Ternary Memory Behavior of Carbazole-Based Donor–Acceptor Polymer and CdS NPs Composites

Multi-level memory can greatly improve information density, so it has been widely studied. In this study, a carbazole-based donor–acceptor polymer poly[2,7-9-(heptadecan-9-yl)-9 H -carbazole- alt -7 H -benzimidazo[2,1- a ]benz[ de ]isoquinolin-7-one] (PCz-BB) is synthesized, which exhibits flash-type ternary memory behavior. Further, CdS nanoparticles (NPs) are embedded into the prepared polymer to enhance the storage performance. The current–voltage ( I – V ) characteristics of memory devices based on PCz-BB:CdS composites and the effect of the embedding ratio of CdS NPs on the memory devices are studied. It is verified that the ON2/ON1/OFF current ratios of the devices at low CdS embedding concentrations are improved, and the threshold voltages are also reduced. The memory device based on the optimal embedding concentration (3 wt% CdS) exhibits a high ON2/ON1/OFF current ratio of 18631:72:1, a low threshold voltage of −0.40/−1.20 V, and excellent stability. The mechanism of resistive switching is explained by the theory of charge traps and conductive filaments. This work provides a new avenue for high-performance multi-level organic electrical storage materials.