Charge transfer dynamics in squaraine-naphthalene diimide copolymers.
Charge transfer dynamics in squaraine-naphthalene diimide copolymers.
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DOI：
10.1039/c3cp53455c
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发表时间：
2013-10
期刊：
影响因子：
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通讯作者：
S. Völker;A. Schmiedel;M. Holzapfel;C. Böhm;C. Lambert
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文献类型：
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作者：
S. Völker;A. Schmiedel;M. Holzapfel;C. Böhm;C. Lambert
本文合成了一种方英-萘二亚胺交替供体-受体低带隙聚合物（1.14-1.40 eV）及其单分子类似物。光谱电化学实验和瞬态吸收光谱分析表明，聚合物和单体均存在超快的电荷分离态居群。正方形部分的局部激发之后是中间态的填充，可能是电荷转移态，然后是完全的电荷分离，发生在大约2 ps内。电荷重组发生在5.2 ps内，可能是因为系统接近马库斯无障ET的最佳区域。瞬态吸收各向异性的测量表明，在电荷分离态的寿命内，既不发生电荷转移，也不发生能量转移，这表明该状态基本上局限于一个供体-受体对。
The synthesis of an alternating squaraine-naphthalene diimide donor-acceptor low band gap polymer (1.14-1.40 eV) as well as its monomolecular analogue is presented. Spectroelectrochemistry experiments and transient absorption spectroscopy in the fs-time regime reveal an ultrafast population of a charge separated state for both polymer and monomer. Local excitation of the squaraine moiety is followed by population of intermediate states, presumably charge transfer states, followed by full charge separation, which occurs within a ca. 2 ps. Charge recombination takes place within 5.2 ps, probably because the system is close to the Marcus optimal region for barrierless ET. For the polymer, measurements of the transient absorption anisotropy show that neither charge nor does energy transfer take place within the lifetime of the charge separated state, indicating that this state is essentially confined within one donor-acceptor pair.