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Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has been used extensively in the fabrication of polymer light-emitting diode (PLED) displays by drop-on-demand (DoD) inkjet printing technique to enhance charge carrier injection and transportation.In order to make a good thin-film with high uniformity,it is crucial to control the drying behavior of inkjet printed PEDOT:PSS droplets because an inkjet droplet is quite different from a macroscopic liquid such as a spin-coated film in the evaporation behavior.In this work,the thickness profile and 3D shape of single ejected PEDOT:PSS droplets of ~10pL at ~3m/s ejection speed after impact on the oxygen plasma treated indium-tin-oxide (ITO) coated glass substrate were examined.The variations of maximum drop spreading area,center height and edge gradient with the temperature of the substrate were also investigated.Results show that while the evaporation rate of a micro-fluid is high due to its very large surface-to-volume ratio,the drying behavior is sensitive to the temperature of the substrate.There exists an appropriate range of temperatures to obtain a good drop with sharp edge and flat surface.On the other hand,as the temperature of the substrate exceeds a limit,a ring-like structure was observed.Results from this experiment would be considered as a reference to achieve uniform film with a flat surface and a well-defined edge after droplet drying,and has potential to be applied in the modeling of drop impact.