Triplet Separation Drives Singlet Fission after Femtosecond Correlated Triplet Pair Production in Rubrene
Triplet Separation Drives Singlet Fission after Femtosecond Correlated Triplet Pair Production in Rubrene
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DOI：
10.1021/jacs.7b02621
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发表时间：
2017-08-30
影响因子：
15
通讯作者：
Turner, Daniel B.
中科院分区：
文献类型：
--
作者：
Breen, Ilana;Tempelaar, Roel;Turner, Daniel B.
单线态裂变是一个多步骤的分子过程，其中一个光子产生两个三线态激子，具有巨大的技术前景。在这里，通过将瞬态透射率和二维电子光谱与5 fs激光脉冲相结合，我们解决了自旋退相开始前的全套裂变步骤。除了它作为一个可行的单线态裂变材料的作用，单晶红荧烯的选择，因为它的能量和过渡偶极对齐独特地允许明确的识别的各种裂变步骤，通过其贡献不同的光谱特征。测量结果表明，相邻的相关三重态对达到其最大人口在20 fs。随后的增长的三重态信号的皮秒时间尺度是由于空间分离的三重态，通过弱耦合，但近共振状态的非线性进行。因此，我们提供的证据，在结晶红荧烯的单线态裂变的步骤，到目前为止，还没有令人信服地观察到。
Singlet fission, a multistep molecular process in which one photon generates two triplet excitons, holds great technological promise. Here, by applying a combination of transient transmittance and two-dimensional electronic spectroscopy with 5 fs laser pulses, we resolve the full set of fission steps before the onset of spin dephasing. In addition to its role as a viable singlet fission material, single-crystalline rubrene is selected because its energetics and transition dipole alignment uniquely allow for the unambiguous identification of the various fission steps through their contributions to distinct spectroscopic features. The measurements reveal that the neighboring correlated triplet pair achieves its maximum population within 20 fs. Subsequent growth of the triplet signal on picosecond time scales is attributable to spatial separation of the triplets, proceeding nonadiabatically through weakly coupled but near-resonant states. As such, we provide evidence in crystalline rubrene for a singlet fission step that, until now, has not been convincingly observed.