Department of Chemistry and Centre of Scientific Computing, University of Warwick, Coventry, United Kingdom.
Proc Natl Acad Sci U S A. 2012 Aug 21;109(34):13498-502. doi: 10.1073/pnas.1206172109. Epub 2012 Aug 6.
It is normally assumed that electrons and holes in organic solar cells are generated by the dissociation of excitons at the interface between donor and acceptor materials in strongly bound hole-electron pairs. We show in this contribution that excitons can dissociate tens of angstroms away from the interface and generate partially separated electrons and holes, which can more easily overcome their coulombic attraction and form free charges. We first establish under what conditions long-range exciton dissociation is likely (using a kinetic model and a microscopic model for the calculation of the long-range electron transfer rate). Then, defining a rather general model Hamiltonian for the donor material, we show that the phenomenon is extremely common in the majority of polymer:fullerene bulk heterojunction solar cells.
通常认为，有机太阳能电池中的电子和空穴是由施主和受主材料界面处激子的离解产生的，在强束缚的空穴-电子对中。在本研究中，我们表明激子可以在离界面数十埃的距离处离解，并产生部分分离的电子和空穴，这些电子和空穴更容易克服它们的库仑吸引力并形成自由电荷。我们首先使用动力学模型和长程电子转移速率的微观模型来确定长程激子离解可能发生的条件（使用动力学模型和微观模型来计算长程电子转移速率）。然后，我们为施主材料定义了一个相当通用的模型哈密顿量，结果表明，在大多数聚合物：富勒烯体异质结太阳能电池中，这种现象非常普遍。
