Grain boundary engineering of organic semiconductor films in organic transistors

Abstract

Organic field‐effect transistors (OFETs) show great application potential in organic electronic and optoelectronic fields due to their excellent mechanical flexibility, low cost, and solution processing. However, grain boundaries (GBs) disrupt the aggregation state of organic semiconductor (OSC) films and hinder electrical performance and stability, which limits the application of OFETs. Besides, the sensitive nature of GBs is widely used in sensing, but detailed descriptions of the GBs are scarce. This review aims to fill this knowledge gap. The role of GBs and their effect on the performance and stability of OFETs are analyzed, followed by a detailed summary of the characterization of GBs. Then, strategies for suppressing the negative effects of GBs and utilizing the sensitive nature of GBs for application are proposed. Finally, potential research directions for GBs in OFETs are discussed.

Thiopyran-Fused Polycyclic Aromatic Compounds Synthesized via Pt(II)-Catalyzed One-Pot Ring-Expansion and 6-endo Cyclization Reactions

“…After the solvent was removed under vacuum, the mixture was separated and purified by column chromatography eluted with PE to give 4 (0.45 g) in an 85% yield as a yellow oil. (6). Under a nitrogen atmosphere, compound 4 (1.40 g, 4.60 mmol) was dissolved in dry THF (50 mL) and the solution was cooled to −78 °C.…”

“…S-fused polycyclic aromatic hydrocarbons (PAHs) have gained much attention due to their widespread applications in optoelectronic devices, such as light-emitting diodes, 1,2 organic photovoltaics, 3,4 and field-effect transistors. 5,6 Among various S-containing heterocycles, the five-membered thiophene ring is one of the most representative building blocks. 7−10 The fused thiophene ring in PAHs can be simply introduced by locking two single-bond-linked segments with a sulfur atom.…”

“…S-fused polycyclic aromatic hydrocarbons (PAHs) have gained much attention due to their widespread applications in optoelectronic devices, such as light-emitting diodes, , organic photovoltaics, , and field-effect transistors. , Among various S-containing heterocycles, the five-membered thiophene ring is one of the most representative building blocks. − The fused thiophene ring in PAHs can be simply introduced by locking two single-bond-linked segments with a sulfur atom. − Alternatively, S-fused PAHs can be synthesized via conventional cyclization reactions from thiophene-containing precursors. − For example, 1-ethynyl-2-thienyl-substituted aromatics can be converted to benzo­[ b ]­thiophene undergoing classic 6- endo cyclization reaction with the assistance of transition-metal-based catalysts (Figure a), such as indium, − ruthenium, aurum, and platinum. , In comparison to the abundant synthetic methodologies toward S-fused PAHs containing five-membered thiophene rings, fewer reports have focused on their analogues consisting of six-membered thiopyran rings, − most likely due to their different electronic structures and more challenging syntheses. Since thiopyran-fused PAHs present intriguing optoelectronic properties, − such as near-infrared absorption, low oxidation potential, and high charge carrier mobility, the construction of thiopyran-fused PAHs still remains challenging.…”

Control over the aggregated structure of donor–acceptor conjugated polymer films for high‐mobility organic field‐effect transistors

“…In addition to the chemical structure, the aggregated structure of D‐A conjugated polymers is also important for charge transport. [ 26–28 ] For semi‐crystalline P3ATs, it is proposed that high crystallinity, low π–π stacking distance ( d π–π ), well connected crystalline domains, alignment of films along the channel direction, etc., are critical for high charge mobility. [ 29,30 ] These principles have also been used to guide the control of the aggregated structure of D‐A conjugated polymers.…”

Cross-Linked Interfacial Layer for Enhanced Performance in n-Channel Organic Thin Film Transistors

“…In recent years, organic thin-film transistors (OTFTs) have attracted considerable attention due to their potential for the application in light-weight, mechanically flexible, and solution processable large-area electronics. − Owing to the development of organic semiconductors (OSCs) and device optimization, the carrier mobility and device stability of OTFTs have achieved significant progress. − The highest hole mobility of p-type OTFTs has been boosted to over 30 cm 2 V –1 s –1 . − Specifically, though being left behind that of p-type OTFTs, the mobility of n-type OTFTs has also been greatly improved to reach over 10 cm 2 V –1 s –1 . − In addition to the tailoring of the OSC structures and employment of various dielectric layers, equally important is the interfacial engineering in OTFT devices, as coined by the Nobel laureate Herbert Kroemer, “the interface is the device”. In general, these interfaces may induce grain boundaries, traps, and other defects, which are negative for the charge transport and lead to nonideal device performance. ,− …”