Synthesis and Exciton Dynamics of Triplet Sensitized Conjugated Polymers

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• 作者：Rolf Andernach ; Hendrik Utzat ; Stoichko D. Dimitrov ; Iain McCulloch ; Martin Heeney ; James R. Durrant ; Hugo Bronstein
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：August 19, 2015
• 年：2015
• 卷：137
• 期：32
• 页码：10383-10390
• 全文大小：493K
• ISSN：1520-5126

文摘

We report the synthesis of a novel polythiophene-based host鈥揼uest copolymer incorporating a Pt鈥損orphyrin complex (TTP鈥揚t) into the backbone for efficient singlet to triplet polymer exciton sensitization. We elucidated the exciton dynamics in thin films of the material by means of Transient Absorption Spectrosopcy (TAS) on multiple time scales and investigated the mechanism of triplet exciton formation. During sensitization, singlet exciton diffusion is followed by exciton transfer from the polymer backbone to the complex where it undergoes intersystem crossing to the triplet state of the complex. We directly monitored the triplet exciton back transfer from the Pt鈥損orphyrin to the polymer and found that 60% of the complex triplet excitons were transferred with a time constant of 1087 ps. We propose an equilibrium between polymer and porphyrin triplet states as a result of the low triplet diffusion length in the polymer backbone and hence an increased local triplet population resulting in increased triplet鈥搕riplet annihilation. This novel system has significant implications for the design of novel materials for triplet sensitized solar cells and upconversion layers.