材料科学
有机太阳能电池
接受者
光伏系统
富勒烯
能量转换效率
堆积
聚合物太阳能电池
共轭体系
光化学
化学工程
聚合物
光电子学
有机化学
化学
复合材料
生物
生态学
物理
工程类
凝聚态物理
作者
Mengxue Chen,Dan Liu,Wei Li,Robert S. Gurney,Donghui Li,Jinlong Cai,Emma L. K. Spooner,Rachel C. Kilbride,James D. McGettrick,Trystan Watson,Zhe Li,Richard Jones,David G. Lidzey,Tao Wang
标识
DOI:10.1021/acsami.9b07317
摘要
Fluorination of conjugated molecules has been established as an effective structural modification strategy to influence properties and has attracted extensive attention in organic solar cells (OSCs). Here, we have investigated optoelectronic and photovoltaic property changes of OSCs made of polymer donors with the non-fullerene acceptors (NFAs) ITIC and IEICO and their fluorinated counterparts IT-4F and IEICO-4F. Device studies show that fluorinated NFAs lead to reduced Voc but increased Jsc and fill-factor (FF), and therefore, the ultimate influence to efficiency depends on the compensation of Voc loss and gains of Jsc and FF. Fluorination lowers energy levels of NFAs, reduces their electronic band gaps, and red-shifts the absorption spectra. The impact of fluorination on the molecular order depends on the specific NFA, and the conversion of ITIC to IT-4F reduces the structural order, which can be reversed after blending with the donor PBDB-T. Contrastingly, IEICO-4F presents stronger π–π stacking after fluorination from IEICO, and this is further strengthened after blending with the donor PTB7-Th. The photovoltaic blends universally present a donor-rich surface region which can promote charge transport and collection toward the anode in inverted OSCs. The fluorination of NFAs, however, reduces the fraction of donors in this donor-rich region, consequently encouraging the intermixing of donor/acceptor for efficient charge generation.
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