Plasmonic Charge Transfers in Large‐Scale Metallic and Colloidal Photonic Crystal Slabs

Abstract

The challenges in plasmonic charge transfer on a large‐scale and low losses are systematically investigated by optical designs using 1D‐plasmonic lattice structures. These plasmonic lattices are used as couplers to guide the energy in an underneath sub‐wavelength titanium dioxide layer, resulting in the photonic crystal slabs. So far, photodetection is possible at energy levels close to the semiconductor bandgap; however, with the observed hybrid plasmonic–photonic modes, other wavelengths over the broad solar spectrum can be easily accessed for energy harvesting. The photo‐enhanced current is measured locally with simple two‐point contact on the centimeter‐squared nanostructure by applying a bias voltage. As lattice couplers, interference lithographically fabricated conventional gold grating provides an advantage in fabrication; this optical concept is extended for the first time toward colloidal self‐assembled nanoparticle chains to make the charge injection accessible for large‐scale at reasonable costs with possibilities of photodetection by electric field vectors both along and perpendicular to the grating lines. To discuss the bottleneck of unavoidable isolating ligand shell of nanoparticles in contrast to the directly contacted nanobars, polarization‐dependent ultrafast characterizations are carried out to study the charge injection processes in femtosecond resolution.

Nanoimprint Lithography Facilitated Plasmonic‐Photonic Coupling for Enhanced Photoconductivity and Photocatalysis

“…Figure S9a‐iii, Supporting Information further provides direct proof of meeting the GMR condition through the electric field distribution ( ) similar to conventional GMR cases under TM polarization. Note, that unlike the previous demonstration of hybridization [ 43,44 ] using longitudinal plasmonic chain modes, [ 56 ] the novelty of the present work lies in introducing transverse plasmonic chain modes into the hybridization picture. Figures S9 and S10, Supporting Information show these two dominant resonances of localized surface plasmon resonance (LSPR) and GMR under different cross‐sections of the 3D electromagnetic simulation.…”

“…Figure a shows a schematic illustration of the targeted structure with assembled NP chains over a thin film of semiconducting TiO 2 layer, coated on a glass substrate. Such hybrid chains on a semiconductor waveguide have been recently explored by Sarkar et al, [ 43,44 ] where the particle chains were arranged within additional photoresist grating channels, patterned on the TiO 2 layer through interference lithography. [ 43 ] While the structure could be achieved in a straightforward assembly technique, it had a major drawback of the presence of additional photoresist layers as a barrier to the charge transfer processes.…”

“…In our previous study, we used a prefabricated dielectric grating to assemble 1D colloid grating via CAPA toward achieving hybrid modes. [ 43–45 ] In contrast, here, to the best of our knowledge, we report waveguide‐plasmon polaritons (WPP) excited for the first time by a purely colloidal 1D lattice printed on TiO 2 slab waveguide via NIL on a centimeter scale. High‐quality optical modes are achieved with a narrow line‐width of 10 nm as compared to their EBL fabricated counterpart.…”

“…Huang et al recently proved that hybridized WPP modes can enhance hot electron generation, finally resulting in greatly accelerated reduction conversion at a low illumination intensity. [ 52 ] Contrary to previous studies, [ 44,51 ] we have excited the Au/TiO 2 interface with an off‐normal excitation of 15° angle of incidence (AOI) since the plasmonic catalysis has a strong polarization dependency [ 49 ] showing enhanced photocatalytic activity when the polarization direction is perpendicular to the Au/TiO 2 interface. [ 49 ] Accordingly, we have used the MO dye oxidation as a probe reaction to study the hybrid WPP‐induced catalysis.…”

Exploring Plasmonic Resonances Toward “Large‐Scale” Flexible Optical Sensors with Deformation Stability

“…Thus, boosted with the established theoretical analysis and easily approachable fabrication means, one can successfully design an advanced class of functional materials to set a new paradigm of flexible and large‐scale plasmonic and optoelectronic devices with applications in energy harvesting. [ 33 ]…”