| 摘要: | 熱電材料是一種依賴於內部載子移動從而直接實現熱與電之間相互轉換的功能材料，在工廠廢熱發電、固態製冷和人體可穿戴設備等領域有著巨大的應用前景。有機熱電材料所具有的輕便、無毒、機械柔韌性高、原材料豐富易得、導熱係數低且易於工業大規模製備等優點。在目前研究的有機材料中，聚(3,4-亞乙基二氧?吩)聚苯乙烯磺酸鹽(PEDOT:PSS)可穩定分散在水中，形成的熱電薄膜具有良好的機械性能。但是原始的PEDOT:PSS薄膜熱電性能較差，導電度普遍低於 1 S cm-1，Seebeck係數只有 11-17 ?V K-1。所以要選取適當的方法對其熱電性能進行改質。本文通過對PEDOT:PSS體系摻雜具有雙重功能的離子液體，提升導電度的同時，提升材料的Seebeck係數。同時使用的1,3-二甲基咪唑陽離子(MMIM+)、1-乙基，3-甲基咪唑(EMIM+)、1-丁基，3-甲基咪唑(BMIM+)、1-己基，3-甲基咪唑(HMIM+)陽離子的四氟硼酸(BF4-)，和不同烷基側鏈長度的陽離子對PEDOT:PSS薄膜熱電性質提升的差異性。當使用2 mol L-1的MMIM BF4的甲醇溶液對PEDOT:PSS 熱電薄膜後處理時，薄膜Seebeck係數至24.4 μV K-1，導電度提升至1447.3 S cm-1，功率因數提升至86.34 μW m-1 K-2。使用馬倫哥尼效應(Marangoni Effect)，利用表面張力差將改質後的 PEDOT:PSS 薄膜轉印至不規則結構表面，在設定溫差為25 K時，得到10.4 nW的輸出功率，對應0.165 W m-2的功率密度。;Thermoelectric materials can directly realize the mutual conversion between heat and electricity by the movement of internal carriers and have huge application prospects in the fields of factory waste heat power generation, solid-state refrigeration, and human body wearable devices. Organic thermoelectric materials have unique advantages of lightness, non-toxicity, high mechanical flexibility, low thermal conductivity and easy industrial large-scale preparation. Among the organic materials currently studied, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) can be dispersed in water easily, and the film formed has great mechanical properties. However, the original PEDOT:PSS film has poor thermoelectric performance which the electrical conductivity is generally lower than 1 S cm-1, and Seebeck coefficient is only about 11-17 ?V K-1. Therefore, it is necessary to modify its thermoelectric performance. In this paper, the PEDOT:PSS system is doped with ionic liquid which carry binary charges to increase the conductivity and Seebeck coefficient at the same time. Simultaneously, to compare the influence of the improvement of thermoelectric properties of PEDOT:PSS films by cations with different alkyl side chain lengths, we used 1,3-dimethylimidazole (MMIM+), 1-Ethyl-3-methylimidazolium (EMIM+), 1-Butyl-3-methylimidazole (BMIM+), 1-Hexyl-3-methyl imidazole (HMIM+) cation of tetrafluoroborate (BF4-). When using 2 mol L-1 MIMM BF4 methanol solution to post-process the PEDOT:PSS thermoelectric film, the Seebeck of the film can be increased to 24.4 μV K-1, and the electrical conductivity increased to 1447.3 S cm-1, and the power factor value is increased to 86.34 μW m-1K-2. Then, using the Marangoni force-assisted method to spread micrometer-thick polymer films transferring to the surface of the special-shaped structure and make a flexible thermoelectric wristband. At a temperature difference of 25 K, a thermal power of 10.4 nW was obtained and the power density was 0.165 W m-2. |
