Tuning the photocurrent responsive and resistive switching performances of stilbazolium/iodoargentate hybrids by modulating the aggregation mode among chromophores

• Published in: CrystEngComm 2023-01, Vol.25 (4), p.632-64
• Main Authors: Chen, Jing-Jing, Huang, Chang-Qi, Yi, Hong-Mei, Lv, Zhou-Lin, Wu, Wei, Zheng, Hui-Dong, Li, Hao-Hong
• Format: Article
• Language: English
• Subjects: Agglomeration; Anions; Chromophores; Memory devices; Molecular orbitals; Molecular structure; Photoelectric effect; Photoelectric emission; Photoluminescence; Stacking; Switching
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/d2ce01609e

The study about the effect of the stacking mode on the photo/electrical performance of crystalline organic/inorganic hybrids will be beneficial for the design of new photo/electrically active materials. In this work, D-π-A stilbazolium-type chromophores bearing novel ortho-N -alkyl substituents were synthesized and incorporated with iodoargentates to generate three crystalline stilbazolium/iodoargentate hybrids, i.e. , [(CMAMP)(Ag 2 I 3 )] n ( 1 ), [(HMAMP)(Ag 2 I 3 )] n ( 2 ), and [(HMAHP) 2 (Ag 5 I 7 )] n ( 3 ). When the substitutes on the amine group range from -C 2 H 5 CN (for CMAMP + ) to -C 2 H 5 OH (for HMAMP + ), the same (Ag 2 I 3 ) n n − anions will be produced, and the π π stacking interactions among stilbazoliums will be observed from absence to presence (weak head-to-head H-aggregation). Furthermore, when the substituent on the ortho-N of pyridine was also set as -C 2 H 5 OH (for HMAHP + ), more electron-rich (Ag 5 I 7 ) n 2 n − anion can be generated, and strong head-to-tail H-aggregation among HMAHP + cations will happen. The enhanced aggregation strengthening in 3 can lead to its larger blue-shift photoluminescence, higher photocurrent, and better resistive switching performance (much higher ON/OFF ratio of 4.51 × 10 2 ). Their binary resistive switching mechanism can be explained as the SCLC model, and the better photo/electrical performances of 3 stem from its stronger head-to-tail H-aggregations, more negatively charged (Ag 5 I 7 ) n 2 n − anion, and stronger (Ag 5 I 7 ) n 2n − -HMAHP + interaction. The highly delocalized π antibonding orbitals between the empty p-orbitals of ethylene in its LUMO of (HMAHP) 2 2+ dimer of 3 also support this conclusion. The good structure-property correlation based on accurate structural information in these stilbazolium/iodoargentate hybrids will be beneficial for the design of next-generation memory devices. D-π-A stilbazolium-type dyes with substitutes ranging from -C 2 H 5 CN to -C 2 H 5 OH were incorporated with iodoargentates to generate three hybrids, whose photo/electrical performance will be enhanced greatly by modulating aggregation modes.