Under-strain Synergistic Oscillatory Twisting Manipulates the Bifunction in Rubrene Crystal

Photophysical properties of condensed systems generally originate from collective contributions of all components in their stochastically fluctuated structures and are strongly influenced under strain of chromophores. To precisely identify how the stochastically fluctuated monomers synergistically manipulate the properties, we propose a statistic strategy over sufficient ab initio molecular dynamics (AIMD) samplings and for the first time uncover that synergistic oscillatory twisting (SOT) of neighboring under-strain monomers manipulates the bifunction of rubrene crystal. The under-strain trunk SOT can regulate both singlet fission (SF) and triplet-triplet annihilation (TTA), enabling their coexistence and dominance switching by dynamically modulating the matching of excitation energies. A general rule is that small amplitude of SOT maintains the crystal TTA, while the large one boosts SF and the SF function occurs only when two neighboring monomers simultaneously have the twisting angles larger than the critical one. Temperature can govern the twisting amplitudes, thus manipulating the bifunction. These findings rationalize the experimentally observed temperature-modulated bifunction of rubrene crystal from statistical insights and proposes a combined strain-fluctuation strategy for engineering the bifunctionality of materials.