In‐Situ Photoelectron Spectroscopy Study on the Air Degradation of PEDOT:PSS in Terms of Electrical and Thermoelectric Properties
Dong‐Jin Yun, Jaemin Jung, Young Mo Sung, Hyemin Ra, Jung‐Min Kim, JaeGwan Chung, Se Yun Kim, Yong‐Su Kim, Sung Heo, Ki‐Hong Kim, Yong Jin Jeong, Jaeyoung Jang
Abstract
Abstract Despite excellent electrical and mechanical properties, practical application of poly(3,4‐ethylenedioxythiophene) polymerized with poly(4‐styrenesulfonate) (PEDOT:PSS) face the challenge of ensuring air stability in electronic industry. Here, degradation mechanism of PEDOT:PSS‐based films in air is clearly demonstrated through X‐ray/ultraviolet photoelectron spectroscopy (XPS/UPS) and its depth‐profiling technique. As the duration of air‐exposure increases, the PEDOT:PSS‐based films alter molecular structures with the formation of SO x bond in PEDOT and CN x bond growth, changing ratios of insulating part (PSS − , PSSH, oxidized PEDOT) to conducting part and deteriorating their electrical conductivities. These transition behaviors are similar in all PEDOT:PSS‐based films regardless of additives such as dopant or multi‐walled carbon nanotube. Additionally, methanol treatment to various PEDOT:PSS‐based films for inducing conformational change between PEDOT and PSS molecules, partly restore the electrical properties of the denatured PEDOT:PSS films. Finally, thermoelectric properties of the PEDOT:PSS‐based films are characterized by investigating the effects of air‐aging and methanol treatment on electrical conductivities, Seebeck coefficients, and power factors. To sum up, this study provides a useful guideline for establishing a strategy to ensure air stability of PEDOT:PSS‐based films by clarifying the degradation mechanism and property recovery methods.