Dually crosslinkable SiO2@polysiloxane core–shell nanoparticles for flexible gate dielectric insulators

Abstract

A hybrid gate dielectric material for flexible OTFT is developed by using core–shell nanoparticles (SiO₂@PSR_XL) where the core and the shell consist of silica nanoparticles and polysiloxane resin, respectively. Since polysiloxane resin contains both thermal- and photo-crosslinkable functional groups, densely-crosslinked thin gate dielectric films can be easily prepared on various substrates by conventional solution casting followed by dual crosslinking. SiO₂@PSR_XL films exhibit high thermal stability (weight loss at 300 °C is smaller than 3 wt%). The dielectric films made of SiO₂@PSR_XL show an exceptionally low leakage current and no breakdown voltage up to 4.3 MV cm⁻¹, which are comparable to those of silica dielectrics prepared by CVD. OTFT devices based on dibenzothiopheno[6,5-b:6′,5′-f]thieno[3,2-b]thiophene (DTBTT) as a semiconductor and SiO₂@PSR_XL as a gate dielectric exhibit good hole mobility (2.5 cm² V⁻¹ s⁻¹) and I_on/I_off ratio (10⁶).