The enhanced performance of fluorinated quinoxaline-containing polymers by replacing carbon with silicon bridging atoms on the dithiophene donor skeleton
The enhanced performance of fluorinated quinoxaline-containing polymers by replacing carbon with silicon bridging atoms on the dithiophene donor skeleton
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DOI：
10.1039/c4py01622j
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发表时间：
2015-03
影响因子：
4.6
通讯作者：
Xiaopeng Xu;Kai Li;Zuojia Li;Ying Li;Zhenguo Wang;Q. Peng
中科院分区：
文献类型：
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作者：
Xiaopeng Xu;Kai Li;Zuojia Li;Ying Li;Zhenguo Wang;Q. Peng
氟化喹啉单元是构建低带隙光伏聚合物的有吸引力的受体块。在本论文中，通过环戊二噻吩（CPDT）或二噻唑（DTS）给体嵌段在聚合物骨架上的结合，成功合成了两种新型氟化喹啉基共聚物PCPDTBFQ和PDTSBFQ。桥接原子效应对材料的吸收性能、能级、载流子迁移率和光电性能都有很大的影响。具有Si桥接原子的PDTSBFQ在紫外-可见吸收中表现出轻微的蓝移，并且带隙略大于PCPDTBFQ。然而，即使在溶液状态下，PDTSBFQ也表现出更强的聚集性。与碳原子相比，二氧化硅原子提供的PDTSBFQ具有较低的HOMO能级，表明聚合物太阳能电池（PSCs）具有较高的Voc。从XRD研究结果来看，PDTSBFQ比PCPDTBFQ具有更好的结晶度和分子有序性。基于PDTSBFQ的纯空穴器件的空穴迁移率为1.5 × 10−5 cm2 V−1 s−1，高于PCPDTBFQ的4.1 × 10−6 cm2 V−1 s−1。制备了传统的PSCs，研究了桥接原子效应对这两种共聚物光伏性能的影响。通过不同的Ca和PFN界面层（IFLs）来优化制备的psc的性能。使用Ca/Al顶电极时，PCPDTBFQ和PDTSBFQ器件的pce分别为2.16%和4.43%。PDTSBFQ器件的良好性能可归因于通过选择硅桥接原子提高了其Voc、Jsc和FF值。用PFN/Al阴极代替Ca/Al后，PCPDTBFQ和PDTSBFQ器件的性能都得到了很大的提高。PDTSBFQ器件的PCE最高，为5.92%，Voc为0.77 V， Jsc为12.25 mA cm−2，FF为0.63。初步结果提供了一种简单而有效的策略来设计用于有机太阳能电池的高性能二噻吩-喹诺啉聚合物供体。
Fluorinated quinoxaline units are attractive acceptor blocks for building low band gap photovoltaic polymers. In this contribution, two novel fluorinated quinoxaline-based copolymers, PCPDTBFQ and PDTSBFQ, have been successfully synthesized by combination of cyclopentadithiophene (CPDT) or dithienosilole (DTS) donor blocks in the polymeric backbones. The bridging atom effect shows a great influence on the absorption properties, energy level, carrier mobility as well as photovoltaic performance. PDTSBFQ with Si bridging atoms shows a little blue-shift in the UV-vis absorption, and a little larger band gap than PCPDTBFQ. However, PDTSBFQ shows a stronger aggregation even in the solution state. Compared with carbon, silica atoms afforded PDTSBFQ with a lower-lying HOMO level, suggesting a high Voc for polymer solar cells (PSCs). PDTSBFQ also exhibits better crystallinity and molecular ordering properties than PCPDTBFQ from the XRD study. The hole-only device based on PDTSBFQ exhibited a higher hole mobility of 1.5 × 10−5 cm2 V−1 s−1 than that of 4.1 × 10−6 cm2 V−1 s−1 for PCPDTBFQ. Conventional PSCs were fabricated to investigate the bridging atom effect on the photovoltaic properties of these two copolymers. Different interfacial layers (IFLs) of Ca and PFN had been tried to optimize the performance of the fabricated PSCs. When using a Ca/Al top electrode, PCPDTBFQ and PDTSBFQ devices showed PCEs of 2.16% and 4.43%, respectively. The better performance of the PDTSBFQ device can be attributed to the improvements in its Voc, Jsc and FF values just by choosing silica bridging atoms. After replacing the Ca/Al with a PFN/Al cathode, the performance of both PCPDTBFQ and PDTSBFQ devices was enhanced largely. The PDTSBFQ device achieved the highest PCE of 5.92% with a Voc of 0.77 V, a Jsc of 12.25 mA cm−2 and an FF of 0.63. The primary results gave a simple but efficient strategy to design high performance dithiophene-quinoxaline polymer donors for organic solar cell applications.