Plasma treatment is an environmentally friendly solution for modifying or nanostructuring the surface of several materials including photoactive polymers. The detailed characterization of the effect of plasma treatment on chemical and optoelectronic properties of photoactive polymers is, therefore, of specific interest. Herein, the effect of the exposure of poly(3-hexylthiophene) (P3HT) thin films to plasma created in three different gases (oxygen, argon and hydrogen) was studied. A range of spectroscopic techniques, such as x-ray (XPS) and ultraviolet (UPS) photoelectron spectroscopy in conjunction with UV–vis absorption, Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopies, are employed to quantify the extent of chemical modification occurring in each particular case. It is shown that oxygen plasma treatment leads to the disruption of the π-conjugation via the direct oxidation of the sulfur atom of the thiophene ring while the aliphatic side chain remains nearly unaffected. An oxidation mechanism is proposed according to which the sulfur atom of the thiophene ring is oxidized into sulfoxides and sulfones, which subsequently degraded into sulfonates or sulfonic acids in a relatively small degree. For argon and hydrogen plasma treatments some oxidation products are detected only at the polymer surface. In all cases the polymer surface Fermi level is shifted closer to the highest occupied molecular orbital (HOMO) energy after plasma treatment indicating p-type doping arising from surface oxidation.

等离子体处理是一种环境友好型解决方案，用于修饰或纳米结构化包括光敏聚合物在内的多种材料的表面。因此，等离子体处理对光敏聚合物的化学和光电性质的影响的详细表征是特别令人关注的。在本文中，研究了聚（3-己基噻吩）（P3HT）薄膜暴露于在三种不同气体（氧气，氩气和氢气）中产生的等离子体的影响。一系列光谱技术，例如X射线（XPS）和紫外（UPS）光电子能谱，结合紫外可见吸收，傅里叶变换红外（FTIR）和光致发光（PL）光谱技术，可以量化化学反应的程度在每种特定情况下都会发生修改。已经表明，氧等离子体处理通过噻吩环的硫原子的直接氧化而导致π共轭的破坏，而脂族侧链保持几乎不受影响。提出了一种氧化机理，根据该氧化机理，噻吩环的硫原子被氧化为亚砜和砜，随后以相对较小的程度降解为磺酸盐或磺酸。对于氩气和氢气等离子处理，仅在聚合物表面检测到一些氧化产物。在所有情况下，经过等离子体处理后，聚合物表面的费米能级都移近了最大占据分子轨道（HOMO）的能量，表明表面氧化产生了p型掺杂。