Department of Chemistry, Incheon National University, Incheon 22012, Republic of Korea.
Phys Chem Chem Phys. 2018 Dec 12;20(48):30083-30094. doi: 10.1039/c8cp06256k.
The highly unusual state, 1(TT), is a coupled, double triplet state that has recently garnered significant attention. This multiexcitonic state can be formed by a quantum transition from a single-photon bright state in a variety of organic semiconducting materials. 1(TT)'s transient nature and similarity to independent triplets, however, has led to significant difficulties in characterization and prediction of its properties. Recent progress describing 1(TT) from theory and experiment are breaking through these difficulties, and have greatly advanced our comprehension of this state. Starting from the early description of 1(TT) in polyenes, this perspective discusses formation mechanisms, spectroscopic signatures, and the scope of intertriplet interactions. When employing singlet fission to generate charge carriers in a solar cell, 1(TT) has a central role. Due to the variety of coupling strengths between triplet states in 1(TT) amongst different chromophores, two different strategies are discussed to enable efficient charge carrier extraction. Continued growth in our understanding of 1(TT) may lead to control over complex quantum states for intriguing applications beyond high-efficiency, organic solar cells.
1(TT) 态是一种高度非寻常的耦合双三重态，最近受到了广泛关注。这种多激子态可以通过各种有机半导体材料中从单光子亮态的量子跃迁形成。然而，1(TT) 的瞬态性质和与独立三重态的相似性，导致其性质的表征和预测存在重大困难。最近从理论和实验方面对 1(TT) 的研究进展正在克服这些困难，并极大地提高了我们对该态的理解。本综述从聚烯中的 1(TT) 的早期描述开始，讨论了其形成机制、光谱特征以及三重态间相互作用的范围。在利用单态裂变在太阳能电池中产生载流子时，1(TT) 起着核心作用。由于不同发色团之间 1(TT) 中三重态之间的耦合强度各不相同，因此讨论了两种不同的策略来实现有效的载流子提取。对 1(TT) 的理解不断加深，可能会导致对复杂量子态的控制，从而在高效有机太阳能电池之外的有趣应用中发挥作用。
