Bulky side chain effect of poly(N‐vinylcarbazole)‐based stacked polymer electrets on device performance parameters of transistor memories

Abstract

Three poly(N-vinylcarbazole) (PVK)-based polymer electrets were synthesized through Friedel-Crafts postfunctionalization for the function of charge storage in nonvolatile organic field effect transistor (OFET) memory devices. The bulky side chain effect of these stacked polymer electrets on the morphology, water contact angles, and memory characteristics were examined with regard to those of precursor PVK. The introduction of steric hindrance groups could interrupt the large length of p-stacked structures in PVK and block the form of region-regular structures from region-random on external electric field. As a result, the memories based on the three modified polymers exhibited approximate memory windows of 32 V increased by 13 V with respect to PVK. Besides, the writeread-erase-read cycles stability of the modified polymers was superior to that of PVK. Furthermore, we found that the holes were mainly located in the region of local p-stacked structures and bulky p-conjugated groups also acted as additional electron trapping sites. Molecular engineering of charge trapping site with tunneling polymers will be a promise strategy for the advance of transistor memory.

Effect of Acceptor Unit Length and Planarity on the Optoelectronic Properties of Isoindigo–Thiophene Donor–Acceptor Polymers

“…Of all six polymers, iI-3T showed the highest hole mobility [(4.1 ± 0.4) × 10 –3 cm 2 V –1 s –1 ]; this is unsurprising, given that it has the highest donor/acceptor ratio and also the highest HOMO energy of all six polymers. The charge carrier mobility of bis-iI-T is similar to that reported by Jiang et al (μ h = 3.0 × 10 –3 cm 2 V –1 s –1 , and μ e = 3.7 × 10 –3 cm 2 V –1 s –1 ); the small difference is likely due to different interchain packing, resulting from the different alkyl substituents used. − The polymer with the highest electron mobility [(2.3 ± 0.3) × 10 –3 cm 2 V –1 s –1 ] was di-iI-3T , again highlighting the impact of adding additional electron acceptors to the polymer repeat unit.…”

Charge‐Storage Aromatic Amino Compounds for Nonvolatile Organic Transistor Memory Devices

“…The endurance characteristics of the WRER cycle were carried out both under dark condition with the writing gate voltage of −80 V and the reading gate voltage of −40 V for PyPN memory device and −20 V for PN memory device. The erasing process was conducted under illumination without applying gate voltage . As shown in Figure a,b, the rewritable memory characteristics could remain stable along with 150 continuous writing, reading, and erasing cycles.…”

3D Steric Bulky Semiconductor Molecules toward Organic Optoelectronic Nanocrystals

“… The most distinctive feature of 3D steric bulky molecules is the existence of a tetrahedral sp 3 -hybridized carbon spiro-center and two connected planar π-systems (Figure C). ,, The typical 3D steric bulky molecules mainly include diarylfluorenes (DF) , and spirocyclic aromatic hydrocarbons (SAHs), similar to spirobifluorene (SBF), spiro­[fluorene-9,9-xanthene] (SFX), , spiro­[fluorene-9,7′-dibenzo­[c,h]­acridine]-5′-one (SFDBAO) . As one of the superstars of organic semiconductors, the 3D steric bulky molecules with excellent optoelectronic performance and impressive stability have been extensively used in organic light-emitting diodes (OLEDs), − organic field-effect transistors (OFET), miniaturized lasers, − solar cells, memory devices, − and other fields, the solar-to-electric power conversion efficiency of the perovskite solar cells (PSCs) based on 3D steric bulky molecule also reached up to 20%. − …”