Effect of ozone plasma on the electronic properties of PEDOT:PSS

The effects of ozone-induced oxidation, in the presence/absence of high energy ultraviolet (UV) light, on the electronic property of highly conductive PEDOT:PSS were systematically examined by varying treatment times of UV–ozone (UVO) and ozone (O3). In this study, the changes in the conductivity, work function, and surface wetting property of the material are studied while the UVO/O3 exposure is made at 0 (without treatment), 4, and 8 min. Our results indicated that both treatments enhanced electrical conductivity, and its enhancement by the UVO/O3 tends to be observed in the entire temperature range, 100–350 K, particularly at 8 min exposures. In addition, the UVO/O3 treatment resulted in increasing surface energy (reducing water contact angle) and the work function of the polymer. UVO treatment more effectively reduced the water contact angle, signifying a greater increase in the surface energy. In contrast, O3 treatment demonstrated a more pronounced enhancement of electrical conductivity and work function of the polymer than that of the UVO. The observed differences in electronic/conductivity property changes by the UVO vs O3 exposures tend to originate from the variations in altering the chemistry of the polymer, the oxidation mechanism by the plasma methods, and the distinct effect of the methods in the polymer chain altering/alignment of the material. The UVO/O3 method’s capability in enhancing the conductivity and tuning the work function of the polymer has vital implications for device interface engineering, mainly allowing for optimized charge carrier injection/extraction. Thus, this study highlights the importance of PEDOT:PSS surface modification through UVO/O3 treatments so as to improve the electrical and surface properties of the polymer for a potential application in optoelectronic device performance improvements.