Highly sensitive ethylene glycol-doped PEDOT–PSS organic thin films for LPG sensing

Abstract

In this study, for the first time we report the fabrication of low-cost ethylene glycol (EG)-doped PEDOT-PSS (poly 3,4-ethylenedioxythiophene:polystyrene sulfonate) organic thin film sensors for the detection of LPG at room temperature. The prepared thin films were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy and thermogravimetric analysis (TGA) techniques for the analysis of their structural and morphological features. The doping of EG strongly improved the conductivity of pure PEDOT-PSS films by three orders of magnitude. The gas sensing responses of pristine and doped PEDOT-PSS thin films were investigated at room temperature by fabricating a sensor device on an ITO-coated glass substrate. The gas sensing characteristics of the prepared thin films were investigated for liquified petroleum gas (LPG), dimethyl propane, methane and butane test gases. The EG-doped PEDOT-PSS thin films exhibited excellent sensitivity for all the test gases, especially towards LPG, at room temperature. The sensitivity of the doped PEDOT-PSS films was recorded to be >90% for LPG with improved response and recovery time. The stability study indicated that the sensing response of doped PEDOT-PSS thin films was highly stable over a period of 30 days. Due to enhanced sensitivity, stability and fast response and recovery times, these EG-doped PEDOT-PSS thin films can be used in gas sensor technology, especially towards the detection of LPG at room temperature.

High performance flexible supercapacitors based on secondary doped PEDOT–PSS–graphene nanocomposite films for large area solid state devices

“…Further, the bright regions in the AFM image of pure PEDOT-PSS thin lm are assigned to highly conductive PEDOT content and the dark regions correspond to insulating PSS-rich domains. 35…”

“…In our previous works, we have demonstrated that, the post treatment of PEDOT-PSS lms using polar organic solvents with high boiling points can signicantly enhance the conductivity of PEDOT-PSS aqueous dispersions by 2-3 orders of magnitude. [34][35][36][37] In this study ethylene glycol (EG) is used as a solvent for the post treatment to enhance the conductivity of pristine PEDOT-PSS and PEDOT-PSS/rGO nanocomposites. Post treatment of EG into PEDOT-PSS/rGO leads to phase segregation of PEDOT and PSS, reduces the coulombic interactions between PEDOT and PSS phases.…”

“…There have been several reports on enhancing the conductivity of PEDOT-PSS by secondary doping using different additives such as DMSO, EG, glycerol and sorbitol. [33][34][35] Recently, in our previous works we have demonstrated that, effect of post treatment using these solvents enhances the conductivity of PEDOT-PSS by several orders of magnitude. [35][36][37] The post treatment using the additives not only enhances the conductivity but also improves the electrochemical performance of PEDOT-PSS based nanocomposites.…”

“…[33][34][35] Recently, in our previous works we have demonstrated that, effect of post treatment using these solvents enhances the conductivity of PEDOT-PSS by several orders of magnitude. [35][36][37] The post treatment using the additives not only enhances the conductivity but also improves the electrochemical performance of PEDOT-PSS based nanocomposites. 38 Reduced graphene oxide in recent past emerged as a promising candidate for fabrication of ultrathin carbon electrode materials due to its high conductivity, large specic surface area (2630 m 2 g À1 ), chemical stability, 39 high electron mobility at room temperatures 40 and excellent mechanical stability [41][42][43][44] has been extensively studied to prepare the composites for supercapacitor fabrication.…”

Fabrication and Characterization of Humidity Sensors Based on Graphene Oxide–PEDOT:PSS Composites on a Flexible Substrate

“…It is important to note that the layout with thinner fingers actually helped to increase the parallel resistance of the sensors, but minimally modified their sensitivity. Moreover, as occurred with the capacitance of the sensors, in all cases, their sensitivity decreased as the frequency increased, due to the decrease in dielectric constant for both GO and PEDOT:PSS with respect to increasing frequency [46,48]. Furthermore, the highest sensitivity was obtained for an intermediate concentration of PEDOT:PSS since, although it helped to improve the sensitivity at higher RH values, if the concentration was too high, the performance of the sensors at low RH values As analyzed before, the changes in the impedance were ruled by the resistance behavior (see Figure 5).…”