Light Emission from Vibronic Polaritons in Coupled Metalloporphyrin-Multimode Cavity Systems

Abstract

In this study, we explore how one can use cavity polariton formation and a non-Condon vibronic coupling mechanism to form a type of hybrid light−matter state we denote as Herzberg−Teller (HT) vibronic polaritons. We use simple models to define the basic characteristics of these hybrid light−matter excitations including their dispersive energies. Experimentally, we find evidence of HT polaritons in the light emission spectra from copper(II) tetraphenylporphyrin (CuTPP) molecules strongly coupled to both single and multimode Fabry−Perot resonator structures. For specific resonator designs, we find evidence of significant enhancement of light emission from a short-lived sing-doublet state of CuTPP, which couples to a higher energy singlet state via a non-Condon vibronic mechanism. The results of a two-state model support the conclusion that this enhancement and the temperature-dependent dispersion of the light emission peak energy stem from radiative relaxation into cavity photon states dressed by collective vibrations of the molecules participating in polariton formation. These results show how researchers can leverage the complex interplay of electronic and nuclear degrees of freedom in light absorbing molecules to form a vaster array of coherent light−matter states and potentially transform platforms in optoelectronic and photocatalytic technologies.

Control, Modulation, and Analytical Descriptions of Vibrational Strong Coupling

“…By far, the most common platform for evaluating strong coupling effects in both the visible and the infrared regimes is the Fabry–Pérot cavity, composed of two opposed parallel mirrors and supporting resonances in which the round-trip phase condition (the round-trip path length must be equal to an integer number of wavelengths in the medium) is satisfied (Figure ). In addition to a simple analytical description and amenability to industrial thin film processes, this platform is broadly experimentally accessible and, with small modifications, allows examination of more advanced intercavity and intermodal interactions …”

Cavity Polaritons Formed from Spatially Separated Quasi-degenerate Porphyrin Excitons: Structural Modulations of Bright and Dark State Energies and Compositions

“…The relatively narrow width of the Soret peak in the UV–vis absorption spectra of many porphyrin molecules makes them excellent candidates for cavity polariton formation, as demonstrated by several previous studies. − When coupled with appropriate measurements approaches, these narrow peak widths enable rigorous analysis of the ultrafast dynamics imprinted onto linear polariton spectra directly . Furthermore, the complex coupling between the B and Q states of some highly symmetric metalloporphyrins leads to the possible formation of polariton-like states whose energies lie far away from those resonator photons .…”

“…32 Furthermore, the complex coupling between the B and Q states of some highly symmetric metalloporphyrins leads to the possible formation of polariton-like states whose energies lie far away from those resonator photons. 34 These features of porphyrin cavity polaritons and the interesting phenomena they induce make them useful systems with which one can understand the properties of multipolaritons formed from quasi-degenerate molecular excitons.…”

Cavity Polaritons formed from Spatially Separated Quasi-degenerate Porphyrin Excitons: Energetics and Structures of Bright and Dark States

“…The relatively narrow width of the Soret peak in the UV-vis absorption spectra of many porphyrin molecules makes them excellent candidates for cavity polariton formation, as demonstrated by several previous studies. [28][29][30][31][32][33][34] When coupled with appropriate measurements approaches, these narrow peak widths enable rigorous analysis of the ultrafast dynamics imprinted onto linear polariton spectra directly. 32 Furthermore, the complex coupling between the B and Q states of some highly symmetric metalloporphyrins leads to the possible formation of polariton-like states whose energies lie far away from those resonator photons.…”