The second issue of Advanced Optical Materials as an independent journal is now online, including twelve excellent research articles covering all aspects of light-matter interactions.
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Color Filters: Plasmonic Color Filter and its Fabrication for Large-Area Applications (Advanced Optical Materials 2/2013) (page 109)Yun Seon Do, Jung Ho Park, Bo Yeon Hwang, Sung-Min Lee, Byeong-Kwon Ju and Kyung Cheol ChoiArticle first published online: 22 FEB 2013 | DOI: 10.1002/adom.201370010
A plasmonic color filter (PCF) containing a metallic nanohole array is described by B.-K. Ju, K. C. Choi, and co-workers. This new PCF can be fabricated on an extremely large scale compared to the currently available alternatives, and the process can be adapted to create a flexible product. This is possible by using laser interference lithography based on Lloyd’s mirror, as shown in the bottom left of the front cover image. The metal layer is positioned between two dielectric layers (which are different from the substrate), allowing high transmission. The filtering of all primary colors (red, green, and blue) is demonstrated on page 133.
Inside Front Cover: Electrochemiluminescence: Alternating-Current-Driven, Color-Tunable Electrochemiluminescent Cells (Advanced Optical Materials 2/2013) (page 110)Taiki Nobeshima, Masaru Nakakomi, Kazuki Nakamura and Norihisa Kobayashi
Article first published online: 22 FEB 2013 | DOI: 10.1002/adom.201370011
A novel method for tuning the color of electrochemiluminescence (ECL) is investigated by N. Kobayashi and co-workers. The emission color from a single AC-driven ECL cell containing two different luminescent molecules is tuned by modulating the applied frequency. As shown on page 144, yellow emission is observed from an ECL cell to which AC is applied at 900–1800 Hz, whereas the emission becomes white when the frequency is adjusted below 800 Hz.
Back Cover: Microresonators: Coupling Resonant Modes of Embedded Dielectric Microspheres in Solution-Processed Solar Cells (Advanced Optical Materials 2/2013) (page 194)Agustín Mihi, Maria Bernechea, Dominik Kufer and Gerasimos Konstantatos
Article first published online: 22 FEB 2013 | DOI: 10.1002/adom.201370012
The unique way in which light resonates in microspheres is applied by G. Konstantatos and co-workers on page 139 to enhance the light-harvesting efficiency of a solution-processed PbS quantum dot–TiO2 heterojunction. Depending on the relative position of the silica sphere monolayer with respect to the PbS–TiO2 bilayer, different resonant modes can be coupled into the PbS absorbing layer, boosting the solar cell performance. The cover depicts a cross-section of a microsphere layer completely embedded within PbS quantum dots on the nano crystalline TiO2 film. The PbS quantum dot layer and the nano crystalline titania layer are coloured pink and violet, respectively.
Organic Nanofibers: Extending the Lasing Wavelength Coverage of Organic Semiconductor Nanofibers by Periodic Organic–Organic Heteroepitaxy (Advanced Optical Materials 2/2013) (page 116)Francesco Quochi, Günther Schwabegger, Clemens Simbrunner, Francesco Floris, Michele Saba, Andrea Mura, Helmut Sitter and Giovanni Bongiovanni
Article first published online: 22 FEB 2013 | DOI: 10.1002/adom.201370015
Thin films of organic epitaxial nanofibers represent a viable strategy towards the realization of effective organic semiconductor lasers. Outlined on page 117, a novel approach based on organic-organic heteroepitaxy is taken by F. Quochi et al. to endow the nanofibers with a highly functional oligomer heterostructure, enabling random lasing with low thresholds in multiple bands across the visible spectrum.
Extending the Lasing Wavelength Coverage of Organic Semiconductor Nanofibers by Periodic Organic–Organic Heteroepitaxy (pages 117–122)Francesco Quochi, Günther Schwabegger, Clemens Simbrunner, Francesco Floris, Michele Saba, Andrea Mura, Helmut Sitter and Giovanni Bongiovanni
Article first published online: 12 FEB 2013 | DOI: 10.1002/adom.201200005
Organic–organic heteropitaxy based on alternating and periodic deposition of para-sexiphenyl and alpha-sexithiophene on muscovite mica enables the fabrication of organic semiconductor nanofibers capable of random lasing with multiband emission and operating in the monomolecular recombination regime at room temperature.
