Raba Adam, Cordan Anne-Sophie, Leroy Yann
Institut d'Electronique du Solide et des Systèmes (InESS), Université de Strasbourg/CNRS, ENSPS, Pole API, Bvd Sébastien Brant, Parc d'Innovation, BP 10413, F-67412 Illkirch, France.
J Nanosci Nanotechnol. 2013 Jul;13(7):5164-9. doi: 10.1166/jnn.2013.7501.
Recent developments in organic solar cells show interesting power conversion efficiencies. However, with the use of organic semiconductors and bulk heterojunction cells, many new concepts have to be introduced to understand their characteristics. Only few models investigate these new concepts, and most of them are one-dimensional only. In this work, we present a two-dimensional model based on solving the drift-diffusion equations. The model describes the generation of excitons in the donor phase of the active layer and their diffusion towards an interface between the two separate acceptor and donor domains. Then, when the exciton reaches the interface, it forms a charge transfer state which can split into free charges due to the internal potential. Finally, these free charges are transported toward the electrodes within their respective domains (electrons in acceptor domain, holes in donor domain) before being extracted. In this model, we can follow the distribution of each species and link it to the physical processes taken into account. Using the finite element method to solve the equations of the model, we simulate the effect of the bulk heterojunction morphology on photocurrent curves. We concentrate on the morphology parameters such as the mean acceptor/donor domain sizes and the roughness of,the interface between the donor and acceptor domains. Results are discussed in relation with experimental observations.
有机太阳能电池的最新进展显示出令人感兴趣的功率转换效率。然而，随着有机半导体和体异质结电池的使用，必须引入许多新概念来理解它们的特性。只有少数模型研究这些新概念，而且大多数模型仅为一维的。在这项工作中，我们提出了一个基于求解漂移扩散方程的二维模型。该模型描述了活性层供体相中激子的产生以及它们向两个独立的受体和供体域之间的界面的扩散。然后，当激子到达界面时，它形成一个电荷转移态，由于内部电势，该电荷转移态可以分裂成自由电荷。最后，这些自由电荷在被提取之前在各自的域内（受体域中的电子，供体域中的空穴）向电极传输。在这个模型中，我们可以跟踪每种物质的分布，并将其与所考虑的物理过程联系起来。使用有限元方法求解模型方程，我们模拟了体异质结形态对光电流曲线的影响。我们专注于形态参数，如平均受体/供体域尺寸以及供体和受体域之间界面的粗糙度。结合实验观察结果对结果进行了讨论。
