Naphthodithiophenediimide-Bithiopheneimide Copolymers for High‐Performance n‐Type Organic Thermoelectrics: Significant Impact of Backbone Orientation on Conductivity and Thermoelectric Performance
Naphthodithiophenediimide-Bithiopheneimide Copolymers for High‐Performance n‐Type Organic Thermoelectrics: Significant Impact of Backbone Orientation on Conductivity and Thermoelectric Performance
复制标题
用于高性能n型有机热电材料的萘二噻吩二亚胺-联噻吩亚胺共聚物：主链取向对电导率和热电性能的显着影响
DOI：
10.1002/adma.202002060
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发表时间：
2020
影响因子：
29.4
通讯作者：
Kazuo Takimiya
中科院分区：
文献类型：
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作者：
Yang Wang;Kazuo Takimiya
具有高电导率的n型共轭聚合物(σ)的开发一直是有机热电材料(OTES)领域的一个巨大挑战。要实现高性能的OTES，必须对电荷-载流子输运有新的结构认识。本研究采用直接芳基化聚合的方法，合成了三种新型的由联二噻二亚胺(NDTI)和联苯并噻吩亚胺(BTI)单元组成的n型共聚物PNB、PNB-TZ和PNB-TzDP。通过将噻唑单元加入到主链中并调整侧链的支化点来改变主链的取向。主链取向从面朝向双峰的变化对聚合物的σ和功率因数(PF)有显著影响。结果表明，具有双峰取向的PnB-TzDP表现出高σ高达11.6 S cm−1和高pF高达53.4uW m−1K−2，这是迄今报道的溶液处理n掺杂共轭聚合物中最高的。进一步的研究表明，PNB-TzDP的双峰取向引入了三维导电通道，导致了更好的掺杂适应性，这应该是PNB-TzDP具有优异热电性能的关键因素。
The development of n‐type conjugated polymers with high electrical conductivity (σ) has continued to pose a massive challenge in organic thermoelectrics (OTEs). New structural insights into the charge‐carrier transport are necessitated for the realization of high‐performance OTEs. In this study, three new n‐type copolymers, named pNB, pNB‐Tz, and pNB‐TzDP, consisting of naphthodithiophenediimide (NDTI) and bithiopheneimide (BTI) units, are synthesized by direct arylation polymerization. The backbone orientation is altered by incorporating thiazole units into the backbone and tuning the branching point of the side chain. The alteration of the backbone orientation from face‐on to bimodal orientation with both face‐on and edge‐on fractions significantly impacts the σ and the power factors (PFs) of the polymers. As a result, pNB‐TzDP, with the bimodal orientation, demonstrates a high σ of up to 11.6 S cm−1and PF of up to 53.4 µW m−1K−2, which are among the highest in solution‐processed n‐doped conjugated polymers reported so far. Further studies reveal that the bimodal orientation of pNB‐TzDP introduces 3D conduction channels and leads to better accommodation of dopants, which should be the key factors for the excellent thermoelectric performance.