Shrink-to-fit Plasmonic Nanostructures (pages 123–127)A. S. Urban, M. Fedoruk, S. Nedev, A. Lutich, T. Lohmueller and J. Feldmann
Article first published online: 6 FEB 2013 | DOI: 10.1002/adom.201200031
Plasmonic nanostructures are generated by substrate heating. A polymer substrate decorated with clusters of gold particles is shrinking uniformly upon heating. The separation distance between individual nanoparticles is thereby reduced at the same time. The process is visible by a color change of the gold nanoparticle clusters due to plasmonic coupling.
Direct Optical Tuning of the Terahertz Plasmonic Response of InSb Subwavelength Gratings (pages 128–132)Liyuan Deng, Jinghua Teng, Hongwei Liu, Qing Yang Wu, Jie Tang, Xinhai Zhang, Stefan A. Maier, Kim Peng Lim, Chun Yong Ngo, Soon Fatt Yoon and Soo Jin Chua
Article first published online: 6 FEB 2013 | DOI: 10.1002/adom.201200032
Direct optical tuning of the THz plasmonic response of InSb subwavelength gratings is demonstrated experimentally. By injecting carriers into the semiconductor plasmonic material optically, the resonant frequency of the grating structure blue shifts, leading to tuning of the THz transmission. Potential modulation speeds up to the GHz regime are characterized by carrier lifetime studies.
Plasmonic Color Filter and its Fabrication for Large-Area Applications (pages 133–138)Yun Seon Do, Jung Ho Park, Bo Yeon Hwang, Sung-Min Lee, Byeong-Kwon Ju and Kyung Cheol Choi
Article first published online: 12 FEB 2013 | DOI: 10.1002/adom.201200021
A large plasmonic color filter (PCF) is fabricated via a simple and cost-effective method. The aluminum surfaces are surrounded by lithium fluoride with the penetration depth scaled to match the surface plasmon modes efficiently, resulting in high transmittance. All filters of primary colors show peak transmittance at the wavelength regions corresponding to those determined in calculations.
Coupling Resonant Modes of Embedded Dielectric Microspheres in Solution-Processed Solar Cells (pages 139–143)Agustín Mihi, Maria Bernechea, Dominik Kufer and Gerasimos Konstantatos
Article first published online: 12 FEB 2013 | DOI: 10.1002/adom.201200015
Resonant modes of dielectric microspheres are coupled into solution processed solar cells, resulting in an enhancement in photocurrent. Three different locations of the sphere monolayer within the absorbing PbS quantum dot layer are investigated in an attempt to maximize the number of resonant modes leaked into the PbS.
Alternating-Current-Driven, Color-Tunable Electrochemiluminescent Cells (pages 144–149)Taiki Nobeshima, Masaru Nakakomi, Kazuki Nakamura and Norihisa Kobayashi
Article first published online: 15 FEB 2013 | DOI: 10.1002/adom.201200056
Color-tuning of electrochemiluminescence (ECL) emission by frequency modulation of the alternating-current (AC) applied to a single ECL cell containing two different luminescent molecules is demonstrated. Yellow light emission is observed for 1000 Hz AC, while white light is emitted when the frequency is switched to 300 Hz (figure). The ECL cells are simply fabricated by sandwiching an electrolyte solution between transparent electrodes.
Split Ring Resonators: Enhanced Raman Scattering of Graphene using Arrays of Split Ring Resonators (Advanced Optical Materials 2/2013) (page 150)George Sarau, Basudev Lahiri, Peter Banzer, Priti Gupta, Arnab Bhattacharya, Frank Vollmer and Silke Christiansen
Article first published online: 22 FEB 2013 | DOI: 10.1002/adom.201370016
Graphene on split ring resonator arrays, as described on page 151 by G. Sarau et al., represents a novel and tunable platform for gaining a basic understanding of surface-enhanced Raman scattering (SERS) effects. The Raman enhancement of graphene proves the strong plasmonic coupling between graphene and the metamaterial resonances excited by incident, photoluminescence, and Raman light. This opens the way towards an advanced SERS substrate for high-sensitivity detection of molecules attached to graphene.
