Improving the Photoresponse of Transistor Memory Using Self-Assembled Nanostructured Block Copolymers as a Photoactive Electret

Abstract

With the explosive growth in data generation, phototransistor memory capable of multibit data storage with higher stability and switchability is highly desired to enhance the capacity of storage media. An innovative intrinsic dual-functional block copolymer (BCP)-based electret consisting of poly­(ethylene oxide)-block-poly­(1-pyrenemethyl methacrylate) (PEO-b-PPyMA) was used to elucidate the effect of the BCP design and self-assembled morphology on phototransistor memory. Regarding the constituent polymers in the BCP, PPyMA serves as the photogate, while PEO enhances the charge stability through electrostatic interaction. On the other hand, the solvent-annealed BCP film, representing well-defined hexagonal cylinders, shows an excellent charge trapping/stabilizing capability. Accordingly, the phototransistor memory, with PEO-b-PPyMA as an electret, produced a wide memory window (54 V), a superior memory stability (>106), and a fast photoresponsive characteristic. This research presents for the first time a new concept on the intrinsic dual-functional BCP to produce high-performance nonvolatile memory and demonstrates the potential of this approach for prospective application in optoelectronic devices.

Recent developments of block copolymers in nonvolatile memory and artificial synapses

“…99 Notably, BCP with self-assembled nanostructures can significantly promote the device performance and photoresponse of artificial synapses. BCPs are possible to combine disparate molecules into a single polymer, including all-conjugated, 100 conjugated/ insulating, 20,89,97,101 and insulating [102][103][104] BCPs. Therefore, BCPs can be applied as both electret and channel with charge-trapping capability.…”

Discotic Liquid Crystals with Highly Ordered Columnar Hexagonal Structure for Ultraviolet Light-Sensitive Phototransistor Memory

“…Recently, diverse electret design has been developed to improve the performance of phototransistor memory, including floating gate, − photoactive polymer, − and organic molecule electrets. ,, Floating gate electrets consist of dispersed photogates and photoinactive insulated polymer matrix. Photoactive polymer electrets are divided into two categories (i) conjugated/insulating polymer blends − and (ii) conjugated/insulating block copolymers. − With regards to the floating gate design, the device performance is usually hampered by the dispersity of photogates in a floating gate electret.…”

“…Photoactive polymer electret requires an elaborate design to address its poor affordability. Furthermore, the photoactive polymer electret possesses ambipolar charge-trapping propensity leading to an equivocally defined memory state and destructive readout, which will deteriorate the stability of the memory device. ,,− …”

Exploring the Charge-Trapping Behavior of Self-Assembled Sugar-based Block Copolymers with a Pendent Design in Photoassisted Memory

“…Diverse architectures of photoassisted memory devices have been introduced in the past few years and can be categorized into three types: floating gate, − photoactive polymer-based, − and ferroelectric photomemory. , The OFET memory based on a floating gate is particularly sensitive to the distribution of the trapping gates and precise size control within the memory layer, which limits the large-scale production for engineers . In contrast, polymer-based electrets are a more promising candidate owing to their mechanical endurance, also high compatibility with flexible and stretchable wearable electronics. , However, a synthesizing donor–acceptor system ,, and conjugated/insulated block copolymers (BCPs) − are hard to control and modify.…”