Nanoscale Photoluminescence Manipulation in Monolithic Porous Silicon Oxide Microcavity Coated with Rhodamine‐Labeled Polyelectrolyte via Electrostatic Nanoassembling

Abstract

Porous silicon (PSi) is a promising material for future integrated nanophotonics when coupled with guest emitters, still facing challenges in terms of homogenous distribution and nanometric thickness of the emitter coating within the silicon nanostructure. Herein, it is shown that the nanopore surface of a porous silicon oxide (PSiO2) microcavity (MC) can be conformally coated with a uniform nm‐thick layer of a cationic light‐emitting polyelectrolyte, e.g., poly(allylamine hydrochloride) labeled with Rhodamine B (PAH‐RhoB), leveraging the self‐tuned electrostatic interaction of the positively‐charged PAH‐RhoB polymer and negatively‐charged PSiO2 surface. It is found that the emission of PAH‐RhoB in the PSiO2 MC is enhanced (≈2.5×) and narrowed (≈30×) at the resonant wavelength, compared with that of PAH‐RhoB in a non‐resonant PSiO2 reference structure. The time‐resolved photoluminescence analysis highlights a shortening (≈20%) of the PAH‐RhoB emission lifetime in the PSiO2 MC at the resonance versus off‐resonance wavelengths, and with respect to the reference structure, thereby proving a significant variation of the radiative decay rate. Remarkably, an experimental Purcell factor Fp = 2.82 is achieved. This is further confirmed by the enhancement of the photoluminescence quantum yield of the PAH‐RhoB in the PSiO2 MC with respect to the reference structure. Application of the electrostatic nanoassembling approach to other emitting dyes, nanomaterials, and nanophotonic systems is envisaged.

Lasing from Narrow Bandwidth Light-Emitting One-Dimensional Nanoporous Photonic Crystals

“…This, in turn, results in a practical suppression of lasing emission and dramatically worsens the stability of the lasing system due to degradation. However, these limitations can be overcome by physically separating the fluorophore molecules through encapsulation within macromolecular structures such as dendrimers, surfactants, and polyelectrolytes . Motivated by these results, we decided to engineer the properties of the light-emitting organic functional layer in 1D RhoB-NAA-GIFs by modifying the ratio SDS:RhoB and analyzing its effect on the lasing emission from these model PC structures.…”

“…This would further demonstrate that the origin of lasing emissions in RhoB-modified NAA-GIFs is associated with a dramatic reduction in the group velocity of pumping photons at that spectral region since both the position of the PSB in NAA-GIFs and its red edge blue-shift their position when the angle of excitation is increased with respect to the normal direction. The excited-state lifetime of a model RhoB-NAA-GIF and a reference rhodamine B-functionalized NAA featuring straight pores was investigated to gain further insights into the radiative and nonradiative decay kinetics. , …”

“…However, these limitations can be overcome by physically separating the fluorophore molecules through encapsulation within macromolecular structures such as dendrimers, surfactants, and polyelectrolytes. 52 Motivated by these results, we decided to engineer the properties of the light-emitting organic functional layer in 1D RhoB-NAA-GIFs by modifying the ratio SDS:RhoB and analyzing its effect on the lasing emission from these model PC structures. To this end, the concentration ratio ([SDS]:[RhoB]) was systematically varied and a total of 48 combinations of surfactant:fluorophore were analyzed (i.e., [SDS] = 0.5−20 mM and [RhoB] = 0.01−2 mM).…”

“…The excited-state lifetime of a model RhoB-NAA-GIF and a reference rhodamine B-functionalized NAA featuring straight pores was investigated to gain further insights into the radiative and nonradiative decay kinetics. 52,53 Time-resolved photoluminescence quantification of these structures was performed by the time-correlated single-photon counting (TCSPC) method. Photoluminescence decay profiles were fitted to a biexponential function to extract the short and long decay times (τ short and τ long ).…”

Tamm Plasmon Resonance as Optical Fingerprint of Silver/Bacteria Interaction

“…We selected this method because of its simplicity and availability of the instrumentation. Note that although in colloidal photonic crystals, interlayer and intralayer roughness is relatively high, this can be taken as an advantage for various applications that require infiltration of selected analytes and probes. ,− In our case, we reckon that roughness can be beneficial for depositing a corrugated silver layer, which eventually allows access to the TP mode from the outside. However, such a method comes with a disadvantage, as it relies on the manual sequential deposition of the silica/titania layers from the colloidal dispersions, implying that this technique leads inherently to a large batch-to-batch variability in terms of spectral response (see for instance Figure a,c).…”