†Department of Chemistry, Columbia University, New York, New York 10027, United States.
J Am Chem Soc. 2015 Jul 22;137(28):8965-72. doi: 10.1021/jacs.5b04986. Epub 2015 Jul 14.
Singlet fission (SF) has the potential to significantly enhance the photocurrent in single-junction solar cells and thus raise the power conversion efficiency from the Shockley-Queisser limit of 33% to 44%. Until now, quantitative SF yield at room temperature has been observed only in crystalline solids or aggregates of oligoacenes. Here, we employ transient absorption spectroscopy, ultrafast photoluminescence spectroscopy, and triplet photosensitization to demonstrate intramolecular singlet fission (iSF) with triplet yields approaching 200% per absorbed photon in a series of bipentacenes. Crucially, in dilute solution of these systems, SF does not depend on intermolecular interactions. Instead, SF is an intrinsic property of the molecules, with both the fission rate and resulting triplet lifetime determined by the degree of electronic coupling between covalently linked pentacene molecules. We found that the triplet pair lifetime can be as short as 0.5 ns but can be extended up to 270 ns.
单态裂变（SF）有可能显著提高单结太阳能电池的光电流，从而将功率转换效率从肖克利-奎塞尔极限的 33%提高到 44%。到目前为止，定量的室温单态裂变产率仅在晶体固体或齐聚物中观察到。在这里，我们采用瞬态吸收光谱、超快光致发光光谱和三重态光敏化来证明一系列双并五苯中的分子内单态裂变（iSF），其三重态产率接近每个吸收光子的 200%。至关重要的是，在这些体系的稀溶液中，SF 不依赖于分子间相互作用。相反，SF 是分子的固有特性，通过共价连接的并五苯分子之间的电子耦合程度来决定裂变速率和产生的三重态寿命。我们发现，三重态对寿命可以短至 0.5ns，但可以延长至 270ns。
