Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Wegelerstrasse 12, D-53115 Bonn, Germany.
J Phys Chem B. 2011 Nov 24;115(46):13526-33. doi: 10.1021/jp208334y. Epub 2011 Nov 2.
Photoinduced charge separation in blends of organic materials of different electronic affinity and in organic donor-acceptor hybrids is a process of increasing importance for biological and artificial energy conversion and photovoltaics. Organic polymer solar cells are composed of an electron donor and an electron acceptor between which an electron transfer occurs after excitation by sunlight. Charge separation results in the formation of donor cation radicals and acceptor anion radicals. Here, we present our studies on a donor-acceptor hybrid molecule composed of a phenylene-bithiophene macrocycle used as a donor and a perylene bisimide acceptor. Using continuous wave EPR and modern pulsed EPR methodology in combination with light excitation, intermolecular as well as intramolecular charge separation has been observed. Light-induced charge separation observed upon selective excitation of either one of the chromophores indicates that both LUMO-based and HOMO-based electron transfer from donor to acceptor takes place. These experimental findings are corroborated by DFT calculations in which the HOMO of the donor-acceptor hybrid molecule is found at the phenylene-bithiophene macrocycle and the LUMO at the perylene bisimide.
在具有不同电子亲和能的有机材料混合物以及有机给体-受体杂化体中，光诱导电荷分离对于生物和人工能量转换和光伏越来越重要。有机聚合物太阳能电池由电子给体和电子受体组成，在阳光激发后，电子在它们之间发生转移。电荷分离导致供体阳离子自由基和受体阴离子自由基的形成。在这里，我们介绍了我们对由苯并噻吩大环作为给体和苝二酰亚胺受体组成的给体-受体杂化分子的研究。使用连续波 EPR 和现代脉冲 EPR 方法结合光激发，观察到了分子间和分子内电荷分离。选择性激发其中一个生色团时观察到的光诱导电荷分离表明，从供体到受体的基于 LUMO 和 HOMO 的电子转移都发生了。这些实验结果得到了 DFT 计算的证实，其中发现供体-受体杂化分子的 HOMO 在苯并噻吩大环上，而 LUMO 在苝二酰亚胺上。
