Competition between polaron pair formation and singlet fission observed in amorphous rubrene films
Competition between polaron pair formation and singlet fission observed in amorphous rubrene films
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DOI：
10.1103/physrevb.87.224202
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发表时间：
2013-06-04
影响因子：
3.7
通讯作者：
Monkman, Andrew P.
中科院分区：
文献类型：
--
作者：
Jankus, Vygintas;Snedden, Edward W.;Monkman, Andrew P.
在本文中，我们研究了非晶红荧烯真空升华薄膜的激发态动力学。我们报告了非晶红荧烯薄膜中单线态裂变的直接观察。我们确定裂变速率>2.5 x 10(12) s(-1)。同时，我们观察到强烈的极化子对吸收，并提出极化子对的形成可能与单线态裂变竞争。我们的实验的另一个可能的结论是，单线态裂变中的两个三线态可能通过极化子对产生。在任何一种情况下，极化子对在非晶红荧烯薄膜的单线态裂变中都起着重要作用。我们还观察到，由单线态裂变产生的三重态融合以再生单线态，延迟荧光（DF）随初始激光能量线性缩放（即，一个单线态产生两个三线态，两个三线态返回一个单线态）。这是S-1(n) -> 2T(1) 的有力证据。我们没有观察到 DF 衰变曲线形状的显着温度依赖性，这表明非晶红荧烯薄膜中的三重态迁移不受跳跃限制，并且三重态在迁移之前经历融合。
In this paper, we investigate excited state dynamics in amorphous rubrene vacuum sublimed films. We report the direct observation of singlet fission in amorphous rubrene films. We have determined the fission rate to be >2.5 x 10(12) s(-1). Simultaneously, we observe strong polaron pair absorption and propose that polaron pair formation could be competing with singlet fission. Another possible conclusion from our experiments could be that two triplets from singlet fission might arise via polaron pairs. In either case, polaron pairs play an important role in singlet fission in an amorphous rubrene film. We also observe that triplets created by singlet fission fuse to regenerate a singlet, giving delayed fluorescence (DF) scaling linearly with initial laser energy (i.e., one singlet gives two triplets and two triplets give back one singlet). This is a strong evidence of S-1(n) -> 2T(1). We did not observe substantial temperature dependence of DF decay curve shape, indicating that triplet migration in amorphous rubrene films is not hopping limited and that triplets undergo fusion before their migration.