Atoyo Jonathan, Burton Matthew R, McGettrick James, Carnie Matthew J
SPECIFIC-IKC, Materials Research Centre, College of Engineering, Swansea University, Bay Campus, Swansea SA1 8EN, UK.
Polymers (Basel). 2020 Mar 3;12(3):559. doi: 10.3390/polym12030559.
A two-step approach of improving the thermoelectric properties of Poly(3,4-ethylenedioxythiophene)poly(4-styrenesulfonate) (PEDOT:PSS) via the addition of the ionic liquid, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM:TFSI) and subsequent reduction with NaBH is presented. The addition of 2.5 v/v% of EMIM:TFSI to PEDOT:PSS increases the electrical conductivity from 3 S·cm to 1439 S·cm at 40 °C. An additional post treatment using the reducing agent, NaBH, increases the Seebeck coefficient of the film from 11 µV·K to 30 µV·K at 40 °C. The combined treatment gives an overall improvement in power factor increase from 0.04 µW·m·K to 33 µW·m·K below 140 °C. Raman and XPS measurements show that the increase in PEDOT:PSS conductivity is due to PSS separation from PEDOT and a conformational change of the PEDOT chains from the benzoid to quinoid molecular orientation. The improved Seebeck coefficient is due to a reduction of charge carriers which is evidenced from the UV-VIS depicting the emergence of polarons.
本文提出了一种两步法来改善聚（3,4-乙撑二氧噻吩）聚（4-苯乙烯磺酸盐）（PEDOT:PSS）的热电性能，即先添加离子液体1-乙基-3-甲基咪唑双（三氟甲基磺酰）亚胺（EMIM:TFSI），随后用硼氢化钠（NaBH）进行还原。在PEDOT:PSS中添加2.5 v/v%的EMIM:TFSI，可使40℃时的电导率从3 S·cm提高到1439 S·cm。使用还原剂NaBH进行额外的后处理，可使薄膜在40℃时的塞贝克系数从11 μV·K提高到30 μV·K。在140℃以下，联合处理使功率因数从0.04 μW·m·K提高到33 μW·m·K，实现了整体改善。拉曼光谱和X射线光电子能谱测量表明，PEDOT:PSS电导率的增加是由于PSS与PEDOT分离以及PEDOT链从苯型到醌型分子取向的构象变化。塞贝克系数的提高是由于电荷载流子的减少，这从紫外可见光谱中极化子的出现得到了证实。
