yl)ketone) has been reported by us having exciting thermal and optical bistability. 1 exhibits twostep thermo-induced reversible phase transition with T1/2(1) = 332 K and T1/2 (2) = 407 K along with reversible on/off photo-switching by 808 nm and 532 nm laser light. In this work, we explore the temperature-induced phase transition of 1 and its effect on the refractive index. By integrating 1 with an on-chip silicon photonic resonator, we observe a large thermo-optic resonance blue shift at room temperature that disappears at the phase transition temperature.