Functional polymeric materials with electrical bi-stable states possess significant potential for high-density data storage due to their nanoscale memory site, threedimensional-stacking ability and intrinsic flexibility. Aromatic polyimides bearing donor-acceptor (D-A) skeleton could form charge transfer complex (CTC) under electrical field, leading to their feasibility as memory materials. Three novel porphyrinated polyimides DATPP-DSDA, Zn-DATPP-DSDA and Mn-DATPP-DSDA were designed and synthesized for information memory applications. Metal ions with different electron configurations at 3d orbital have a determining influence on memory behaviors of polyimides: nonvolatile write-once-read-many-times memory (WORM) for DATPP-DSDA, volatile static random access memory (SRAM) for Zn-DATPP-DSDA, but no memory performance for Mn-DATPP-DSDA. By comparing the contribution of orbital transition and hole-electron distribution of charge-transfer excited states, roles of metal ions in regulating memory types were discussed. Molecular simulation results indicate that Zn ion could play a bridge role in paving the route for excited electrons from a D to A, while a trap role for Mn ion in hindering this process. This study proves the feasibility of the strategy for modulating the memory behaviors of porphyrinated polyimides by varying the central metal ion and provides the exact effects of various metal ions on regulating charge transfer processes.

Polyimide memory materials with a donoracceptor structure based on a charge-transfer mechanism exhibit great potential for next-generation information storage technology due to their outstanding high-temperature resistance and good dimensional and chemical stability. Precisely controlling memory performance by limited chemical decoration is one of core challenges in this field. Most reported work mainly focuses on designing novel and elaborate electron donors or acceptors for the expected memory behavior of polyimides; this takes a lot of time and is not always efficacious. Herein, we report a series of porphyrinated copolyimides coPIÀ Znx (x = 5, 10, 20, 50, 80), where x represents the mole percentage of Zn ion in the central core of the porphyrin. Experimental and theoretical analysis indicate that the Zn ion could play a vital bridge role in promoting the formation and stabilization of a charge-transfer complex by enhancing the hybridization of local and charge transfer (HLCT) excitations of porphyrinated polyimides, endowing coPIÀ Znx with volatile random access memory performance and continuously tunable retention time. This work could provide one simple strategy to precisely regulate memory performance merely by altering the metal content in porphyrinated polyimides.