Relationship between Resistivity and Structure of Photosensitive Organic Silsesquioxanes by Impedance Spectroscopy and Solid-State29Si Nuclear Magnetic Resonance

Novel photosensitive insulating materials comprising of organic silsesquioxane (OSQ) have been developed. The OSQ had the high photosensitivity, insulating performance, transparency, and heat resistance required for a passivation layer of semiconductors in thin-film-transistor liquid crystal displays (TFT-LCDs). A passivation layer is needed for high resistivity to ensure the electrical stability of TFT-LCDs. We analyzed the electrical properties and local structures by impedance spectroscopy and solid-state 29Si nuclear magnetic resonance (NMR). The impedance Cole–Cole plots and frequency-dependent dielectric constants (e') at 20 and 60 °C were obtained by impedance spectroscopy of Al/OSQ/Al multilayer substrates. Cross polarization/magic angle spinning (CP/MAS) 29Si NMR analyses of OSQ samples showed that the condensation reaction did not occur by UV irradiation. The condensation occurred during baking processes above 150 °C. The NMR analyses also showed the behaviors of various ionic migration species detected by impedance spectroscopy.