脂溶性導電高分子PEDOT常搭配水溶性的高分子PSS以增加在水中的分散性。然而PSS導電性差，因此降低了PEDOT:PSS膜的導電性。近年來許多研究者發現，將離子液體添加劑 (例如[BMIM]BF4) 參混PEDOT:PSS膜裡或是對膜進行後處理 (例如利用甲醇) 可以大幅增加膜的導電性。此研究主要探討導電性增加的原因。
我們利用小角度X光散射 (SAXS)、反射式小角度散射 (GISAXS)、X光反射率 (XRR) 與表面電位顯微鏡 (SPoM)等等儀器來探討PEDOT:PSS水溶液與其膜的結構。由SAXS分析中可知，PEDOT:PSS 水溶液主要是分散的奈米小橢球 (大約長24 nm，寬3 nm)。水溶液在有[BMIM]BF4 的存在下會有較多較大顆的聚集。由GISAXS和SPoM分析可得知，當我們的膜中有較多的[BMIM]BF4，他會大幅增加碎形結構 (fractal structure)，而碎形結構可以提供電子導通路徑進而增加膜的導電性。利用後處理所得到的膜也擁有較多的碎形結構，但是他們的特徵尺寸大約是36 nm，相對加入[BMIM]BF4的膜有超過微米的特徵尺寸來的小許多。
總體而言我們可以知道導電性增加與碎形結構的量成正相關，而後處理的膜擁有的小而多的碎形結構能夠增加彼此的接觸面積，比起少量大塊碎形結構能有更多的導電通路。

Poly(3,4-ethylene-dioxy-thiophene) (PEDOT) is an inherently hydrophobic and conductive polymer which usually doped with poly(styrene sulfonate) (PSS) for higher dispersity in aqueous solution. Nevertheless, PSS, a non-conductive polymer, inevitably lessens conductivity performance of PEDOT:PSS film. Plenty researchers have discovered that the conductivity of PEDOT:PSS films could be strongly enhanced upon minor presence of an ionic-liquid additive (such as [BMIM]BF4) in the dispersion or after post-deposition treatment with volatile solvent (such as methanol). The present study concerns the origin of this conductivity enhancement.
By use of small-angle X-ray scattering (SAXS), grazing incidence small-angle X-ray scattering (GISAXS), X-ray reflectivity (XRR) and surface potential microscopy (SPoM), here we report morphological differences in PEDOT:PSS solutions and corresponding films upon presence/treatment of selected additive/solvent. According to SAXS results, nano-ellipsoid (ca. 24 nm in length and 3 nm in width) are the dominant in aqueous solution and the existence of [BMIM]BF4 increases the population of big aggregates. GISAXS and SPoM results show that population of fractal clusters rises along concentration of [BMIM]BF4 in the film, which give rise to conduction paths in the film state. Fractal cluster formed as well after the film was treated with methanol, but with smaller correlation length (ca. 36 nm), in contrast to micron-size fractals in the former case.
We conclude that instead of the apparent phase separation or gel formation, the increased conductivity is mainly due to enhanced formation of fractal structure. Successive little fractal structures, formed after methanol treatment, provide more effective conduction-pathways comparing to huge fractal structures in identical volume.

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