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

Abstract

With unique advantages and features, photonic organic field-effect transistor memory has gained widespread attention over extensive research fields in recent years. In this work, we report the synthesis and device characteristics of three different sugar-based block copolymers, where each contains a pendent maltose (Mal) block and a pendent photoluminescent arene (anthracene (AN), carbazole (CZ), and fluorene (FL)) on a norbornene backbone polymerized through metathesis ring opening polymerization. The corresponding block copolymers are introduced as a polymer electret layer in the photoassisted memory. The hydrophilic maltose block paves the way for self-assembled morphology (ordered vertical cylinder and horizontal cylinder nanostructures) via solvent annealing, while the hydrophobic and photoluminescent arenes act as the charge-trapping site. The optical, electrochemical, and morphological properties were investigated to understand the impact on device performance. The photoassisted memory devices were electrically written by gate bias of −60 V for 1 s and recovered with three kinds of light sources (254-, 365-, and 530 nm lights). Among the studied devices, Mal-b-AN exhibited excellent memory performance with rapid photoresponse owing to the favorable energy levels’ alignment and morphological orientation. Accordingly, the device produced a high memory ratio (>106) over 104 s, a stable performance over 45 endurance cycles, and a wide memory window (∼35 V). This study not only established a detailed explanation of the nanostructures and energy level effect on the memory behaviors of sugar-based block copolymers with a pendent design but also provides an approach for the next-generation optoelectronic devices using green materials.