Development of a cost effective surface-patterned transparent conductive coating as top-contact of light emitting diodes

Abstract

Edge effect enhanced electron field emission in top assembled reduced graphene oxide assisted by amorphous CNT-coated carbon cloth substrate AIP Advances 3, 012115 (2013); 10.1063/1.4789409Theoretical and experimental approach on dielectric properties of ZnO nanoparticles and polyurethane/ZnO nanocomposites J.Sol-gel process has been used to form indium zinc oxide films using an optimized combination of zinc to indium concentration in the precursor solutions. Different structures, like one (1D) and two-dimensional (2D) gratings and diffractive optical elements (DOEs) in the form of Fresnel lens are fabricated on the film surface of proposed top metal contact of LED by imprint soft lithography technique. These structures can enhance the LED's light extraction efficiency (LEE) or can shape the output beam pattern, respectively. Several characterizations are done to analyze the material and structural properties of the films. The presence of 1D and 2D gratings as well as DOEs is confirmed from field emission scanning electron and atomic force microscopes analyses. Although, X-ray diffraction shows amorphous nature of the film, but transmission electron microscopy study shows that it is nano crystalline in nature having fine particles ($8 nm) of hexagonal ZnO. Shrinkage behaviour of gratings as a function of curing temperature is explained by Fourier transform infra-red spectra and thermo gravimetric-differential thermal analysis. The visible transmission and sheet resistance of the sample are found comparable to tin doped indium oxide (ITO). Therefore, the film can compete as low cost substitute of ITO as top metal contact of LEDs. V C 2014 AIP Publishing LLC. [http://dx.

Further enhancement of light extraction efficiency from light emitting diode using triangular surface grating and thin interface layer

“…It has been also shown in [26] that periodic grating structures are better than aperiodic structures for flux enhancement. The sol-gel technique developed for producing thin films of IZO [17], followed by soft lithography, can be used to fabricate the triangular gratings. The flowchart of the entire process is shown in Fig.…”

“…The corresponding author and his group have recently developed a sol-gel technique to form an indium-zinc-oxide (IZO)-based thin film transparent conducting oxide (TCO) that can act as a low-cost top metal contact of an LED [17]. Its surface patterning is done to improve the LEE of the LED.…”

Indium Oxide Based Nanomaterials: Fabrication Strategies, Properties, Applications, Challenges and Future Prospect

“…In addition, some sol-gel based nanostructured IO thin films with their area of applications are highlighted in Table 2. [4,46,48,49], respectively).…”

“…[2,8,10]. On the other hand, different nanostructured IO based bulk nanomaterials such as nanosheets, nanowires, nanoparticles, quantum dots, single crystals are found to have potential applications [8,[11][12][13].…”

Optimization by a genetic algorithm of the light-extraction efficiency of a GaN light-emitting diode

“…[1,2,3] Many efforts actually focus on finding an efficient structuration of the surface in order to enhance the extraction of light. [4,5,6,7,8,9,10] Diffusion by surface roughness for example will open new optical channels for the extraction of light. [11] Some structurations specifically aim at achieving a graded refractive index at the surface in order to reduce total internal reflections.…”