Sustained Flexible Photonic Transistor Memories Based on Fully Natural Floating Gate Electrets
Chun‐Kai Chen, Jin‐Chieh Ho, Chih‐Chien Hung, Wei‐Cheng Chen, Wei-Cheng Chen, Toshifumi Satoh, Wen‐Chang Chen, Wen‐Chang Chen · ACS Applied Materials & Interfaces · 2023
Photonic transistor memory with high-speed communication and energy-saving capabilities has emerged as a new data storage technology. However, most floating-gate electrets are composed of quantum dots derived from petroleum or metals, which are either toxic or harmful to the environment. In this study, an environmentally friendly floating-gate electret made entirely from biomass-derived materials was designed for photonic memories. The results show that the photosensitive hemin and its derivative protoporphyrin IX (PPIX) were successfully embedded in a polylactic acid (PLA) matrix. Correspondingly, their disparate photochemistry and core structure strongly affected the photosensitivity and charge-trapping capacity of the prepared electrets. With an appropriate energy-level alignment, the interlayer exciton formed with the correct alignment of energy levels within the PPIX/PLA electret. In addition, the demetallized core offered a unique relaxation dynamic and additional trapping sites to consolidate the charges. Correspondingly, the as-prepared device exhibited a memory ratio of up to 2.5 × 10 7 with photo-writing-electrical-erasing characteristics. Conversely, hemin demonstrated self-charge transfer during relaxation, making it challenging for the device to store the charges and exhibit a photorecovery behavior. Furthermore, the effect of trapping site discreteness on memory performance was also investigated. The photoactive components were effectively distributed due to the high dipole–dipole interaction between the PLA matrix and PPIX, resulting in a sustained memory performance for at least 10 4 s after light removal. The photonic memory was also realized on a bio-derived dielectric flexible substrate. Accordingly, a reliable photorecording behavior was observed, wherein, even after 1000 cycles of bending under a 5 mm bending radius, the data was retained for more than 10 4 s. To our knowledge, it is the first time that a two-pronged approach has been used to improve the performance of photonic memories while addressing the issue of sustainability with a biodegradable electret made entirely from natural materials.