Enhancement of the thermoelectric properties of PEDOT:PSS thin films by post-treatment
Enhancement of the thermoelectric properties of PEDOT:PSS thin films by post-treatment
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DOI：
10.1039/c3ta11209h
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发表时间：
2013-01-01
影响因子：
11.9
通讯作者：
Gessner, Thomas
中科院分区：
文献类型：
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作者：
Luo, Jinji;Billep, Detlef;Gessner, Thomas
研究了聚（3，4-乙撑二噻吩）：聚苯乙烯磺酸盐（PEDOT：PSS）薄膜的室温热电性能。不同的方法已被应用于调整TE性能：第一次添加极性溶剂，二甲基亚砜（DMSO），到PEDOT：PSS溶液;第二后处理的薄膜与DMSO和离子液体的混合物，1-乙基-3-甲基咪唑四氟硼酸盐（EMIMBF 4）。它被证实，DMSO后处理是更有效的比DMSO添加在改善电导率与微小的变化，塞贝克系数。对于具有DMSO后处理的膜，功率因数增加到30.1 μ W mK（-2），而通过DMSO添加的优化功率因数为18.2 μ W mK（-2）。结果表明，DMSO的加入和后处理诱导形态变化：一个互连的网络细长的PEDOT颗粒生成，导致更高的电导率。相比之下，对于在EMIMBF 4存在下后处理的那些膜，产生了具有增加的极化子密度的短的和圆形的PEDOT晶粒的互连网络，导致塞贝克系数的改善和伴随的电导率的折衷。当EMIMBF 4的体积分数为50%时，获得了38.46 μ W·mK（-2）的最佳功率因数，这是迄今为止PEDOT：PSS薄膜的最高功率因数。假设热导率为0.17 W mK（-1），则在300 K时相应的ZT为0.068。这些结果表明，后处理是一种很有前途的方法，以提高PEDOT：PSS薄膜的TE性能。此外，离子液体，EMIMBF 4，显示了通过一个更环保的过程来调整PEDOT：PSS薄膜的TE性能的潜力。
In this work, the thermoelectric (TE) properties of poly(3,4-ethylenedioxylthiophene):poly(styrene sulfonate) (PEDOT:PSS) thin films at room temperature are studied. Different methods have been applied for tuning the TE properties: 1st addition of polar solvent, dimethyl sulfoxide (DMSO), into the PEDOT: PSS solution; 2nd post-treatment of thin films with a mixture of DMSO and ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4). It is verified that DMSO post-treatment is more efficient than DMSO addition in improving the electrical conductivity with a trivial change in the Seebeck coefficient. The power factor is increased up to 30.1 mu W mK(-2) for the film with DMSO post-treatment, while the optimized power factor by DMSO addition is 18.2 mu W mK(-2). It is shown that both DMSO addition and post-treatment induce morphological changes: an interconnected network of elongated PEDOT grains is generated, leading to higher electrical conductivity. In contrast, for those films post-treated in the presence of EMIMBF4, an interconnected network of short and circular PEDOT grains with increased polaron density is created, resulting in the improvement in the Seebeck coefficient and a concomitant compromise in the electrical conductivity. An optimized power factor of 38.46 mu W mK(-2) is achieved at 50 vol% of EMIMBF4, which is the highest reported so far for PEDOT: PSS thin films to our knowledge. Assuming a thermal conductivity of 0.17 W mK(-1), the corresponding ZT is 0.068 at 300 K. These results demonstrate that post-treatment is a promising approach to enhance the TE properties of PEDOT: PSS thin films. Furthermore, ionic liquid, EMIMBF4, shows the potential for tuning the TE properties of PEDOT: PSS thin films via a more environmentally benign process.