Sustained Flexible Photonic Transistor Memories Based on Fully Natural Floating Gate Electrets

Photonic transistor memory with high-speed communicationand energy-savingcapabilities has emerged as a new data storage technology. However,most floating-gate electrets are composed of quantum dots derivedfrom petroleum or metals, which are either toxic or harmful to theenvironment. In this study, an environmentally friendly floating-gateelectret made entirely from biomass-derived materials was designedfor photonic memories. The results show that the photosensitive heminand its derivative protoporphyrin IX (PPIX) were successfully embeddedin a polylactic acid (PLA) matrix. Correspondingly, their disparatephotochemistry and core structure strongly affected the photosensitivityand charge-trapping capacity of the prepared electrets. With an appropriateenergy-level alignment, the interlayer exciton formed with the correctalignment of energy levels within the PPIX/PLA electret. In addition,the demetallized core offered a unique relaxation dynamic and additionaltrapping sites to consolidate the charges. Correspondingly, the as-prepareddevice exhibited a memory ratio of up to 2.5 x 10(7) with photo-writing-electrical-erasing characteristics. Conversely,hemin demonstrated self-charge transfer during relaxation, makingit challenging for the device to store the charges and exhibit a photorecoverybehavior. Furthermore, the effect of trapping site discreteness onmemory performance was also investigated. The photoactive componentswere effectively distributed due to the high dipole-dipoleinteraction between the PLA matrix and PPIX, resulting in a sustainedmemory performance for at least 10(4) s after light removal.The photonic memory was also realized on a bio-derived dielectricflexible substrate. Accordingly, a reliable photorecording behaviorwas observed, wherein, even after 1000 cycles of bending under a 5mm bending radius, the data was retained for more than 10(4) s. To our knowledge, it is the first time that a two-pronged approachhas been used to improve the performance of photonic memories whileaddressing the issue of sustainability with a biodegradable electretmade entirely from natural materials.