活性层形貌可控的三元有机太阳能电池

Morphology controllable organic solar cells

近年来,由多组分材料共混构建的三元体系有机太阳能电池受到越来越多的关注.由于三元器件主要是通过各组分共混,采用溶液加工的方法制备器件的活性层,因而如何通过第三组分材料的引入来调控各组分分子间的相互作用力、分相方式、聚集尺度、以及分子以何种方式排列等是人们关注的焦点.这些因素对三元有机太阳能的器件的开路电压、短路电流和填充因子等参数和太阳能电池的最终效率具有较大的影响.本文主要总结了基于PC71BM受体的三元体系有机太阳能电池,包括:通过第三组分材料的引入来实现三元器件中"类合金模型"的形成;同一三元体系中,在不同共混比例下"类合金模型与平行模型"的共存现象;同一三元体系相同共混比例下,"类合金模型"与"级联(Cascade)模型"之间的转化,以及哪种工作机制更有利于激子的分离与电荷的收集.本文为深入理解三元体系有机太阳能电池活性层形貌结构与器件性能之间的关系,进一步提升器件性能提供了参考.

In recent years,ternary organic solar cells constructed from multi-component materials have attracting more and more attention.Since ternary organic solar cells are mainly prepared by blending multi-components and preparing the active layer of the device by solution processing,how to control the interaction force,phase separation and the aggregation scale of each component,as well as the way in which molecules are arranged by the introduction of the third component material are the studying focus.These factors have a large impact on the parameters such as the open circuit voltage,short circuit current,fill factor and the final power conversion efficiency of the ternary organic solar cells.This paper mainly summarizes the ternary organic solar cells based on PC71 BM as acceptor material.Firstly,by introduction of the third component material,"alloy model" charge transport in the ternary organic solar cell was introduced.The arrangement of the molecules in the active layer was investigated by grazing incident wide-angle X-ray scattering and resonance soft X-ray scattering.With the increase of small molecule donor incorporation ratio,the π-π stacking distance between molecules decreases gradually,which indicates that the introduced organic small molecule donor material is inserted into the polymer layer.It is more conducive to the transfer of charges between molecules.Afterward,the "Cascade model" and "parallel model" in the ternary system organic solar cell are summarized.Under different donors’ blending ratios,the coexistence of "alloy model" and "parallel model" in the same ternary system was realized.The two working models are both beneficial to the improvement of the performance of the ternary system.Especially,the conversion between "alloy model" and "cascade model" under the same blend ratio of the same ternary system was also realized.By studying the difference between the "alloy model" and the "cascade model" under the same blend ratio,we conclude that the "cascade model" is indeed more conducive to the separation of excitons and charge collection.Its power conversion efficiency is also more prominent.Lastly,topics of the development directions and prospect efficiency improve methods of the ternary organic solar cells are outlined.In summary,this review provides an in-depth understanding of the effective regulation of the phase separation scale and molecular arrangement of different components in the active layer of ternary organic solar cells and its relationship with device performance.This provides a reference for us to further improve device performance.