Phthalocyanine‐Cored Star‐Shaped Polystyrene for Nano Floating Gate in Nonvolatile Organic Transistor Memory Device

Abstract

A novel non‐volatile organic memory device is developed based on an organic field effect transistor (OFET) with a dielectric layer of a four‐armed, star‐shaped polymer featuring a copper phthalocyanine (CuPc) core. The CuPc core unit of the star‐shaped polystyrene (CuPc‐PS4) self‐assembles to form aggregates via π–π interactions, which are isolated and dispersed in the polymer thin film. The OFET memory device employing CuPc‐PS4 shows significant hole‐trapping characteristics with a high memory ON/OFF current ratio of 107, long retention ability of over 104 s, and good endurance of more than 100 cycles, which is attributed to a flash‐type memory. The novel polymer design with CuPc core assemblies inside the polymer matrix is a promising candidate for nano floating gates in non‐volatile OFET memory.

High Performance Flexible Nonvolatile Memory Based on Vertical Organic Thin Film Transistor

“…Organic nonvolatile memory as an important and fundamental element of organic electronic devices has great potential to be used in a variety of novel applications, such as wearable electronics, human electronic skin, and rollable touch displays . Among the organic memory technologies, floating‐gate organic transistor memory (FGOTM) has attracted tremendous attentions due to its unique advantages, such as nondestructive read, sophisticated data‐storage mechanism, reliable long‐term data retention capacity, ultrahigh storage density, and easy compatibility with integrated circuits . Among the extensive research over the past decades, many efforts have been made on the study of structure of FGOTM and chargeable floating gate materials, including metal nanoparticles, semiconductor nanoparticles, small molecules, quantum dots, and carbon materials .…”

“…In the conventional planar FGOTM, the performance of the FGOTM was often limited by two intrinsic factors: the organic semiconductor materials and planar device structure. The intrinsically low carrier mobility of organic semiconductor materials (usually <2 cm 2 V −1 s −1 ) and the relatively long channel length (typically tens of micrometers) of planar FGOTM restricted the overall current density of the FGOTM and consequently the operating speed . Meanwhile, the appearance of little crack in the channel of the conventional planar FGOTM under mechanical bending would severely impact the lateral charge transport, leading to a device with poor mechanical stability .…”

4,5‐Diazafluorene‐Based Donor–Acceptor Small Molecules as Charge Trapping Elements for Tunable Nonvolatile Organic Transistor Memory

“…The electric‐programming time of TPA(PDAF) n (<20 ms) was suitable compared with other reported charge trapping elements, such as poly(α‐methylstyrene) (PαMS) (<1 µs),[3a] [2‐(9‐(4‐(octyloxy)phenyl)‐9H‐fluoren‐2‐yl)thiophene] 3 (WG 3 )(≈1 s), and diacetylenic‐naphthalenetetracarboxyldiimide‐carrying phosphonic acids (DAND‐PA) (18 s). [15b] The TPA(PDAF) n ( n = 1, 2, 3) owned the same hole trapping core TPA unit, and similar potential barrier (approximate HOMO levels) for hole carriers transferred, the widest memory windows of TPA(PDAF) 3 may be ascribed to the larger torsion angle of triphenylamine unit. As Figure S1 (Supporting Information) showed, the torsion angles of triphenylamine were 111°, 112°, 109° for TPA(PDAF) 1 , 108°, 109°, 113° for TPA(PDAF) 2 , and 122°, 113°, 125° for TPA(PDAF) 3 .…”

“…Through covalently linking between charge trapping cores and alkyl chains, Chen and co‐workers and Tao and co‐workers reported two new organic nanofloating gate elements and the memory devices showed long retention ability and good endurance. [15a,b] The new organic nanofloating gate structures through covalent linking showed obvious advantage compared with the conventional nanofloating gate memories, which generally use nanoparticles dispersed and isolated in a polymeric insulator. Considering the organic elements design experience, both charge trapping sites and unconjugated structures should be considered to realize charge concentration and distribution controllable.…”

Donor–Acceptor Core–Shell Nanoparticles and Their Application in Non‐Volatile Transistor Memory Devices

“…Non‐volatile organic field‐effect transistor (OFET) memory has been extensively investigated for use in flexible electronics due to their nondestructive read‐out operation, multibit storage capacity, and 3D stacking capability . OFET memory is made of a conventional transistor with an additional charge storage layer comprised of materials such as chargeable polymer electrets, ferroelectric materials, supramolecular electrets, and nanofloating gate dielectrics . Among these materials, nanofloating gate‐based OFET memory has the advantage of low power consumption as well as high memory density .…”