Department of Biotechnology , Tokyo University of Agriculture and Technology , Nakacho, Koganei , Tokyo 184-8588 , Japan.
Ricoh Co., Ltd. , 16-1 Honda-machi , Numazu , Shizuoka 410-8505 , Japan.
ACS Appl Mater Interfaces. 2018 Apr 4;10(13):11083-11093. doi: 10.1021/acsami.8b01233. Epub 2018 Mar 20.
Solution-processed organic solar cells (OSCs) based on narrow-band gap small molecules hold great promise as next-generation energy-converting devices. In this paper, we focus on a family of A-π-D-π-A-type small molecules, namely, BDT- nT-ID ( n = 1-4) oligomers, consisting of benzo[1,2- b:4,5- b']dithiophene (BDT) as the central electron-donating (D) core, 1,3-indandione (ID) as the terminal electron-accepting (A) units, and two regioregular oligo(3-hexylthiophene)s ( nT) with different numbers of thiophene rings as the π-bridging units, and elucidate their structure-property-function relationships. The effects of the length of the π-bridging nT units on the optical absorption, thermal behavior, morphology, hole mobility, and OSC performance were systematically investigated. All oligomers exhibited broad and intense visible photoabsorption in the 400-700 nm range. The photovoltaic performances of bulk heterojunction OSCs based on BDT- nT-IDs as donors and a fullerene derivative as an acceptor were studied. Among these oligomers, BDT-2T-ID, incorporating bithiophene as the π-bridging units, showed better photovoltaic performance with a maximum power conversion efficiency as high as 6.9% under AM 1.5G illumination without using solvent additives or postdeposition treatments. These favorable properties originated from the well-developed interpenetrating network morphology of BDT-2T-ID, with larger domain sizes in the photoactive layer. Even though all oligomers have the same A-D-A main backbone, structural modulation of the π-bridging nT length was found to impact their self-organization and nanostructure formation in the solid state, as well as the corresponding OSC device performance.
基于窄带隙小分子的溶液处理有机太阳能电池（OSC）有望成为下一代能量转换器件。在本文中，我们专注于一类 A-π-D-π-A 型小分子，即 BDT- nT-ID（ n=1-4）齐聚物，由苯并[1,2-b:4,5-b']二噻吩（BDT）作为中心供电子（D）核，1,3-茚二酮（ID）作为末端受电子（A）单元，以及两个具有不同噻吩环数的两个区域规整的聚（3-己基噻吩）（ nT）作为π桥接单元组成，并阐明了它们的结构-性质-功能关系。π桥接 nT 单元长度对光学吸收、热行为、形态、空穴迁移率和 OSC 性能的影响进行了系统研究。所有齐聚物在 400-700nm 范围内均表现出宽而强的可见光吸收。以 BDT- nT-IDs 作为供体和富勒烯衍生物作为受体的体异质结 OSC 的光伏性能进行了研究。在这些齐聚物中，含有联噻吩作为π桥接单元的 BDT-2T-ID 表现出更好的光伏性能，在 AM1.5G 照明下，最高功率转换效率高达 6.9%，无需使用溶剂添加剂或后沉积处理。这些优良的性质源于 BDT-2T-ID 发达的互穿网络形态，在光活性层中具有更大的畴尺寸。尽管所有齐聚物都具有相同的 A-D-A 主链，但π桥接 nT 长度的结构调制被发现会影响它们在固态中的自组织和纳米结构形成，以及相应的 OSC 器件性能。
