Facile synthetic route to implement a fully bendable organic metal–insulator–semiconductor device on polyimide sheet

Abstract

Triblock copolymer surfactant, HO(CH2CH2O)20(CH2CH(CH3)O)70(CH2CH2O)20H (i.e. P123)-based nanocrystalline (nc)-TiO2 thin film had been synthesized on organic flexible polyimide (PI) sheet for their application in organic metal–insulator–semiconductor (MIS) device. The nc-TiO2 film over PI was successfully deposited for the first time by a systematic solution proceeds dip-coating method and by the assistance of triblock copolymer surfactant. The effect of annealing temperature (270°C, 5h) on the texture, morphology and time-induced hydrophilicity was studied by X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle system, respectively, to examine the chemical composition of the film and the contact angle. The surface morphology of the semiconducting layer of organic pentacene was also investigated by using AFM and XRD, and confirmed that continuous crystalline film growth had occurred on the nc-TiO2 surface over flexible PI sheet. The semiconductor–dielectric interface of pentacene and nc-TiO2 films was characterized by current–voltage and capacitance–voltage measurements. This interface measurement in cross-link MIS structured device yielded a low leakage current density of 8.7×10−12Acm−2 at 0 to −5V, maximum capacitance of 102.3 pF at 1MHz and estimated dielectric constant value of 28.8. Furthermore, assessment of quality study of nc-TiO2 film in real-life flexibility tests for different types of bending settings with high durability (c.a. 30days) demonstrated a better comprehension of dielectric properties over flexible PI sheet. We expected them to have a keen interest in the scientific study, which could be an alternate opportunity to the excellent dielectric–semiconductor interface at economic and low temperature processing for large-area flexible field-effect transistors and sensors.