Manipulating Triplet Yield through Control of Symmetry-Breaking Charge Transfer,The Journal of Physical Chemistry Letters

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Manipulating Triplet Yield through Control of Symmetry-Breaking Charge Transfer
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2018-05-31 00:00:00 , DOI: 10.1021/acs.jpclett.8b01237
Saptaparna Das ₁ , William G. Thornbury ₂ , Andrew N. Bartynski ₂ , Mark E. Thompson ₁ , Stephen E. Bradforth ₁

Affiliation

The efficiency of an organic solar cell depends on the efficacy of exciton diffusion and dissociation processes, and this can be enhanced by reducing the exciton binding energy and increasing the exciton lifetime. Zinc chlorodipyrrin (ZCl) complexes exhibit reduced exciton binding energy due to ultrafast generation of intramolecular charge transfer (ICT) states via symmetry-breaking charge transfer in polar media. This Letter explores the fate of the ICT states using nanosecond transient absorption. In cyclohexane, ZCl undergoes intersystem crossing to produce triplets with ∼8 ns time constant (∼30% yield), and no ICT states are generated. However, in more polar solvents, triplets are generated within 1 ns via ICT state recombination with ∼3 times higher yield than produced via ISC. This high triplet yield in toluene (89%) and acetonitrile (76%) via ICT state recombination is a beneficial pathway to spin-protect the excited-state decay for additional charge generation from triplet excited states.

中文翻译：

通过控制突破对称电荷转移来操纵三重态产率

有机太阳能电池的效率取决于激子扩散和离解过程的效率，可以通过降低激子结合能和延长激子寿命来提高效率。氯双吡啶锌（ZCl）络合物由于在极性介质中通过对称破坏电荷转移而超快生成分子内电荷转移（ICT）状态，因此激子结合能降低。这封信使用纳秒瞬态吸收来探讨ICT国家的命运。在环己烷中，ZCl进行系统间交换以产生约8 ns时间常数（约30％收率）的三重态，并且不会产生ICT状态。但是，在极性更大的溶剂中，通过ICT状态重组，在1 ns内会产生三重态，其收率是通过ISC产生的三倍。

更新日期：2018-05-31

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