Modulating the Photoresponse of Transistor Memory with Perovskite Nanocrystals/Polyamic Acid as a Floating Gate

Recently, there has been growing interest among researchers in developing efficient photorecording devices using perovskite (PVSK) materials as floating gate layers due to their simplified structure and noncontact, light-responsive characteristics. Since a PVSK-based memory layer can reduce the operating voltage of the device, it can be used for nonvolatile memory applications. Herein, the p-type material pentacene was utilized as the charge transport layer, while methylammonium lead bromide PVSK nanocrystals (NCs) were employed as the floating gate memory layer. Four types of poly(amic acid) (PAA) polymers were synthesized in combination with PVSK for the memory layer. Compared to conventional polymers, PAA can further fine-tune the influence of energy-level alignment and the crystalline structure of PVSK NCs. The PAA structure consists of carboxylic acid and amide groups that can form Lewis acid–base interactions with PVSK NCs, while these hydrogen-bonding groups can interact with methylammonium to confine crystallite size, thereby passivating defects in PVSK NC films, providing structural stability and effectively optimizing device performance. Among the four synthesized PAA structures, sulfonyldianiline-cyclobutanetetracarboxylic dianhydride (SODA-CBDA) had a sulfone group and cyclobutane ring, possessing electron-withdrawing abilities that lowered the highest occupied molecular orbital level and a conjugation breaker that raised the lowest unoccupied molecular orbital level, resulting in a wider bandgap and stabilized electrons and holes compared to the other PAA structures. The fabricated device required only 1 s to complete electrical erasing and exhibited a stable and high ON/OFF current ratio (∼104) and long-term stability (>104 s) over consecutive device operations.