Adjustment of charge trap number and depth in molecular backbone to achieve tunable multilevel data storage performance

A series of conjugated donor-acceptor (D-A) molecules with the electron-rich unit triphenylamine (TPA) as donor and azobenzene chromophore and/or cyano group as acceptors were successfully synthesized. Acceptors varying in number and electron-withdrawing strength were incorporated into the molecular backbone to investigate the impact on device switching behavior. It is found that the data storage states and memory effects are highly dependent on the number and strength of the electron-deficient groups. The devices based on the D-pi-A1-pi-A2 molecule with two electron-withdrawing groups exhibited excellent ternary memory behavior, while those based on the D-pi-A1 or D-pi-A2 molecule containing one electron-accepting moiety showed binary memory characteristics. In addition, the bistable memory effects of TPAVC 2 and TPAAH 3-based data storage devices varied from WORM to flash when the acceptor changed from a cyano group to an azobenzene chromophore. Therefore, tunable multilevel memory device performance has been achieved by adjusting the number and electron-withdrawing strength of acceptor moieties in the molecular backbone, offering guidance for the rational design of superior D-A molecules for high density data storage (HDDS) applications.