High‐Performance Organic Phototransistor Memory Utilizing a Brønsted Acid Charge‐Transfer Mechanism

ABSTRACT Organic phototransistor memory has emerged as a pivotal technology for developing future flexible optoelectronics and multifunctional logic circuits. However, the practical performance of these devices is often limited by unstable charge‐trapping environments within the donor–acceptor (D–A) system. In this work, a series of D–A systems based on polymer donors, poly(2‐naphthylmethacrylate) (PNMA) and poly(9‐anthracenyl methyl methacrylate) (PAMA), paired with three different electron acceptors, including 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F 4 TCNQ), tris(pentafluorophenyl)borane (BCF), and BCF(H 2 O) are used as the electret layer in the phototransistor memory. This comprehensive study systematically evaluates the impact of various charge‐transfer mechanisms on memory characteristics. Notably, compared to the integer‐charge‐transfer (F 4 TCNQ) or Lewis‐acid‐type (BCF) systems, the Brønsted acid‐type complex BCF(H 2 O)PAMA, driven by a unique protonation mechanism, exhibits the strongest charge modulation and effectively stabilizes charge within the electret layer. Consequently, this system demonstrates superior photoresponse and memory stability in the phototransistor memory device, achieves an exceptional I ON / I OFF of approximately 10 5 –10 6 with a remarkably short illumination time of only 1 s or a significantly low operating voltage of −1 V. This work highlights that leveraging the Brønsted acid mechanism is an effective strategy for achieving highly stable optoelectronic memory.