Composites of organic small molecules (OSMs) and single-walled carbon nanotubes (SWCNTs) have drawn great attention as flexible thermoelectric (TE) materials in recent years. Here, we synthesized thieno[2′,3′:4,5]thieno[3,2-b]thieno[2,3-d]thiophene (TTA) and 2,6-dibromothieno[2′,3′:4,5]thieno[3,2-b]thieno[2,3-d]thiophene (TTA-2Br) and compounded them with SWCNTs, obtaining thermoelectric TTA/SWCNT and TTA-2Br/SWCNT composites. The introduction of the electron-withdrawing Br group was found to decrease the highest molecular orbital energy level and bandgap (E_g) of TTA-2Br. As a result, the Seebeck coefficient (S) and power factor (PF) of the OSM/SWCNT composite films were significantly improved. Moreover, suitable energy barrier between TTA-2Br and SWCNTs facilitates the energy filtering effect, which further enhances thermoelectric properties of the 40 wt % TTA-2Br/SWCNT composite film with optimum thermoelectric properties (PF = 242.59 ± 9.42 μW m^–1 K^–2 at room temperature), good thermal stability, and mechanical flexibility. In addition, the thermoelectric generator (TEG) prepared using 40 wt % TTA-2Br/SWCNT composite films and n-type SWCNT films can generate an output power of 102.8 ± 7.4 nW at a temperature difference of 20 °C. This work provides new insights into the preparation of OSM/SWCNT composites with significantly enhanced thermoelectric properties.

中文翻译：

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通过将二溴取代的噻吩并苯与单壁碳纳米管复合来提高热电性能


近年来，有机小分子（OSM）和单壁碳纳米管（SWCNT）的复合材料作为柔性热电（TE）材料引起了广泛关注。在这里，我们合成了噻吩并[2',3':4,5]噻吩并[3,2-b]噻吩并[2,3-d]噻吩（TTA）和2,6-二溴噻吩[2',3':4 ,5]噻吩并[3,2-b]噻吩并[2,3-d]噻吩（TTA-2Br）并将其与SWCNT复合，获得热电TTA/SWCNT和TTA-2Br/SWCNT复合材料。研究发现，吸电子Br基团的引入降低了TTA-2Br的最高分子轨道能级和带隙(E _g )。结果，OSM/SWCNT复合薄膜的塞贝克系数（S）和功率因数（PF）显着提高。此外，TTA-2Br和SWCNT之间合适的能垒有利于能量过滤效应，进一步增强了40 wt% TTA-2Br/SWCNT复合薄膜的热电性能，具有最佳热电性能（PF = 242.59 ± 9.42 μW m ^–1 室温下），良好的热稳定性和机械柔韧性。此外，使用40wt％TTA-2Br/SWCNT复合薄膜和n型SWCNT薄膜制备的热电发电机（TEG）在20℃温差下可产生102.8±7.4nW的输出功率。这项工作为制备热电性能显着增强的 OSM/SWCNT 复合材料提供了新的见解。