The Mechanism of Dedoping PEDOT:PSS by Aliphatic Polyamines

The Mechanism of Dedoping PEDOT:PSS by Aliphatic Polyamines

Poly(3,4-ethylenedioxythiophene) blended with polystyrenesulfonate and poly(styrenesulfonic acid), PEDOT:PSS, has found widespread use in organic electronics. Although PEDOT:PSS is commonly used in its doped electrically conducting state, the ability to efficiently convert PEDOT:PSS to its undoped nonconducting state is of interest for a wide variety of applications ranging from biosensors to organic neuromorphic devices. Exposure to aliphatic monoamines, acting as an electron donor and Brønsted–Lowry base, has been reported to be partly successful, but monoamines are unable to fully dedope PEDOT:PSS. Remarkably, some—but not all—polyamines can dedope PEDOT:PSS very efficiently to very low conductivity levels, but the exact chemical mechanism involved is not understood. Here, we study the dedoping efficacy of 21 different aliphatic amines. We identify the presence of two or more primary amines, which can participate in an intramolecular reaction, as the key structural motif that endows polyamines with high PEDOT:PSS dedoping strength. A multistep reaction mechanism, involving sequential electron transfer and deprotonation steps, is proposed that consistently explains the experimental results. Finally, we provide a simple method to convert the commonly used aqueous PEDOT:PSS dispersion into a precursor formulation that forms fully dedoped PEDOT:PSS films after spin coating and subsequent thermal annealing.

聚（3,4 - 乙烯二氧噻吩）与聚苯乙烯磺酸盐和聚（苯乙烯磺酸）混合而成的PEDOT:PSS在有机电子学中得到了广泛应用。尽管PEDOT:PSS通常以其掺杂的导电状态使用，但将PEDOT:PSS高效地转变为其未掺杂的非导电状态的能力对于从生物传感器到有机神经形态器件等各种各样的应用都具有重要意义。据报道，暴露于作为电子供体和布朗斯特 - 劳里碱的脂肪族单胺在一定程度上是成功的，但单胺无法完全使PEDOT:PSS去掺杂。值得注意的是，一些（但不是所有）多胺能够非常有效地使PEDOT:PSS去掺杂至非常低的电导率水平，但所涉及的具体化学机制尚不清楚。在此，我们研究了21种不同脂肪族胺的去掺杂效果。我们确定存在两个或更多能够参与分子内反应的伯胺是赋予多胺高PEDOT:PSS去掺杂能力的关键结构特征。我们提出了一个涉及连续电子转移和去质子化步骤的多步反应机制，该机制能够合理地解释实验结果。最后，我们提供了一种简单的方法，将常用的水性PEDOT:PSS分散液转化为一种前体配方，该配方在旋涂和随后的热退火后能够形成完全去掺杂的PEDOT:PSS薄膜。