The effect of inorganic/organic dual dielectric layers on the morphology and performance of n-channel OFETs

Abstract

The optimization of dual dielectric layers by incorporating poly(vinyl alcohol) (PVA), poly(methyl methacrylate) (PMMA), polystyrene (PS) or poly(4-vinylphenol) (PVP) in combination with Al₂O₃ resulted in immensely improved OFET characteristics with N,N′-bis(cyclohexyl)naphthalene diimide (NDI-CY2) as the active material. The influence of the polymer dielectric layer on the growth morphology of NDI-CY2 and the structural characterization were investigated using atomic force microscopy (AFM) and thin film XRD analysis. The bottom-gate top-contact OFET devices fabricated on glass substrates with Al contact electrodes demonstrated excellent n-channel behavior in the presence of the Al₂O₃/PVA dual dielectric with the highest electron mobility (μ_e) value of 0.08 cm² V⁻¹ s⁻¹, threshold voltage (V_TH) as low as 0.5 V and current on/off ratio (I_ON/I_OFF) of 10⁴ with an operating voltage of 5 V respectively under vacuum.