Overcoming energy disorder for cavity-enabled energy transfer in vibrational polaritons.

Energy disorder is ubiquitous in chemistry and physics. It can suppress polariton delocalization by disrupting molecular coherence–limiting polariton-modified properties. We investigated how energy disorders affect vibrational polariton dynamics by probing ultrafast dynamics in 2,6-di-tert-butylphenol in liquids (inhomogeneous) and solids (homogeneous) using two-dimensional infrared spectroscopy and molecular dynamics simulations. In liquids, energy disorder disrupted delocalization, preventing vibrational energy transfer. By contrast, with reduced inhomogeneity, vibrational strong coupling in solids restored delocalization and enabled energy transfer. We established a stringent delocalization criterion, requiring collective coupling strengths exceeding three times inhomogeneous linewidths to sustain polariton coherence. This finding highlights energy disorder's detrimental effects and outlines strategies to overcome localization—either by minimizing disorder through chemical control or by achieving sufficient couplings using advanced photonic structures. Editor's summary: Cavity-enabled energy transfer in vibrational polaritons is a promising route to manipulating chemical dynamics in condensed phases, yet the underlying mechanisms remain elusive. One important factor that has been largely overlooked is energy disorder, which is prevalent in chemistry and can significantly affect polariton delocalization and modify molecular dynamics. Yin et al. prepared 2,6-di-tert-butylphenol in both saturated solutions (inhomogeneous limit) and crystalline solids (homogeneous limit), which allowed them to probe the polaritonic effects of the same molecular polariton system in distinct disorder conditions (see the Perspective by Son). Using two-dimensional infrared spectroscopy and molecular dynamics simulation, the authors showed that energy disorder can suppress polariton delocalization and prevent the consequent cavity-enabled vibrational energy transfer. They also examined potential strategies to overcome disorder-induced localization effects. —Yury Suleymanov [ABSTRACT FROM AUTHOR]