Abstract: In the conventional framework of organic optoelectronics, strong electron–phonon coupling between excited-state electrons and molecular vibrations or lattice phonons typically leads to ultrafast nonradiative energy dissipation, thereby limiting further improvements in optical electronics efficiency and device performance. To address this challenge, extensive efforts over the past decade have focused on suppressing nonradiative transitions by weakening nonadiabatic electron–phonon coupling channels through molecular rigidification, conformational restriction, and structural regulation at molecular, material and device levels. Recent studies, however, have demonstrated that phonon dynamics in organic aggregate systems with highly ordered structures do not necessarily proceed on ultrafast timescales. Using experimental approaches such as photoexcitation-modulated Raman spectroscopy, anomalously slow phonon relaxation behaviors extending from milliseconds to seconds have been observed in specifically ordered aggregates. Experimental investigations reveal that, when phonon relaxation is significantly prolonged, the rate of nonradiative energy transfer from excited-state electrons to the lattice vibrations becomes constrained by the slow phonon dynamics. As a result, excited-state lifetimes are dynamically prolonged and the evolution pathways of excited states are effectively modulated. In parallel, in ordered donor–acceptor aggregate systems, the cooperative interplay between intermolecular charge-transfer excited states and polarized structures can induce an unconventional spin–orbit coupling that is distinct from the traditional heavy-atom mechanism. Rather than originating from atomic relativistic effects, this unconventional spin–orbit coupling manifests as polarization-stabilized spin-mixing and spin-conversion channels acting on excited-state dynamics, which can be experimentally determined by magnetic field effects of photoluminescence. This review systematically summarizes the conventional physical picture of electron–phonon-coupling-induced nonradiative decay in aggregated organic molecular systems and outlines the major strategies at molecular, material, and device levels towards suppressing nonradiative losses to improve optoelectronic efficiencies. It further highlights recent representative advancements in anomalously slow phonon dynamics and their role in regulating excited-state dynamics, as well as establishing unconventional spin–orbit coupling phenomena induced by charge-transfer states and polarized structures. On this basis, we introduce the concept of “phonon-gain optoelectronic effects,” in which phonons are regarded not merely as energy dissipation channels but as active regulators of excited-state dynamics. This framework emphasizes the abnormal slow phonon dynamics, unconventional SOC, and transformative spin electronics processes in organic optoelectronic systems.

Key words: Aggregated luminescence, Electron–phonon coupling; Ultra-slow Phonon Dynamics, Phonon-gain optoelectronic effect