Volumetric plasmonic resonator architecture for thin-film solar cells

Cataloged from PDF version of article.We propose and demonstrate a design concept of volumetric plasmonic resonators that relies on the idea of incorporating coupled layers of plasmonic structures embedded into a solar cell in enhanced optical absorption for surface-normal and off-axis angle configurations, beyond the enhancement limit of individual plasmonic layers. For a proof-of-concept demonstration in a thin-film organic solar cell that uses absorbing materials of copper phthalocyanine/perylene tetracarboxylic bisbenzimidazole, we couple two silver grating layers such that the field localization is further extended within the volume of active layers. Our computational results show a maximum optical absorption enhancement level of similar to 67% under air mass 1.5 global illumination considering both polarizations. (C) 2011 American Institute of Physics

Plasmonic backcontact grating for P3HT:PCBM organic solar cells enabling strong optical absorption increased in all polarizations

Cataloged from PDF version of article.In P3HT:PCBM based organic solar cells we propose and demonstrate numerically plasmonic backcontact grating architectures for strong optical absorption enhanced in both transverse-magnetic and transverse-electric polarizations. Even when the active material is partially replaced by the metallic grating (without increasing the active layer film thickness), we show computationally that the light absorption in thin-film P3HT:PCBM is increased by a maximum factor of similar to 21% considering both polarizations under AM1.5G solar radiation and over a half-maximum incidence angle of 45 degrees (where the enhancement drops to its half) compared to the same cell without a grating. This backcontact grating outperforms the typical plasmonic grating placed in PEDOT:PSS layer. (C)2011 Optical Society of America

Anisotropic Emission from Multilayered Plasmon Resonator Nanocomposites of Isotropic Semiconductor Quantum Dots

Cataloged from PDF version of article.We propose and demonstrate a nanocomposite localized surface plasmon resonator embedded into an artificial three-dimensional construction. Colloidal semiconductor quantum dots are assembled between layers of metal nanoparticles to create a highly strong plasmon-exciton interaction in the plasmonic cavity. In such a multilayered plasmonic resonator architecture of isotropic CdTe quantum dots, we observed polarized light emission of 80% in the vertical polarization with an enhancement factor of 4.4, resulting in a steady-state anisotropy value of 0.26 and reaching the highest quantum efficiency level of 30% ever reported for such CdTe quantum dot solids. Our electromagnetic simulation results are in good agreement with the experimental characterization data showing a significant emission enhancement in the vertical polarization, for which their fluorescence decay lifetimes are substantially shortened by consecutive replication of our unit cell architecture design. Such strongly plasmon-exciton coupling nanocomposites hold great promise for future exploitation and development of quantum dot plasmonic biophotonics and quantum dot plasmonic optoelectronics

HD-video streaming over an inexpensive in-building radio-over-MMF system

The need for indoor wireless connectivity is increasing, and conventional systems are getting congested in the radio spectrum. A promising solution is an indoor network consisting of many radio pico-cells fed via fiber. We propose a low-cost implementation by deploying Radio-over-Fiber techniques. The remote antenna contains only an optical-to-electrical conversion, and each pico-cell is fed by a residential gateway through a multi-mode fiber backbone. We characterize the physical layer and experimentally measure the Quality of Service (QoS). To evaluate its practical applicability, we assess the end-user perceived Quality of Experience (QoE) during HD-video streaming and its relation to QoS

Photocatalytic hybrid nanocomposites of metal oxide nanoparticles enhanced towards the visible spectral range

Cataloged from PDF version of article.We propose and demonstrate photocatalytic hybrid nanocomposites that co-integrate TiO(2) and ZnO nanoparticles in the same host resin to substantially enhance their combined photocatalytic activity in the near-UV and visible spectral ranges, where the intrinsic photocatalytic activity of TiO2 nanoparticles or that of ZnO nanoparticles is individually considerably weak For a comparative study, by embedding TiO(2) nanoparticles of ca. 6 nm and ZnO nanoparticles of ca. 40 nm in the sol-gel matrix of acrylic resin, we make thin film coatings of TiO(2)-ZnO nanoparticles (combination of TiO2 and ZnO, each with a mass ratio of 8.5%), as well as the composite films of TiO(2) nanoparticles alone (17.0%), and ZnO nanoparticles alone (17.0%), and a negative control group with no nanoparticles. For all of these thin films coated on polyvinyl chloride (PVC) polyester, we experimentally study photocatalytic activity and systematically measure spectral degradation (recovery obtained by photocatalytic reactions). This spectral characterization exhibits photodegradation levels of the contaminant at different excitation wavelengths (in the range of 310-469 nm) to distinguish different parts of optical spectrum where TiO(2) and ZnO nanopartides are individually and concurrently active. We observe that the photocatalytic activity is significantly improved towards the visible range with the use of TiO(2)-ZnO combination compared to the individual cases. Particularly for the excitation wavelengths of photochemical reactions longer than 400 nm, where the negative control group and ZnO nanoparticles alone yield no observable photodegradation level and TiO2 nanoparticles alone lead to a low photodegradation level of 14%, the synergic combination of TiO(2)-ZnO nanoparticles achieves a photodegradation level as high as 30%. Investigating their scanning electron microscopy (SEM), X-ray diffraction (XRD), and high resolution transmission electron microscopy (HRTEM), we present evidence of the heterostructure, crystallography, and chemical bonding states for the hybrid TiO(2)-ZnO nanocomposite films, in comparison to the films of only TiO(2) nanoparticles, only ZnO nanoparticles, and no nanoparticles. (C) 2011 Elsevier B.V. All rights reserved

Ultrafast laser patterning of organic/ inorganic thin-films for OLED / OPV applications

In organic electronics (OLED / OPV) fabrication, thin-film layers consisting of inorganic or inorganic-organic multilayered stack are crucial. Process optimization is challenging as the damage on the barrier layer can lead to the moisture and oxygen penetration into the stack resulting in degradation of the device. Various inorganic and organic thin films on a glass / inorganic-organic barrier substrates are patterned using 355 nm, 532 nm and 1064 nm picosecond laser pulses. The laser pulse interaction with thin films / barrier using static single pulse (determining thresholds) and dynamic patterning, has been optimized in terms of energy, frequency and pulse overlap.In organic electronics (OLED / OPV) fabrication, thin-film layers consisting of inorganic or inorganic-organic multilayered stack are crucial. Process optimization is challenging as the damage on the barrier layer can lead to the moisture and oxygen penetration into the stack resulting in degradation of the device. Various inorganic and organic thin films on a glass / inorganic-organic barrier substrates are patterned using 355 nm, 532 nm and 1064 nm picosecond laser pulses. The laser pulse interaction with thin films / barrier using static single pulse (determining thresholds) and dynamic patterning, has been optimized in terms of energy, frequency and pulse overlap.C