Fabrication of ZnO nano-structures using UV nanoimprint lithography of a ZnO nano-particle dispersion resin

Jo, Han Byeol; Byeon, Kyeong Jae; Lee, Heon; Kwon, Moo Hyun; Choi, Kyung Woo

doi:10.1039/c2jm32509h

Cited by 28 publications

(17 citation statements)

References 24 publications

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“…Figure 2 a,d shows, respectively, the SEM and AFM images obtained of the flat mesoporous ZnO layer produced on glass by spin coating and annealing. In Figure 2 b,e, we see that that the subsequent UV-NIL process successfully replicates the pattern of the master stamp with a high degree of fidelity; however, the pattern size is shrunk due to the solvent in the ZnO NP dispersion resin being absorbed into the PDMS mold and removed during the UV-NIL process [ 17 ]. Thus, in the mesoporous ZnO pattern, the diameter and height of the micro-cone-shaped structure are reduced to 2.2 and 0.7 μm, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…This is based on the fact that a large portion of incident light is reflected at the interface formed between layers with a large difference in refractive index, which can be minimized by introducing an additional layer with an intermediate refractive index to create a more gradual change. In this study, we formed mesoporous ZnO pattern on glass substrates for light-scattering effect by using ultraviolet nanoimprint lithography (UV-NIL) [ 17 , 18 ]. The mesoporous ZnO pattern provides strong scattering of light since it has two light-scattering centers.…”

Section: Introductionmentioning

confidence: 99%

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Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

Kim

et al. 2014

Nanoscale Res Lett

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To provide a front transparent electrode for use in highly efficient hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, porous flat layer and micro-patterns of zinc oxide (ZnO) nanoparticle (NP) layers were prepared through ultraviolet nanoimprint lithography (UV-NIL) and deposited on Al-doped ZnO (AZO) layers. Through this, it was found that a porous micro-pattern of ZnO NPs dispersed in resin can optimize the light-trapping pattern, with the efficiency of solar cells based on patterned or flat mesoporous ZnO layers increased by 27% and 12%, respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

Kim

et al. 2014

Nanoscale Res Lett

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“…Especially imprinting with negative polydimethylsiloxane (PDMS) molds and ultraviolet (UV) curable materials, soft embossing has emerged as a novel technology for polymer micro-structures fabrication [16]- [18]. Compared with other micro-structure fabrication technologies including the injection molding [19], diamond tooling [20], hot embossing [21], and laser processing [22], soft embossing is simple and highly efficient.…”

Section: Introductionmentioning

confidence: 99%

Electrically Controllable Liquid Crystal Component for Efficient Light Steering

et al. 2015

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In this paper, we present an electrically controllable microoptical component for light beam steering and light intensity distribution built on the combination of nematic liquid crystal (LC) and polymer microprisms. Polymer microprism arrays are fabricated using soft embossing with elastic polydimethylsiloxane molds and ultraviolet curable resins. Surface profiling measurements show that the dimensions of the replicated prisms closely approximate those of the master prism. Two different LC alignment techniques were employed: hybrid rubbing alignment and obliquely evaporated SiO 2 alignment, both of which result in proper alignment of the LC molecules along the prism groove direction. The operation voltage of the LC components is relatively low (10 V rms ). The steering angle of a green laser beam was experimentally studied as a function of applied voltage, and a steering range of 3 was found. The active LC components also effectively deflect a collimated white light beam over a steering angle of about 2 with an efficiency of 27%-33%. All the optical measurements are in agreement with theoretical calculations based on Snell's law.

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“…17,18 However, the fabrication of nanoscale-patterned sapphire substrate (NPSS) generally requires electron-beam lithography and nanoimprint techniques, which makes the advantage of performance improvement to be offset by the increased fabrication cost. 19,20 Nanosphere lithography (NSL) technique, which is based on a monolayer-colloidal-crystal (MCC) templating strategy, has been employed as an economic way to construct largearea and highly ordered nanostructures, 21,22 which have demonstrated important applications in the optoelectronic devices. [23][24][25][26] Recently, NSL has been utilized to prepare NPSS with the advantage of large-area fabrication and flexible tuning of the feature size.…”

Section: Introductionmentioning

confidence: 99%

Improved performance of GaN-based light emitting diodes with nanopatterned sapphire substrates fabricated by wet chemical etching

Yan

Dong

Shan

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The authors present a facile approach to the fabrication of nanopatterned sapphire substrates (NPSS) with concave pyramid structure by a wet etching method. The silica wet-etching mask on the sapphire substrate was prepared by using a colloidal monolayer templating strategy. NPSS with two different periods were prepared by employing 660 and 900 nm polystyrene colloidal spheres. Light emitting diode (LED) structure was epitaxially grown on the NPSS by the metal-organic chemical vapor deposition method. Both structural and optoelectronic properties of LEDs grown on flat sapphire substrate and NPSS were demonstrated and compared in detail. The calculations based on x-ray rocking curves revealed that the threading dislocation densities (TDDs) were decreased and the crystalline quality of epitaxial GaN film was improved when NPSS was used. Furthermore, the decrease in the edge TDDs was more prominent than that in the screw TDDs, which could be explained by the dislocation annihilation mechanism. The LEDs grown on 660- and 900-nm-NPSS exhibited 48% and 56% enhancement in light output power compared to that of a conventional LED on a flat sapphire substrate, arising from the nanoscale patterns in the sapphire which allowed more light to reflect from sapphire substrate onto the top direction.

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Fabrication of ZnO nano-structures using UV nanoimprint lithography of a ZnO nano-particle dispersion resin

Cited by 28 publications

References 24 publications

Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

Electrically Controllable Liquid Crystal Component for Efficient Light Steering

Improved performance of GaN-based light emitting diodes with nanopatterned sapphire substrates fabricated by wet chemical etching

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