Photophysics and ultrafast exciton dynamics of 9,10-bis(triisopropylsilylethynyl)anthracene (TIPSAn) nanoaggregates and thin films are studied. The effect of molecular packing on singlet exciton relaxation is evaluated by comparing ultrafast dynamics in nanoparticles and vapor-deposited thin films. As compared to the strong emission of TIPSAn in solution, significant quenching of fluorescence in nanoaggregates and thin films suggests fast nonradiative relaxation of singlet excitons. In nanoaggregates, disordered molecular packing leads to long-lived excimer-state outcompeting singlet fission (SF)-mediated triplet formation. In microcrystalline thin films, exciton relaxation to the excimer state is inhibited due to ordered molecular packing and a significant fraction of singlet excitons undergo singlet fission, resulting in long-lived triplet excitons. However, the singlet fission yield in TIPSAn is much smaller than that of the structurally similar but strongly coupled anthracene derivative, namely 9,10-bis(phenylethynyl) anthracene (BPEA). The low yield of SF-mediated triplets in TIPSAn is attributed to weak intermolecular interactions due to larger intermolecular separation introduced by bulky triisopropylsilyl groups in crystalline thin films and additional competing exciton trapping to the excimer state in disordered nanoparticles.

中文翻译：

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9,10-双[(三异丙基甲硅烷基)乙炔基]蒽纳米聚集体和薄膜的超快动力学：分子堆积和样品形态对单线态裂变和准分子形成的影响

研究了 9,10-双（三异丙基甲硅烷基乙炔基）蒽 (TIPSAn) 纳米聚集体和薄膜的光物理学和超快激子动力学。通过比较纳米粒子和气相沉积薄膜的超快动力学来评估分子堆积对单线态激子弛豫的影响。与 TIPSAn 在溶液中的强发射相比，纳米聚集体和薄膜中荧光的显着猝灭表明单线态激子的快速非辐射弛豫。在纳米聚集体中，无序的分子堆积导致长寿命的准分子态胜过单线态裂变（SF）介导的三线态形成。在微晶薄膜中，由于有序分子堆积，激子弛豫到准分子态受到抑制，并且很大一部分单线态激子经历单线态裂变，从而产生长寿命的三线态激子。然而，TIPSAn 中的单线态裂变产率远小于结构相似但强耦合的蒽衍生物，即 9,10-双（苯乙炔基）蒽（BPEA）。TIPSAn 中 SF 介导的三重态的低产率归因于分子间相互作用较弱，这是由于结晶薄膜中庞大的三异丙基甲硅烷基基团引入的较大分子间分离以及无序纳米粒子中准分子态的额外竞争性激子捕获。