Abstract
AbstractThe 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.
Highlights
These hot-carriers follow Fermi-Dirac distribution, which can again relax by electron–electron scattering processes such asThe light–matter interaction at the nanoscale induces the Auger transitions
The hybrid mode resulted in enhanced hot electron generation leading to increased photocatalytic reaction, as compared to non-hybrid LSPR excitation. We explore such waveguide-plasmon coupled systems fabricated with cost-efficient bottom-up approaches. metallic photonic crystal slabs (mPhCs) produced over a large macroscopic area by scalable laser interference lithography[38,39] and physical vapor deposition[40] show direct contact of the metallic nanobars to the adjoined semiconductor TiO2 waveguide
In the current study focused on plasmonic charge transfers in both mPhC and colloidal photonic crystal slabs (cPhCs) slabs, we are interested to observe the effect of direct and separated contact between metal/semiconductor junctions on plasmonic charge transfer mechanisms
Summary
These hot-carriers follow Fermi-Dirac distribution, which can again relax by electron–electron scattering processes such as. We introduce colloidal photonic crystal slabs (cPhCs) toward exploring hot-electron based charge transfer mechanisms by using colloidally grown gold nanoparticles (AuNPs) with undesired isolating ligand shell (2 nm) These AuNPs are arranged in form of dimer chains[31,41] via directed self-assembly[42] methods that form the plasmonic grating component of the cPhC slabs. Such cPhCs have been recently explored by us for sensing application and linewidth control.[38] In the current study focused on plasmonic charge transfers in both mPhC and cPhC slabs, we are interested to observe the effect of direct and separated contact between metal/semiconductor junctions on plasmonic charge transfer mechanisms Both mPhCs and cPhCs (see schematics in Figure 1a) have been optically characterized via steady-state transmittances as well as transient ultrafast measurements. This is an important step toward optoelectronic device development, which should turn the ligand shell barrier into an advantage in the future
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