Multistimuli-Responsive Plasticity Transitions of a Phototransistor Conferred by Using Thermoresponsive Polyfluorene Block Copolymers

Photonic transistor memory has drawn extensive research attention owing to its noncontact programming capability, rapid data transmission, and low power consumption. In this research, a series of thermoresponsive poly(fluorene)-block-poly(N-isopropylacrylamide) (PF-b-PNIPAAm) with varied compositions were employed as an electret layer for photomemory application. Accordingly, the device presented ambipolar charge trapping with a decent memory ratio of ∼105 and a large memory window of ∼30 V by applying electrical and photoprogramming. More importantly, the photomemory exhibited a higher data retention stability at 40 °C, which was attributed to the conformational reorganization of PF-b-PNIPAAm at a temperature over its lower critical solution temperature. Finally, the phototransistor was modulated as a photosynapse to emulate fundamental functions, including the short-term and long-term plasticity. This research opens up possibilities in polymer-based memory under photo-/thermal-operations to realize human-like optical processing for neuromorphic computing systems.