New dithienyl-diketopyrrolopyrrole-based conjugated molecules entailing electron withdrawing moieties for organic ambipolar semiconductors and photovoltaic materials
作者:Chenmin Yu、Zitong Liu、Yang Yang、Jingjing Yao、Zhengxu Cai、Hewei Luo、Guanxin Zhang、Deqing Zhang
DOI:10.1039/c4tc01872a
日期:——
In this paper we report two DPP-based conjugated molecules DPPBT and DPPTT in which the respective electron withdrawing moieties 2,1,3-benzothiadiazole and thiazolo[5,4-d]thiazole are flanked by two DPP moieties. For comparison, DPPBZ containing 1,4-diethynylbenzene and two DPP moieties were synthesized. HOMO/LUMO energies of DPPBT, DPPTT and DPPBZ were estimated on the basis of cyclic voltammetric data. Owing to the fact that LUMO energies of DPPBT and DPPTT were lowered to ca. −3.5 eV, thin films of both DPPBT and DPPTT exhibit ambipolar semiconducting properties under N2 atmosphere with hole and electron mobilities up to 0.25 cm2 V−1 s−1 and 0.09 cm2 V−1 s−1, respectively. In comparison, thin film of DPPBZ just shows p-type semiconducting property. Notably, ambipolar semiconductors with relatively high carrier mobility are rarely reported for DPP-containing small conjugated molecules. Alternatively, both DPPBT and DPPTT can function as electron donors for photovoltaic materials. Thin films of DPPTT:PC71BM and DPPBT:PC71BM at a weight ratio of 1 : 1 exhibit PCEs of 4.18% and 2.44%, respectively, with VOC higher than 0.95 V.
在本文中,我们报告了两种基于 DPP 的共轭分子 DPPBT 和 DPPTT,其中 2,1,3-苯并噻二唑和噻唑并[5,4-d]噻唑各自的取电子分子两侧有两个 DPP 分子。为了进行比较,还合成了含有 1,4-二乙炔苯和两个 DPP 分子的 DPPBZ。根据循环伏安数据估算了 DPPBT、DPPTT 和 DPPBZ 的 HOMO/LUMO 能量。由于 DPPBT 和 DPPTT 的 LUMO 能量降低到了约 -3.5 eV,因此薄膜的化学性质变得更好。由于 DPPBT 和 DPPTT 的 LUMO 能被降低到约 -3.5 eV,因此在 N2 气氛下,DPPBT 和 DPPTT 的薄膜都表现出两极半导体特性,空穴和电子迁移率分别高达 0.25 cm2 V-1 s-1 和 0.09 cm2 V-1 s-1。相比之下,DPPBZ 薄膜只显示出 p 型半导体特性。值得注意的是,含有 DPP 的小共轭分子很少被报道为具有相对较高载流子迁移率的双极性半导体。另外,DPPBT 和 DPPTT 都可以作为光伏材料的电子供体。DPPTT:PC71BM 和 DPPBT:PC71BM 的重量比为 1 :1 的薄膜的 PCE 值分别为 4.18% 和 2.44%,VOC 值高于 0.95 V。