筛选非卤溶剂添加剂制备非富勒烯有机太阳能电池（英文）

Environmentally-friendly solvent processed fullerenefree organic solar cells enabled by screening halogenfree solvent additives

虽然近年来有机太阳能电池的能量转换效率已经超过13%,但是加工高效率有机太阳能电池的溶剂大多数是含卤溶剂,这些溶剂体系阻碍了有机太阳能电池的进一步发展.因此,探索使用绿色溶剂制备高效率电池具有重要意义.本文在非卤溶剂邻二甲苯作为主溶剂的前提下,通过筛选不同非卤溶剂作为添加剂制备高效有机太阳能电池,在PBDB-T:IT-M共混材料体系中,取得了11.6%的能量转换效率,该效率是使用非卤溶剂加工有机太阳能电池的最高效率之一.我们通过一系列形貌测试将共混薄膜形貌的相区尺寸,相区纯度以及结晶性等重要形貌参数与器件性能进行关联,这对非富勒烯有机太阳能电池的性能优化具有指导意义.本研究表明,通过细致筛选非卤溶剂添加剂调节共混薄膜的形貌,从而可以获得高性能的有机太阳能电池.

Though the power conversion efficiencies（PCEs） of organic solar cells（OSCs） have been boosted to 12%,the use of highly pollutive halogenated solvents as the processing solvent significantly hinders the mass production of OSCs. It is thus necessary to achieve high-efficiency OSCs by utilizing the halogen-free and environmentally-friendly solvents. Herein, we applied a halogen-free solvent system（oxylene/1-phenylnaphthalene, XY/PN） for fabricating fullerene-free OSCs, and a high PCE of 11.6% with a notable fill factor（FF） of 72% was achieved based on the PBDB-T：IT-M blend, which is among the top efficiencies of halogen-free solvent processed OSCs. In addition, the influence of different halogen-free solvent additives on the blend morphology and device performance metrics was studied by synchrotron-based tools and other complementary methods. Morphological results indicate the highly ordered molecular packing and highest average domain purity obtained in the blend films prepared by using XY/PN co-solvent are favorable for achieving increased FFs and thus higher PCEs in the devices.Moreover, a lower interaction parameter（χ） of the IT-M：PN pair provides a good explanation for the more favorable morphology and performance in devices with PN as the solvent additive, relative to those with diphenyl ether and Nmethylpyrrolidone. Our study demonstrates that carefully screening the non-halogenated solvent additive plays a vital role in realizing the efficient and environmentally-friendly solvent processed OSCs.