Multilevel Photonic Transistor Memory Devices Using Conjugated/Insulated Polymer Blend Electrets

Abstract

Photonic data storage has diverse optoelectronic applications such as optical sensing and recording, integrated image circuits, and multibit-storage flash memory. In this study, we employ conjugated/insulated polymer blends as the charge storage electret for photonic field-effect transistor memory devices by exploring the blend composition, energy level alignment, and morphology on the memory characteristics. The studied conjugated polymers included poly­(9,9-di-n-octylfluorenyl-2,7-diyl) (PF), poly­[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), poly­[{2,5-di­(3′,7′-dimethyloctyloxy)-1,4-phenylene-vinylene}-co-{3-(4′-(3″,7″-dimethyloctyloxy)­phenyl)-1,4-phenylenevinylene}-co-{3-(3′-(3′,7′-dimethyloctyloxy)­phenyl)-1,4-phenylenevinylene}] (SY-PPV), and poly­[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo­[2,1,3]­thiadiazol-4,8-diyl)] (F8BT), and the insulated polymers were polystyrene (PS) and poly­(methyl methacrylate) (PMMA). The photonic memory device using the PF/PS blend electret exhibited a dynamic switching behavior with light-writing and voltage-erasing processes both within only 1 s, along with a high contrast on the current on/off ratio between “Photo-On” and “Electrical-OFF” over 106 and the decent retention time for more than 3 months. In addition, the multilevel memory behavior could be observed using different light sources of 405, 450, and 520 nm or energy intensity, which was supported by surface potential analysis. The characteristics were superior to those of the devices using PF/PMMA blend due to the higher charge storage behavior of PS supported by fluorescence analysis. The PF/PS blend film prepared from the chlorobenzene solvent exhibited mesh-like and aggregated PF domains in the PS matrix and enhanced the contact surface area between the semiconductor and blend electret, leading to a higher memory window. The photonic memory behavior was also observed in the blend electrets of PS with the low band gap polymer, MEH-PPV, SY-PPV, or F8BT, by changing the photoresponsive light sources. Our study demonstrated a new electret system to apply on the multilevel photonic memory devices.

Multilevel storage and photoinduced-reset memory by an inorganic perovskite quantum-dot/polystyrene floating-gate organic transistor

“…According to the previous research, when the memory layer exists the microphase separation, the corresponding memory device displays a larger memory window. 15 In this work, as the ratio of CPB QDs and PS increases from 1 : 1 to 3 : 1, the phase separation emerges in the composite lm, as shown in Fig. S4.…”

“…Currently, it is a hot topic to explore the use of multilevel memory devices instead of single-level memory devices to achieve high-density data storage performance. 3,8,[12][13][14][15] However, the capability of storing multilevel information is one of the biggest challenges in memory technologies. 5,10,11,[15][16][17] Thus, there is an urgent demand to search for suitable NPs/QDs and organic semiconductor (OSC) channel materials for highly efficient, multilevel and endurable OFET memory devices.…”

Multiband Photoresponding Field‐Effect Transistor Memory Using Conjugated Block Copolymers with Pendent Isoindigo Coils as a Polymer Electret

“…[5][6][7][8] Especially, photonic FET memory, in addition to the aforementioned advantages, currently presents a high current contrast (10 5 ), fast programing time (<3 s), and prolonged retention time (>10 4 s), etc. [9][10][11][12] Many design strategies have been proposed concerning the plethora of the charge trapping materials including an organic-inorganic hybrid floating gate, [13,14] a conjugated/insulating polymer blends based floating gate, [15,16] rod-coil molecules with highly order layer structure, [17,18] donor-acceptor copolymers, [19][20][21] conjugated block copolymers (BCPs), [22] or charge-transfer supramolecules [23] as polymer electrets. Among them, polyfluorene (PF)-based BCPs are multifunctional with its favorable energy level adaption with channel materials like pentacene or dinaphthothienothiophene, and decent photoresponse along with their semiconducting properties.…”

High‐Performance Nonvolatile Organic Photonic Transistor Memory Devices using Conjugated Rod–Coil Materials as a Floating Gate

“…Also, the inherent bistable states or multi level storage can be achieved through modulating the charge density in an active channel by altering the external electric field or introducing photons. The use of floating-gate dielectrics, [18][19][20][21][22] polymer-based electrets, [23][24][25][26] and ferroelectric materials [27][28][29] as nonvolatile memories were employed in FET memory devices. In floating-gate-based FET memory devices, the nonvolatility characteristic was achieved by storing the charges in well-dispersed metallic or semiconducting materials that were located within an insulating gate dielectric layer.…”

“…[17,20,[30][31][32] However, organic-based photonic memory devices have been the subject of limited research compared to photoconductors and photodiodes. [33] Previous investigations have successfully prepared memory layers using organic-inorganic hybrid composites, [20,34,35] polymer nanoparticles [22] or small molecules [31,36,37] dispersed in an insulating polymer host, and direct casting of photoactive polymer electret. [25,38] The memory behavior due to light illumination within the devices originates from dissociating the photon-induced excitons that are employed for recombination or act as trapped charges.…”