Engineering and Controlling Perovskite Emissions via Optical Quasi‐Bound‐States‐in‐the‐Continuum

Abstract

Metal halide perovskite quantum dots (PQDs) have emerged as promising materials due to their exceptional photoluminescence (PL) properties. A wide range of applications could benefit from adjustable luminescence properties, while preserving the physical and chemical properties of the PQDs. Therefore, post‐synthesis engineering has gained attention recently, involving the use of ion‐exchange or external stimuli, such as extreme pressure, magnetic and electric fields. Nevertheless, these methods typically suffer from spectrum broadening, intensity quenching or yield multiple bands. Alternatively, photonic antennas can modify the radiative decay channel of perovskites via the Purcell effect, with the largest wavelength shift being 8 nm to date, at an expense of fivefold intensity loss. Here, this work presents an optical nanoantenna array with polarization‐controlled quasi‐bound‐states‐in‐the‐continuum resonances, which can engineer and shift the photoluminescence wavelength over a ≈39 nm range and confers a 21‐fold emission enhancement of FAPbI3 perovskite QDs. The spectrum is engineered in a non‐invasive manner via lithographically defined antennas and the pump laser polarization at ambient conditions. This research provides a path toward advanced optoelectronic devices, such as spectrally tailored quantum emitters and lasers.

Dynamic Ultrastrong Coupling in a 2 nm Gap Plasmonic Cavity at the Sub-Picosecond Scale

“…Our findings suggest that time-resolved broadband TA experiments could provide the key spectral evolution information on underlying ultrastrong coupling phenomena of LSPRs for full metallic plasmonic cavity systems, and the configuration of NPiT could be a novel platform to study the dynamical Casimir effect with nanogap resonators at room temperature. In addition, this time-resolved technique can be readily applied to measure the emission characteristic of quantum emitters being coupled to dielectric nanoantennas with either Mie resonance or bound-states-in-the-continuum. , …”

“…In addition, this time-resolved technique can be readily applied to measure the emission characteristic of quantum emitters being coupled to dielectric nanoantennas with either Mie resonance or bound-states-in-the-continuum. 43,44 ■ ASSOCIATED CONTENT * sı Supporting Information…”

All‐Dielectric SERS Metasurface with Strong Coupling Quasi‐BIC Energized by Transformer‐Based Deep Learning

“…Second, when the order of field enhancement on the metasurface is required, one should provide the design parameters properly, such as the incident angle, transmittance, and the corresponding geometry sizes for the generation of strong-coupling Q-BIC. Currently, various deep learning technologies are blooming for scientific discovery and intelligent design, such as artificial neural networks and chat generative pre-trained transformer (ChatGPT), [40][41][42] which should have the potential to be used as state-of-the-art tools of optical design to investigate such kind of metasurfaces. [43][44][45][46][47][48][49][50][51][52][53][54][55][56] In view of these two aspects, we propose a deep learning scheme based on the transformer model to boost the design of the all-dielectric SERS metasurface, which consists of the forward neural network (FNN) and inverse neural network (INN), as shown in Figure 4.…”

Selective Perturbation of Eigenfield Enables High-Q Quasi-Bound States in the Continuum in Dielectric Metasurfaces

“…The Q -factor of quasi-BICs maintains an inverse square relation to the asymmetric parameters under small perturbations, which arise from asymmetries induced by the structure or the permittivity (refractive index). In a series of theoretical and experimental works since then, the scalar laws of −2 ( Q ∝ α –2 ) or nearly −2 for the Q -factor of quasi-BICs excited by breaking the structural symmetry have been richly confirmed. − Nowadays, these quasi-BICs resonators with high Q -factor are used in applications such as nonlinear harmonic generations, ,,,, biosensing, , lasers, − strong coupling effects, luminescence enhancement, , optical vortex, , optical absorption, ,, and photocatalysis . However, the Q -factor of these quasi-BICs is highly sensitive to the degree of asymmetry, and the achievement of high Q -factor resonances implies that very small perturbation parameters need to be obtained, and hence, precise and reproducible control of the asymmetry is key.…”