Covalent Functionalization of Black Phosphorus Nanosheets with Photochromic Polymer for Transient Optoelectronic Memory Devices

Abstract

How to erase sensitive data stored on memory devices quickly in an emergency has become a critical issue that needs to be addressed. Using BP-BIBB as a key template for atom transfer radical polymerization, which is prepared by the reaction of p-hydroxyphenyl-functionalized black phosphorous nanosheets (C6H4OH-BP) with 2-bromoisobutyryl bromide (BIBB), a highly soluble poly[4-(4-(3,3,4,4,5,5-hexafluoro-2-(2-methyl-5-phenylthiophen-3-yl)cyclopent-1-en-1-yl)-5-methylthiophen-2-yl)phenyl methacrylate] (PHPM)-covalently grafted BP derivative, hereafter abbreviated as PHPM-g-BP, is synthesized in situ. PHPM is a typical photochromic polymer that emits blue light under UV irradiation, while showing pale yellow under visible light illumination. By using PHPM-g-BP as an active layer, an as-fabricated transient optoelectronic memory device exhibits a nonvolatile rewritable memory effect under UV irradiation, with an ON/OFF current ratio of 3.6 × 103, a turn-on voltage of 1.60 V, and a turn-off voltage of −1.41 V. Upon visible light illumination for 10 s, all the information stored in the device is erased quickly. The observed device current drops down from 10−3 to 10−8 A rapidly.