Spiroconjugation-enhanced intramolecular charge-transfer state formation in a polyspirobifluorene homopolymer
Spiroconjugation-enhanced intramolecular charge-transfer state formation in a polyspirobifluorene homopolymer
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DOI：
10.1021/jp0755138
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发表时间：
2007-12-20
影响因子：
3.7
通讯作者：
Monkman, A. P.
中科院分区：
文献类型：
--
作者：
King, S. M.;Hintschich, S. I.;Monkman, A. P.
在这项工作中，我们展示了聚螺联荧烯在固态中的复杂激发态行为，由于螺旋共轭侧基的相互作用，容易形成比单重态激子能量更低的电荷转移(CT)激发态。利用泵浦探测和场辅助泵浦探测光谱将聚合物与标准的聚荧烯材料进行了比较。研究发现，单重态激子和CT态之间的小能垒允许室温下发射单重态的布居，与低温下的表观单指数寿命相比，在单重态寿命中产生了较长的尾部。提出了在器件中，CT态在电荷复合时填充，然后由CT态的电子转移激发单重态。
In this work we demonstrate the complex excited-state behavior of polyspirobifluorene in the solid state, which, due to the interaction of the spiroconjugated side group, readily forms a charge-transfer (CT) excited state of lower energy than the singlet exciton. The polymer is compared to standard polyfluorene materials using pump-probe and field-assisted pump-probe spectroscopy. It has been found that the small energy barrier between the singlet exciton and the CT state allows for population of the emissive singlet state at room temperature giving rise to a long tail in the singlet lifetime compared to an apparent single-exponential lifetime at low temperature. It is proposed that in devices the CT state is populated on charge recombination before the singlet states are excited by electron transfer from the CT state.