Beibei Zeng

Polymeric photovoltaics with various metallic plasmonic nanostructures

Broadband light absorption enhancement is numerically investigated for the active light harvesting layer of an organic photovoltaic (OPV), which consists of a blend of poly(3-hexylthiophene) (P3HT) and the fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester (PCBM). Periodic plasmonic nanostructures placed above and below the active layer incorporate Ag, Al, Au, or a combination of two different metals. Three dimensional (3D) full-field electromagnetic simulations are applied to determine the effect of varying the metal employed in the plasmonic nanostructures on the absorption enhancement of the OPV. In addition, the geometric parameters (e.g., film thickness, period, and diameter) of the symmetrically distributed top and bottom metal (Ag, Al, or Au) nanostructures were varied to optimize the device structure and delineate the mechanism(s) leading to the absorption enhancement. A spectrally broadband, polarization-insensitive, and wide-angle absorption enhancement is obtained using a double pl...

Rapid and highly sensitive detection using Fano resonances in ultrathin plasmonic nanogratings

We developed a nanoplasmonic sensor platform employing the extraordinary optical properties of one-dimensional nanogratings patterned on 30 nm-thick ultrathin Ag films. Excitation of Fano resonances in the ultrathin Ag nanogratings results in transmission spectra with high amplitude, large contrast, and narrow bandwidth, making them well-suited for rapid and highly sensitive sensing applications. The ultrathin nanoplasmonic sensor chip was integrated with a polydimethylsiloxane microfluidic channel, and the measured refractive index resolution was found to be 1.46 × 10−6 refractive index units with a high temporal resolution of 1 s. This compares favorably with commercial prism-based surface plasmon resonance sensors, but is achieved using a more convenient collinear transmission geometry and a significantly smaller sensor footprint of 50 × 50 μm2. In addition, an order-of-magnitude improvement in the temporal and spatial resolutions was achieved relative to state-of-the-art nanoplasmonic sensors, for com...

Transparent electrodes based on two-dimensional Ag nanogrids and double one-dimensional Ag nanogratings for organic photovoltaics

Abstract. The optical and electrical properties of optically thin one-dimensional (1-D) Ag nanogratings and two-dimensional (2-D) Ag nanogrids are studied, and their use as transparent electrodes in organic photovoltaics is explored. A large broadband and polarization-insensitive optical absorption enhancement in the organic light-harvesting layers is theoretically and numerically demonstrated using either single-layer 2-D Ag nanogrids or two perpendicular 1-D Ag nanogratings, and is attributed to the excitation of surface plasmon resonances and plasmonic cavity modes. Total photon absorption enhancements of 150% and 200% are achieved for the optimized single-layer 2-D Ag nanogrids and double (top and bottom) perpendicular 1-D Ag nanogratings, respectively.

Plasmonic electrodes for organic photovoltaics: polarization-independent absorption enhancement

We systematically investigate the optical and electrical properties of ultrathin two-dimensional (2D) Ag nanogratings (NGs), and explore their use as plasmonic transparent conducting electrodes in molecular organic photovoltaics (OPVs). A large broadband and polarization-insensitive optical absorption enhancement in the CuPc (copper phthalocyanine): PTCBI (perylene tetracarboxylic bisbenzimidazole) active light-harvesting layers is demonstrated using ultrathin 2D Ag NGs, and is attributed to the excitation of surface plasmon resonances and plasmonic cavity modes.

Absorption enhancement in thin-film organic photovoltaics with double plasmonic structures

Broadband light absorption enhancement is numerically investigated for double plasmonic structures in thin-film organic photovoltaics. Due to the combined excitation of different Surface Plasmon modes, the absorption enhancement of about 67% is obtained.

Differentiating surface and bulk interactions in nanoplasmonic interferometric sensor arrays

We present a nanoplasmonic interferometric sensor platform that can differentiate the adsorption of a thin protein layer on the sensor surface from bulk refractive index changes, exploiting the different penetration depths of multiple SPPs.

Ultrathin plasmonic subtractive color filters

We present the design and demonstration of ultra-thin plasmonic color filters, providing a powerful approach for subtractive color filtering with high spatial resolution and ultra-compact architectures on sub-micrometer scales.

Leak-free focusing of propagating surface plasmon waves using non-symmetric double nanorings

Plasmonic leak-free focusing is proposed using nonsymmtric double nanorings. A single focal spot could be obtained at the geometric center through the constructive interference of two anti-propagating surface plasmon waves by breaking the geometrical symmetry.

Thin-film organic photovoltaics with double plasmonic nanostructures: The metal effect

Broadband light absorption enhancement is numerically investigated for double plasmonic nanostructures in thin-film organic photovoltaics (OPVs) using Ag, Al, and Au. A spectrally broadband, polarization-insensitive, and wide-angle absorption enhancement in the organic layer is predicted.