High efficiency flexible organic light-emitting devices based on Pyronin B treated transparent PEDOT:PSS electrodes

The transparent electrodes have been extensively investigated due to possibility of potential applications for reality devices, smart surgical glasses, and smart windows. The inditum tin oxide (ITO) as traditional transparent electrode have the superior advantage of high transmittance and low sheet resistance. However, the fabrication cost of indium is high due to the exhaustion of indium materials, and ITO is not a good material for flexible electric devices due to the brittle property of ITO[1,2]. Therefore, research on the alternative transparent electrode have been conducted. Several material of transparent electrode such as conducting polymer, carbon nanotubes, graphene, and metal nanowires have been studied to replace the ITO transparent electrode. In particular, poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) have been considered as the alternative transparent electrode materials due to their having its mechanical flexibility, high conductivity, high transmittance, and low-cost solution processing [3,4,6]. Even though PEDOT:PSS is used as a hole injection layer for optoelectronic devices because of a high work function and good transparency, Pristine PEDOT:PSS has a low conductivity below 10 S/cm with comparison to the approximately 5000 S/cm of ITO conductivity [5,7]. The study on the enhancement of the conductivity for PEDOT:PSS transparent electrode have been extensively investigated. Recently, the conductivity of PEDOT:PSS was increased to 3000 S/cm by using sulfuric acid treatment. But, the sulfuric acid treatment has a disadvantage of substrate damage. To fabricate an efficient PEDOT: PSS transparent electrode, the replacing the acid treatment method of increasing the conductivity are needed. The most conductivity enhancement method is treated with polar organic compounds such as (DMSO), (DMF), resulting in the increases of the conductivity [9-13]. However, the enhanced conductivity of polar organic solvent treatment is lower than that of the acid treatment. The additional organic acids such as methanesulfonic acid is treated to enhance the conductivity. But, the problem such as high chemical activity and highly corrosive for other materials still remains. In this study, we demonstrates PEDOT:PSS electrode with two step treatment by using the common organic solvent and (Pyronin B). Additionally, organic light-emitting devices (OLEDs) based on the our highly conductive PEDOT:PSS electrode are fabricated. The current efficiency (25.3 cd/A, 100 cd/m2) of OLEDs based on the our highly conductive PEDOT:PSS electrode is larger than the that with pristine PEDOT:PSS (16.9 cd/A, 100 cd/m2).Maste