Biomass-Derived Degradable Poly(azomethine)s for Flexible Bistable Photonic Transistor Memories

We report on the synthesis and photonic memory applications of poly(azomethine)s (PAMs) synthesized from the condensation reaction ofbiomass-derived diamine, (3R,6S)-hexahydrofuro[3,2-b]furan-3,6-diyl bis(4-aminobenzoate) (ISBA) with photoactive 9,9-di-n-octylfluorene-2,7-dicarbox-aldehyde (FLDA) and biomass-based 2,5-furandicarboxaldehyde (FCA). Allthe prepared PAMs exhibited a higher thermal stability (Tg: 118-123 degrees C) andlower band gaps (Eg: 2.83-2.86 eV) compared with polymerP4(Tg: 102 degrees C,Eg: 3.11 eV) without the imine linkage due to chain rigidity and structuralcoplanarity. The organicfield effect transistor (OFET) memories usingP1-P4as the electrets showed a memory window of 17-25 V and a memory ratio ofup to 2.1x104with photowriting-electrical-erasing characteristics. Thediscrepancy in the energy level between the transporting layer and chargeable electret enabled the negative photoinduced excitonsstored in the electret. On the other hand, the increased ratio of the furan in the prepared PAM resulted in a higher highest occupiedmolecular orbital level, resulting in a larger memory window of 25 V. The imine linkages along the polymer backbone endowed ahigher lowest unoccupied molecular orbital level and provided a charge stabilizer to consolidate the trapped charges, which wassuperior to the polymer without the imine linkage. We further demonstratedflexible memory using biomass-based polymers as thesubstrate and the electret, and the memory characteristics were retained even after 1000 cycles of bending under a 5 mm bendingradius. By virtue of the degradable imine and ester linkages in the polymer chain, the PAM degraded into ISB biosegments underacidic conditions after 1 week. This result suggested that the prepared photoresponsive polyazomentines have the potential to be used for green electronics

Automated summary

This study reports on the synthesis and photonic memory applications of poly(azomethine)s (PAMs) derived from biomass. The prepared PAMs exhibited higher thermal stability and lower band gaps compared to polymers without the imine linkage. By using these polymers as electrets, high-performance organic field effect transistor memories with a large memory window and memory ratio were achieved. The flexibility and degradability of the polymers make them promising for use in flexible electronics.