Hole-Induced Quenching of Triplet and Singlet Excitons in Conjugated Polymers

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• 作者：Andre J. Gesquiere ; So-Jung Park ; and Paul F. Barbara
• 刊名：Journal of the American Chemical Society
• 出版年：2005
• 出版时间：July 6, 2005
• 年：2005
• 卷：127
• 期：26
• 页码：9556 - 9560
• 全文大小：82K
• 年卷期：v.127,no.26(July 6, 2005)
• ISSN：1520-5126

文摘

Quantitative information on the mechanisms and rates of hole (radical cation)-induced quenchingof triplet and singlet excitons in the conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] has been acquired by a new technique, fluorescence-voltage time-resolved single moleculespectroscopy (FV-TR-SMS). FV-TR-SMS measures the fluorescence intensity of a single conjugated polymermolecule that is embedded in a capacitor-like device while simultaneously modulating the bias on the deviceand the irradiation intensity. The results demonstrate that triplet excitons are efficiently quenched by holesin conjugated polymers for hole densities >10¹⁶ charges/cm³, while singlet excitons are quenched with amuch lower efficiency. Detailed kinetic analysis shows that the greater efficiency for quenching of tripletsby holes (compared to that for singlets) is due to a >10⁶ times longer exciton lifetime for triplets. In fact,the results suggest that while singlet quenching is less efficient due to a much shorter singlet lifetime, therate constant for the quenching of singlets by holes actually exceeds that for triplets by several orders ofmagnitude.