Zhou Ping, Nazari Haghighi Pashaki Maryam, Frey Hans-Martin, Hauser Andreas, Decurtins Silvio, Cannizzo Andrea, Feurer Thomas, Häner Robert, Aschauer Ulrich, Liu Shi-Xia
Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
Institute of Applied Physics, University of Bern Sidlerstrasse 5 CH-3012 Bern Switzerland
Chem Sci. 2023 Oct 25;14(44):12715-12722. doi: 10.1039/d3sc03184e. eCollection 2023 Nov 15.
In fused donor-acceptor (D-A) ensembles, rapid charge recombination often occurs because the D and A units are spatially close and strongly coupled. To the best of our knowledge, a long-lived charge separated (CS) state is still elusive in such systems. The results presented here show that symmetric annulation of two tetrathiafulvalene (TTF) donors to a central tetraazapyrene (TAP) acceptor two quinoxaline units leads to a CS state lifetime of a few ns. A detailed study of the electronic interactions between TTF and TAP units in the ground and excited states was performed and compared with the asymmetric counterpart by cyclic voltammetry, optical absorption and ultrafast transient absorption spectroscopy. The results demonstrate that the photoinduced asymmetric charge trapping between two TTFs significantly stabilizes the CS state, which is also verified theoretically.
在融合的供体-受体（D-A）体系中，由于供体（D）和受体（A）单元在空间上接近且耦合强烈，常常会发生快速的电荷复合。据我们所知，在这样的体系中，长寿命的电荷分离（CS）态仍然难以实现。此处展示的结果表明，将两个四硫富瓦烯（TTF）供体对称地环合到中心四氮杂芘（TAP）受体（两个喹喔啉单元）上，会导致CS态寿命达到几纳秒。通过循环伏安法、光吸收和超快瞬态吸收光谱，对基态和激发态下TTF与TAP单元之间的电子相互作用进行了详细研究，并与不对称类似物进行了比较。结果表明，两个TTF之间光诱导的不对称电荷俘获显著稳定了CS态，这一点也得到了理论验证。
