Data to accompany "Conjugation Length Dependence of Intramolecular Singlet Fission in a Series of regioregular oligo 3-alkyl(thienylene-vinylene)s"

Activated intramolecular singlet fission is known to occur in the conjugated polymer polythienylene-vinylene (P3TV). Instead, efficient intersystem crossing has been observed in a short (3-alkyl(thienlylene-vinylene) dimer. Here we investigate a series of oligomers, covering the conjugation length gap between the dimer and polymer. We confirm that the polymer and longer oligomers undergo activated intramolecular singlet fission while the shorter oligomers with less than 3 units predominantly undergo efficient intersystem crossing. For the longer oligomers, the intermediate state of singlet fission is assigned to the 3Ag- covalent state of triplet pair character, as predicted by several computational studies. Our results point to potential pitfalls when assigning triplet production pathways solely with transient absorption spectroscopy.

激活型分子内单线态裂变（activated intramolecular singlet fission）已知发生于共轭聚合物聚噻吩乙烯（polythienylene-vinylene，P3TV）中。相反，在短链（3-烷基噻吩乙烯）二聚体中观察到了高效系间窜越（efficient intersystem crossing）。本文研究了一系列低聚物（oligomers），其共轭长度（conjugation length）填补了二聚体与聚合物之间的空白。我们证实，聚合物及较长低聚物发生激活型分子内单线态裂变，而单元数少于3的短链低聚物主要发生高效系间窜越。对于较长低聚物，单线态裂变的中间态（intermediate state of singlet fission）被归为具有三重态对特征（triplet pair character）的3Ag-共价态，正如多项计算研究所预测的那样。我们的结果表明，仅使用瞬态吸收光谱（transient absorption spectroscopy）来确定三重态产生途径（triplet production pathways）时存在潜在误区。