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.