Tuning Triplet-Pair Separation versus Relaxation Using a Diamond Anvil Cell
Tuning Triplet-Pair Separation versus Relaxation Using a Diamond Anvil Cell
复制标题
DOI：
10.1016/j.xcrp.2019.100005
复制
发表时间：
2020-01-22
影响因子：
8.9
通讯作者：
Asbury, John B.
中科院分区：
文献类型：
--
作者：
Doucette, Grayson S.;Huang, Haw-Tyng;Asbury, John B.
三重态对分离与弛豫之间存在权衡，这可能会限制利用单重态裂变来提高太阳能电池效率超出肖克利-奎瑟极限的能力。在这里，我们表明，通过研究在金刚石砧室中压缩的功能化并五苯，可以在晶体环境中避免这种权衡。我们使用超快瞬态吸收光谱证明，存在一个“最佳点”，其中三重态对分离的速率可以加快近一个数量级，而不会引起快速激发态弛豫。 X 射线衍射和计算模型使我们能够量化分子间耦合的相应增加。我们的研究结果表明，增加的耦合增强了激发态弛豫，但结晶环境可以抑制并五苯衍生物中的这些弛豫过程。这些效应的组合导致了最佳点，并为提高无定形系统（例如聚合物）中的三重态对分离率提供了信息。
A tradeoff exists between triplet-pair separation versus relaxation that can limit the ability to utilize singlet fission for enhancing solar cell efficiency beyond the Shockley-Queisser limit. Here, we show that this tradeoff can be avoided in crystalline environments by studying a functionalized pentacene compressed in a diamond anvil cell. We demonstrate, using ultrafast transient absorption spectroscopy, that there is a "sweet spot" where the rate of triplet pair separation can be accelerated by nearly an order of magnitude without causing fast excited state relaxation. X-ray diffraction and computational modeling allow us to quantify the corresponding increase of intermolecular coupling. Our findings suggest that increased coupling enhances excited state relaxation but that crystalline environments can suppress these relaxation processes in pentacene derivatives The combination of these effects leads to the sweet spot and informs efforts to enhance triplet-pair separation rates in amorphous systems such as polymers.