Enhanced Raman Scattering of Graphene using Arrays of Split Ring Resonators (pages 151–157)George Sarau, Basudev Lahiri, Peter Banzer, Priti Gupta, Arnab Bhattacharya, Frank Vollmer and Silke Christiansen
Article first published online: 12 FEB 2013 | DOI: 10.1002/adom.201200053
Up to 75-fold SERS enhancements per area for graphene monolayers transferred over arrays of split ring resonators are measured. This demonstrates the strong plasmonic coupling between graphene and resonances of various strengths excited in the split ring resonator (SRR) patterns by the incident, photoluminescence, and Raman light. The graphene/SRR platform can be used as an advanced SERS substrate for high sensitivity detection of molecules attached to graphene.
Optical Absorption Properties of Semiconducting Nanostructures with Different Shapes (pages 158–166)Hilal Cansizoglu, Mehmet F. Cansizoglu, Miria Finckenor and Tansel Karabacak
Article first published online: 12 FEB 2013 | DOI: 10.1002/adom.201200018
Experimental and theoretical investigation of optical absorption properties of indium sulfide (In2S3) nanostructure arrays of rods, screws, springs, zigzags and tilted rods are presented. Measurements show that the optical absorption of semiconducting nanostructures can strongly depend on their shape. Spring, screw, and tapered-rod shapes can introduce a uniform distribution of diffracted light intensity and stronger absorption, indicating an enhanced diffuse light scattering.
Ambipolar Transporting 1,2-Benzanthracene Derivative with Efficient Green Excimer Emission for Single-Layer Organic Light-Emitting Diodes (pages 167–172)Lian Duan, Juan Qiao, Yongduo Sun, Deqiang Zhang, Guifang Dong, Liduo Wang and Yong Qiu
Article first published online: 12 FEB 2013 | DOI: 10.1002/adom.201200024
A highly efficient single-layer organic light-emitting diode (OLED) with green excimer emission is demonstrated using 7,12-bis-[4-(2,2-diphenylvinyl)-phenyl]benzanthracene as the active layer. As holes can perform intermolecular hopping to similar spatial extents between the adjacent benzanthracene moieties, well-balanced hole and electron mobilities higher than 10−3 cm2/Vs are achieved, facilitating high-performance single-layer OLEDs.
Intrinsic and Extrinsic Fluorescence in Carbon Nanodots: Ultrafast Time-Resolved Fluorescence and Carrier Dynamics (pages 173–178)Xiaoming Wen, Pyng Yu, Yon-Rui Toh, Xiaotao Hao and Jau Tang
Article first published online: 12 FEB 2013 | DOI: 10.1002/adom.201200046
Fluorescent carbon nanodots consist of two spectral overlapped bands. The intrinsic band exhibits a small bandwidth at 459 nm and is attributed to the sp2 nano domains. The extrinsic originates from the abundant carboxyl functional groups on the surface and thus exhibits much broader bandwidth, which results in excitation wavelength-dependent fluorescence.
ZnO p–n Homojunction Random Laser Diode Based on Nitrogen-Doped p-type Nanowires (pages 179–185)Jian Huang, Sheng Chu, Jieying Kong, Long Zhang, Casey M. Schwarz, Guoping Wang, Leonid Chernyak, Zhanghai Chen and Jianlin Liu
Article first published online: 22 FEB 2013 | DOI: 10.1002/adom.201200062
An electrically pumped ZnO homojunction random laser diode based on nitrogen-doped p-type ZnO nanowires and an n-type ZnO thin film is demonstrated. Random lasing peaks are evident in the electroluminescence spectra at the injection currents above the threshold pumping current. Far-field emission patterns of the random laser are taken by a commercial digital camera at different pumping currents.
Ultrathin Terahertz Planar Elements (pages 186–191)Dan Hu, Xinke Wang, Shengfei Feng, Jiasheng Ye, Wenfeng Sun, Qiang Kan, Peter J. Klar and Yan Zhang
Article first published online: 22 FEB 2013 | DOI: 10.1002/adom.201200044
An ultrathin planar lens composed of complementary V-shaped antennas in a 100 nm good film can focus 400 μm terahertz radiation and achieve imaging of an object. Each antenna can modify the phase of a second point source on the wavefront according to requirement. Experiment results provided a convincing demonstration for the design approach of various ultrathin planar optical elements.