Flexible transparent electrodes based on intense pulsed light treatment of silver nanowires/PEDOT:PSS composites

Abstract

There is a growing demand for flexible, stretchable and transparent conductive films that can be used as electrodes or active layers in optoelectronic products, solar cells, solid electrolyte capacitors, wearables, sensors and actuators. Poly (3,4-ethylenedioxythiophene) poly (styrene sulfonate) (PEDOT:PSS) is an appropriate material for flexible electrodes because of its electrical conductivity and transparency. However, without treatment, it has insufficient electrical conductivity for the aforementioned applications. This study investigates a photonic thermal treatment method to improve the electrical conductivity of the PEDOT:PSS films. An intense pulsed light (IPL) system with tunable voltage and pulse duration was used for the evaporation of the residual moisture from the PEDOT samples after drying and partial removal of the PSS-rich shell, leading to higher electrical conductivity. Silver nanowires (AgNWs) were also added to improve electrical conductivity. IPL irradiation noticeably enhanced the electrical conductivity of both neat PEDOT:PSS and AgNWs/PEDOT:PSS composite samples. The electrical conductivity increased with respect to increases in the IPL voltage and number of exposures. However, exceeding some thresholds for the voltage and number of exposures degraded the electrical conductivity of the composite samples due to the breaking-up of the AgNWs. The IPL-treated PEDOT:PSS thick samples have a sheet resistance of 21.2 Ω/sq, approximately 424 times less than the untreated samples. For the composite samples, IPL irradiation decreased the sheet resistance to about half of that prior to the treatment. The results of various tests performed in this study indicate that the proposed IPL treatment can be considered as one of the approaches to efficiently overcome the limitations of PEDOT:PSS films regarding their insufficient electrical conductivity and poor adhesion to substrates.