Carbohydrate-based block copolymers with sub-10 nm face-centered cubic nanostructures for low-power-consuming and ultraviolet light-triggered synaptic phototransistors

Addressing environmental concerns and producing sustainable and environmentally friendly electronic devices with low power consumption poses a significant challenge. This study introduces phototransistor devices employing morphologically controlled block copolymers based on maltotriose, maltoheptaose, and beta-cyclodextrin as polymer electrets. Ordered self-assembled morphologies can be achieved by utilizing microwave radiation for rapid annealing (within 5 s) with optimized annealing conditions. Herein, face-centered cubic (FCC), vertical, and mixed cylindrical nanostructures are reported. The resulting well-defined morphologies play a pivotal role in enhancing the electron-trapping capability of the block copolymers and facilitating charge carrier transport between the electret and semiconducting layers. Consequently, the phototransistor memory manifests exceptional performance, featuring stability and endurance. Intriguingly, the cavity of beta-cyclodextrin provides a stable environment for the trapped charges, leading to a larger memory window than other block copolymers. On the other hand, a device consisting of MT-b-PS exhibited superior current contrast exceeding 106 even under a low drain voltage of -1 V, attributed to sub-10 nm FCC nanostructures. Furthermore, this phototransistor device successfully emulated the synaptic functions of sensing, learning, and short- and long-term memory in the human brain, along with a low energy consumption of 0.312 fJ. Hence, this report opens the pathways for developing promising bio-based electronic devices.