conductive films (TCFs) without overcoated layers or complicated processes. As-coated Ag NW film is immersed in a silver-surrounded solution, in which the silver was reduced by Tollen's reagent. Therefore, the reduced silver can be deposited on the surface and crossing of Ag NWs to form a weld-like junction and bind the Ag NWs together, hence decreasing the contact resistance of Ag NW structure at wire-to-wire junctions by increasing the contact surface area. Compared with original Ag NW TCFs, this Ag NW junction structure not only shows compatibility with conventional wet processes, but also demonstrates outstanding flexibility, even when the entire film is folded. This could be attributed to the robustly weld-like wire-to-wire junction of Ag NWs, which enhances its mechanical characteristics. The results demonstrated the feasibility of this alternative approach for the development of an effective low-power-consumption route for fabricating foldable transparent electrodes. Moreover, the results also indicated the practicability of applying this foldable transparent electrode in the fabrication of highly flexible and wearable optoelectronic devices.