Importance of Blade-Coating Temperature for Diketopyrrolopyrrole-based Thin-Film Transistors

Abstract

In this work, the e ff ect of blade-coating temperature on the electrical properties of a conjugated donor-acceptor copolymer containing diketopyrrolopyrrole (DPP)-based thin-film transistors (TFTs) was systematically analyzed. The organic semiconductor (OSC) layers were blade-coated at various blade-coating temperatures from room temperature (RT) to 80 degrees C. No remarkable changes were observed in the thickness, surface morphology, and roughness of the OSC films as the blade-coating temperature increased. DPP-based TFTs exhibited two noticeable tendencies in the magnitude of field-e ff ect mobility with increasing blade-coating temperatures. As the temperature increased up to 40 degrees C, the field-e ff ect mobility increased to 148% compared to the RT values. On the contrary, when the temperature was raised to 80 degrees C, the field-e ff ect mobility significantly reduced to 20.9% of the mobility at 40 degrees C. These phenomena can be explained by changes in the crystallinity of DPP-based films. Therefore, the appropriate setting of the blade-coating temperature is essential in obtaining superior electrical characteristics for TFTs. A blade-coating temperature of 40 degrees C was found to be the optimum condition in terms of electrical performance for DPP-based TFTs.