An efficient strategy to supervise absorption, mobility, morphology of photovoltaic molecule by inserting a D-A unit. (July 2019)

• Record Type: Journal Article
• Authors: Gu, Ziqian; Guo, Jiali; Hao, Rulin; Lin, Zixuan; Qian, Yu; Ma, Chao; Fan, Yankai; Deng, Xiaoyuan; Zhang, Guangjun; Peng, Wenhong; Xia, Hao; Peng, Qiang; Zhu, Weiguo
• Is Part Of: Dyes and pigments. Volume 166(2019)
• Page Start: 515
• Page End: 522
• Publication Date: 2019-07
• Subjects: Oligomer -- Thiophene -- Difluorobenzothiazole -- Fullerene -- Organic solar cells; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2019.03.050
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: The absorption, mobility and morphology of molecules in the active layer have a crucial influence on photovoltaic properties of organic solar cells. In this work, we design an A1 -(D-A)2 -D-A1 type oligomer DRCN4FBT on the basis of an A1 -D-A-D-A1 type small molecule DRCN2FBT by inserting D-A unit. It is found that oligomer DRCN4FBT exhibits wider absorption spectrum and higher carrier mobility and better morphology than small molecule DRCN2FBT in active layer using fullerene PC71 BM as acceptor. The absorption and energy level, mobility, morphology of DRCN4FBT in active layer are well supervised by inserting D-A unit in DRCN2FBT. As a result, its power conversion efficiency and short current density are increased by about 20% for the DRCN4FBT/PC71 BM based organic solar cells in comparison with the DRCN2FBT/PC71 BM based devices. It indicates that simply increasing D-A unit in small molecules to construct oligomer is an efficient strategy to improve photovoltaic properties. Graphical abstract: An A1 -(D-A)2 -D-A1 type oligomer DRCN4FBT is designed and synthesized by simply inserting a D-A unit in an A1 -D-A-D-A1 type small molecule DRCN2FBT. Its absorption and energy level, mobility, morphology are well supervised by inserting D-A unit. As a result, both PCE and J sc are increased by about 20% for the DRCN4FBT/PC71 BM based devices. It indicates that simply increasing D-A units an efficient strategy to improve photovoltaic properties.Image 1 Highlights: An A1 -(D-A)2 -D-A1 type oligomer DRCN4FBT and its prototypical small molecule DRCN2FBT are synthesized. The strategy to supervise molecular absorption, mobility, crystallinity is provided. Their optical, electrochemical, morphological and photovoltaic properties are studied. DRCN4FBT shows better photovoltaic properties than DRCN2FBT in the PC71 BM based solar cells.