Ultrafast Excited-State Dynamics of Diketopyrrolopyrrole (DPP)-Based Materials: Static versus Diffusion-Controlled Electron Transfer Process,The Journal of Physical Chemistry C

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Ultrafast Excited-State Dynamics of Diketopyrrolopyrrole (DPP)-Based Materials: Static versus Diffusion-Controlled Electron Transfer Process
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2015-07-07 00:00:00 , DOI: 10.1021/acs.jpcc.5b03905
Qana A. Alsulami ₁ , Shawkat M. Aly ₁ , Subhadip Goswami ₂ , Erkki Alarousu ₁ , Anwar Usman ₁ , Kirk S. Schanze ₂ , Omar F. Mohammed ₁

Affiliation

Singlet-to-triplet intersystem crossing (ISC) and photoinduced electron transfer (PET) of platinum(II)-containing diketopyrrolopyrrole (DPP) oligomers in the presence and absence of tetracyanoethylene (TCNE), a strong electron acceptor, were investigated using femtosecond and nanosecond transient absorption spectroscopy with broadband capabilities. The effect of incorporating platinum(II) on the photophysical properties of DPP molecule was evaluated by comparing the excited-state dynamics of DPP with and without Pt metal centers. Steady-state measurements reveal that platinum(II) incorporation greatly facilitates interactions between DPP-Pt(acac) and TCNE, resulting in the formation of charge transfer (CT) complexes. In the absence of TCNE, the transient absorption spectra revealed ultrafast ISC of DPP-Pt(acac) followed by a long-lived triplet state; however, in the presence of TCNE, PET from the excited DPP-Pt(acac) and from DPP to TCNE formed radical ion pairs. We measured an ultrafast PET from DPP-Pt(acac) to TCNE (i.e., a picosecond regime) that was much faster than that from DPP to TCNE (i.e., nanosecond time scale), which is a diffusion-controlled process. Our results provide clear evidence that the PET rate is eventually controlled by the platinum(II) incorporation.

中文翻译：

基于二酮吡咯并吡咯（DPP）的材料的超快激发态动力学：静态与扩散控制的电子转移过程

使用飞秒和四氟甲基苯甲酸酯，研究了在存在和不存在强电子受体四氰基乙烯（TCNE）的情况下，含铂（II）的二酮吡咯并吡咯（DPP）低聚物的单重态到三重态的系统间穿越（ISC）和光诱导电子转移（PET）。具有宽带功能的纳秒瞬态吸收光谱。通过比较具有和不具有Pt金属中心的DPP的激发态动力学，评估了掺入铂（II）对DPP分子的光物理性质的影响。稳态测量表明，铂（II）的结合极大地促进了DPP-Pt（acac）与TCNE之间的相互作用，从而导致电荷转移（CT）络合物的形成。在没有TCNE的情况下，瞬态吸收光谱揭示了DPP-Pt（acac）的超快ISC，随后是长寿命的三重态。然而，在TCNE的存在下，PET从激发的DPP-Pt（acac）以及从DPP到TCNE形成了自由基离子对。我们测量了从DPP-Pt（acac）到TCNE（即皮秒状态）的超快PET，它比从DPP到TCNE（即纳秒级）的速度快得多，这是一个扩散受控的过程。我们的结果提供了明确的证据，表明PET的最终转化率最终受铂（II）结合的控制。这是一个扩散控制的过程。我们的结果提供了明确的证据，表明PET的最终转化率最终受铂（II）结合的控制。这是一个扩散控制的过程。我们的结果提供了明确的证据，表明PET的最终转化率最终受铂（II）结合的控制。

更新日期：2015-07-07

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