Molecular Polaritons Generated from Strong Coupling between CdSe Nanoplatelets and a Dielectric Optical Cavity

Enhanced delocalization is beneficial for absorbing molecules in organic solar cells, and in particular bilayer devices, where excitons face small diffusion lengths as a barrier to reaching the charge-generating donor–acceptor interface. As hybrid light–matter states, polaritons offer exceptional delocalization which could be used to improve the efficiency of bilayer organic photovoltaics. Polariton delocalization can aid in delivering excitons to the donor–acceptor interface, but the subsequent charge transfer event must compete with the fast decay of the polariton. To evaluate the viability of polaritons as tools to improve bilayer organic solar cells, we studied the decay of the lower polariton in three cavity systems: a donor only, a donor–acceptor bilayer, and a donor–acceptor blend. Using several spectroscopic techniques, we identified an additional decay pathway through charge transfer for the polariton in the bilayer cavity, demonstrating charge transfer from the polariton is fast enough to outcompete the decay to the ground state.

supporting

confidence: 92%

Polariton Decay in Donor–Acceptor Cavity Systems

Delpo

Khan

Park

et al. 2021

“…Despite the recent progress in the development of high quality-factor Fabry-Pérot cavities, optical microcavities are generally lossy. The typical values of cavity losses for a Fabry-Pérot cavity is in the range of 5–100 meV. ,− However, we expect the cavity loss will further assist the dynamical caging effect, because the cavity loss can be modeled with an additional dissipative noncavity bath coupled to the cavity mode . With such an additional bath coupled to the cavity mode, one should expect an increase of the dissipation from the reactive molecule, leading to the further reduction of reactive flux.…”

Section: Reaction Rate Constantmentioning

confidence: 99%

Theory of Mode-Selective Chemistry through Polaritonic Vibrational Strong Coupling

Mandal

Huo

2021

Self Cite

Recent experiments have demonstrated remarkable mode-selective reactivities by coupling molecular vibrations with a quantized radiation field inside an optical cavity. The fundamental mechanism behind such effects, on the other hand, remains elusive. In this work, we provide a theoretical explanation of the basic principle of how cavity frequency can be tuned to achieve mode-selective reactivities. We find that the dynamics of the radiation mode leads to a cavity frequency-dependent dynamical caging effect of a reaction coordinate, resulting in suppression of the rate constant. In the presence of competitive reactions, it is possible to preferentially cage a reaction coordinate when the barrier frequencies of competing reactions are different, resulting in a selective slow down of a given reaction. Our theoretical results illustrate the cavity-induced mode-selective chemistry through polaritonic vibrational strong couplings, revealing the fundamental mechanism for changing chemical selectivities through cavity quantum electrodynamics.

“…Polaritons are quasi-particles resulting from the coupling of a dipolar oscillation with electromagnetic waves. , This coupling leads to strongly confined local fields, with polariton wavelengths far smaller than the free-space wavelength of the electromagnetic wave . Several types of polaritons have been characterized, including plasmon polaritons, exciton polaritons, and phonon polaritons (PhPs). − This strong confinement can be used in SERS enhancement, driving reactions, sensor, hyperlensing, and other applications. − In strongly anisotropic materials where the ordinary and extraordinary dielectric functions have opposite signs, hyperbolic PhPs (HPhPs) propagate at fixed angles with arbitrarily large wavevectors throughout the material. − These hyperbolic modes are accessible through the engineering of artificial metamaterials but are also observed naturally in hexagonal boron nitride (h-BN) and boron nitride nanotubes (BNNTs). − BNNTs therefore act as a model system to understand bidirectional propagation of HPhPs in 1-D systems, with the first hyperbolic mode most extensively studied so far …”

mentioning

confidence: 99%

Fabry–Pérot Phonon Polaritons in Boron Nitride Nanotube Resonators

Phillips

Lai

Walker

2021

Phonon polaritons (PhPs) offer extreme confinement of optical fields and strong dispersion in the mid-infrared spectral region. To study the propagation and interference of PhPs in a 1-D system, we employ scattering scanning near-field optical microscopy (s-SNOM), analytical, and computational techniques to describe the resonance behavior observed in boron nitride nanotubes (BNNTs). In BNNTs of a sufficiently small length, the reflected standing waves from both terminals strongly interfere with one another, leading to large constructive enhancement at select wavelengths through the Fabry−Peŕot interference. This 1-D nanoresonant behavior illustrates methods to increase and localize field strength at positions on a BNNT nanotube.