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Singlet Fission in Quaterrylenediimide Thin Films
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-01-22 , DOI: 10.1021/acs.jpcc.9b10397
Michelle Chen 1 , Natalia E. Powers-Riggs 1 , Adam F. Coleman 1 , Ryan M. Young 1 , Michael R. Wasielewski 1
Affiliation  

Singlet fission (SF) creates two triplet excitons following absorption of a photon by two electronically interacting chromophores. Quaterrylene-3,4:13,14-bis(dicarboximide) (QDI) is a strongly absorbing chromophore that readily fulfills the energetic requirements for SF, E(S1) > 2E(T1), and thus should undergo rapid and efficient SF. SF was studied in thin films of the QDI derivative N,N-bis(2,6-diisopropylphenyl)-QDI (ArQDI), which undergoes SF in <300 fs to form the correlated triplet pair state, 1(T1T1), which dissociates with a (7.3 ± 1.2 ns)−1 rate constant. The observed triplet yield for a thin film that has been solvent-vapor annealed with CH2Cl2 is 135 ± 20% instead of 200%, which is typically expected of chromophores that undergo ultrafast formation of the 1(T1T1) state. The lower SF yield in ArQDI results from the failure of the 1(T1T1) state to dissociate before returning to the ground state. In contrast to other molecules, like hexacene, which have low triplet energies, the SF rate in ArQDI is not limited by a multiphonon relaxation bottleneck, largely due to the fact that the S–T energy gap in the film is substantially smaller than that measured for monomeric ArQDI. The ability to maintain a favorable S–T energy gap in a film is a design consideration when chromophores are considered for use to enhance solar cell performance.

中文翻译:

季戊二烯二酰亚胺薄膜中的单重态裂变

单峰裂变(SF)在两个电子相互作用的生色团吸收光子后产生两个三重态激子。季戊三烯-3,4:13,14-双(二甲叉酰亚胺)(QDI)是一种强吸收性发色团,可以轻松满足SF,E(S 1)> 2 E(T 1)的能量要求,因此应快速进行。高效的SF。在QDI衍生物NN-双-(2,6-二异丙基苯基)-QDI(ArQDI)的薄膜中研究了SF,该薄膜在<300 fs内经历SF形成相关的三重态对态1(T 1 T 1)。 ,与(7.3±1.2 ns)-1分离速率常数。经CH 2 Cl 2溶剂蒸汽退火的薄膜的三重态产率为135±20%而不是200%,这通常是发色团经历1(T 1 T 1)超快形成所期望的。ArQDI中较低的SF产率是由于1(T 1 T 1)状态在返回基态之前无法解离的结果。相比于其它分子,如并六苯,其具有低的三线态能量,所述SF率ArQDI它不受多声子弛豫瓶颈的限制,这主要是由于薄膜中的S–T能隙远小于单体ArQDI所测得的。当考虑使用发色团来增强太阳能电池性能时,在设计中要考虑在薄膜中保持良好的TT能隙的能力。
更新日期:2020-01-23
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