Fazzi Daniele, Barbatti Mario, Thiel Walter
Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany.
Aix Marseille Univ, CNRS, ICR , 13013 Marseille, France.
J Phys Chem Lett. 2017 Oct 5;8(19):4727-4734. doi: 10.1021/acs.jpclett.7b02144. Epub 2017 Sep 18.
The evolution of the excited-state manifold in organic D/A aggregates (e.g., the prototypical P3HT/PCBM) is investigated through a bottom-up approach via first-principles calculations. We show how the excited-state energies, the charge transfer (CT) states, and the electron-hole density distributions are strongly influenced by the size, the orientation, and the position (i.e., on-top versus on-edge phases) of P3HT/PCBM domains. We discuss how the structural order influences the excited-state electronic structure, providing an atomistic interpretation of the photophysics of organic blends. We show how the simultaneous presence of on-top and on-edge phases does not alter the optical absorption spectrum of the blend but does affect the photophysics. Photovoltaic processes such as (i) the simultaneous charge generation obtained from hot and cold excitations, (ii) the instantaneous and delayed charge separation, and (iii) the pump-push-probe charge generation can be interpreted based on our study.
通过自下而上的方法，利用第一性原理计算研究了有机供体/受体聚集体（例如典型的P3HT/PCBM）中激发态流形的演化。我们展示了激发态能量、电荷转移（CT）态以及电子-空穴密度分布如何受到P3HT/PCBM域的大小、取向和位置（即顶对顶与边对边相）的强烈影响。我们讨论了结构有序性如何影响激发态电子结构，为有机共混物的光物理提供了原子层面的解释。我们展示了顶对顶相和边对边相的同时存在如何不改变共混物的光吸收光谱，但却会影响光物理过程。诸如（i）从热激发和冷激发获得的同时电荷产生、（ii）瞬时和延迟电荷分离以及（iii）泵浦-推挽-探测电荷产生等光伏过程可以基于我们的研究得到解释。
