Ye Long, Xiong Yuan, Chen Zheng, Zhang Qianqian, Fei Zhuping, Henry Reece, Heeney Martin, O'Connor Brendan T, You Wei, Ade Harald
Department of Physics, Organic and Carbon Electronics Lab (ORaCEL), North Carolina State University, Raleigh, NC, 27695, USA.
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
Adv Mater. 2019 Apr;31(17):e1808153. doi: 10.1002/adma.201808153. Epub 2019 Mar 15.
Casting of a donor:acceptor bulk-heterojunction structure from a single ink has been the predominant fabrication method of organic photovoltaics (OPVs). Despite the success of such bulk heterojunctions, the task ofcontrolling the microstructure in a single casting process has been arduous and alternative approaches are desired. To achieve OPVs with a desirable microstructure, a facile and eco-compatible sequential deposition approach is demonstrated for polymer/small-molecule pairs. Using a nominally amorphous polymer as the model material, the profound influence of casting solvent is shown on the molecular ordering of the film, and thus the device performance and mesoscale morphology of sequentially deposited OPVs can be tuned. Static and in situ X-ray scattering indicate that applying (R)-(+)-limonene is able to greatly promote the molecular order of weakly crystalline polymers and form the largest domain spacing exclusively, which correlates well with the best efficiency of 12.5% in sequentially deposited devices. The sequentially cast device generally outperforms its control device based on traditional single-ink bulk-heterojunction structure. More crucially, a simple polymer:solvent interaction parameter χ is positively correlated with domain spacing in these sequentially deposited devices. These findings shed light on innovative approaches to rationally create environmentally friendly and highly efficient electronics.
从单一油墨浇铸供体-受体本体异质结结构一直是有机光伏器件（OPV）的主要制造方法。尽管这种本体异质结取得了成功，但在单一浇铸过程中控制微观结构的任务一直很艰巨，因此需要其他方法。为了实现具有理想微观结构的有机光伏器件，本文展示了一种用于聚合物/小分子对的简便且生态兼容的顺序沉积方法。以一种名义上无定形的聚合物为模型材料，研究表明浇铸溶剂对薄膜的分子有序性有深远影响，从而可以调节顺序沉积的有机光伏器件的器件性能和中尺度形态。静态和原位X射线散射表明，使用（R）-（+）-柠檬烯能够极大地促进弱结晶聚合物的分子有序性，并仅形成最大的域间距，这与顺序沉积器件中12.5%的最佳效率密切相关。顺序浇铸的器件通常优于基于传统单油墨本体异质结结构的对照器件。更关键的是，在这些顺序沉积的器件中，一个简单的聚合物-溶剂相互作用参数χ与域间距呈正相关。这些发现为合理创建环境友好型高效电子产品的创新方法提供了启示。
