Photophore‐Anchored Molecular Switch for High‐Performance Nonvolatile Organic Memory Transistor

Abstract

Over the past decade, molecular‐switch‐embedded memory devices, particularly field‐effect transistors (FETs), have gained significant interest. Molecular switches are integrated to regulate the resistance or current levels in FETs. Despite substantial efforts, realizing large memory window with a long retention time, a critical factor in memory device functionality, remains a challenge. This is due to the inability of an isomeric state of a molecular switch to serve as a stable deep trap state within the semiconductor layer. Herein, the study addresses this limitation by introducing chemical bonding between molecular switch and conjugated polymeric semiconductor, facilitating closed isomer of diarylethene (DAE) to operate as a morphologically stable deep trap state. Azide‐ and diazirine‐anchored DAEs are synthesized, which form chemical bonds to the polymer through photocrosslinking, thereby implementing permanent and controllable trapping states nearby conjugated backbone of polymer semiconductor. Consequently, when diazirine‐anchored DAE is blended with F8T2 and subjected to photocrosslinking, the resulting organic FETs exhibit remarkable memory performance, including a memory window of 22 V with a retention time over 106 s, a high photoprogrammable on/off ratio over 103, and a high operational stability over 100 photocycles. Further, photophore‐anchored DAEs can achieve precise patterning, which enables meticulous control over the semiconductor layer structure.

Hydrophilic Photocrosslinkers as a Universal Solution to Endow Water Affinity to a Polymer Photocatalyst for an Enhanced Hydrogen Evolution Rate

“…The synthetic route for these diazirine‐based crosslinkers is depicted in Figure S1 (Supporting Information). In specific, an intermediate, 4‐[3‐(Trifluoromethyl)‐3H‐diazirin‐3‐yl]benzoic acid, was synthesized following the method described by Sakurai et al [ 33 , 34 ] and then coupled with ethylene glycol, 1,11‐undecanediol, and tetraethylene glycol to produce the crosslinkers CL‐C2, CL‐C11, and CL‐TEG, respectively. Thus, the three crosslinker variants, CL‐C2, CL‐C11, and CL‐TEG, share a common functional group, yet they exhibit variations in their bridge chain lengths.…”

“…Notably, the HER rate observed in this study (564 µmol g −1 h −1 ) was somewhat lower than that reported in previous studies on F8BT, possibly owing to the presence of relatively low residual palladium content within F8BT nanoparticles (16 ppm, measured by inductively coupled plasma mass spectroscopy, ICP‐MS). [ 34 ] Furthermore, since the equivalent residual Pd in F8BT is the same as in each photocrosslinked photocatalysts, respectively, we speculated that the co‐catalytic effect of Pd would similarly influence the performance of each crosslinked F8BT nanoparticle. We also measured the performance of photocrosslinked F8BT nanoparticles over a wide range of optical wavelengths.…”

“…This is because cyclohexane has only one proton peak in its alkyl region in 1 H NMR, facilitating the analysis of the 12 protons involved during the C-H insertion reaction under UV light irradiation. [34] We included 1 H NMR and 19 F NMR spectra in the Supporting Information (Figures S15 and S16, Supporting Information), both before and after UV irradiation, demonstrating successful carbene insertion reactions with cyclohexane present in the system. As depicted in Figure S14 (Supporting Information), cyclohexane underwent C-H insertion from CL-C11 and the formation of CL-C11-cyclohexane complex via a photochemically induced C-H insertion reaction.…”