Usefulness of Polar and Bulky Phosphonate Chain-End Solubilizing Groups in Polymeric Semiconductors

Abstract

A series of highly soluble copolymers (EH4P-Th, EH4P-Se, EH4P-TT, and EH4P-BT) based on phosphonate chain-end functionalized diketopyrrolopyrrole monomer and four different counterpart comonomers with varied electron-donating strength and conjugation length have been synthesized, characterized, and used in p-channel organic field-effect transistors (OFETs). It was found that introducing different counterpart comonomers into the main backbone alters the copolymers’ intrinsic properties, including absorption, frontier energy levels, molecular microstructure, and charge transport in OFETs. In OFETs fabricated on n-octadecyl­trimethoxysilane (OTS)-treated silicon (Si)/silicon dioxide (SiO2) surfaces, the copolymers exhibit good hole transport with maximum hole mobility (μh) of 1.46 × 10–1 cm2 V–1 s–1 in EH4P-TT, which is attributed to edge-on packing, fibrillar intercalating networks, and large crystalline π-stacking. More intriguing is the fact that high solubility and polarity of the resulting copolymers are induced via polar and bulky phosphonate chain-end groups, allowing for proper OFET operation using not only OTS-untreated Si/SiO2 substrates but also an eco-friendly 2-methyltetra­hydrofuran solution process. These results demonstrate promising applications of phosphonate chain-end groups in the design of conjugated polymers for various purposes.

Complementary Inverter Based on n‐Type and p‐Type OFETs with the Same Ambipolar Organic Semiconductor and ITO S/D Electrodes

“…OTS is always used in SiO 2 surface modification to change the hydrophobic state and improve the quality of semiconductor films. [44,45] Therefore, the substrate was modified by OTS in this study. The substrate (with ITO S/D electrodes and SiO 2 dielectric) was pre-modified by OTS with chemical vapor method before ITO modification and semiconductor deposition.…”

Current developments of eco-friendly organic field-effect transistors: from molecular engineering of organic semiconductors to greener device processing

“…2-MeTHF has a polarity similar to that of THF, so it can be chosen for dissolving almost any high-molecular-weight polymer material. 58,70,71 Vaccaro and co-workers developed an OFET device with a relatively low charge mobility of 0.01 cm 2 V À1 s À1 based on a material consisting of P3HT and processed using cyclopentylmethyl ether (CPME) as a solvent. 72,73 The Cao group reported the results of manufacturing polymer light-emitting diode and OFET devices using d-limonene, which is a non-chlorinated non-aromatic solvent.…”

“…61,66,79 On the other hand, Yang and co-workers deployed a high-polarity phosphonate group as a side chain to induce an edge-on orientation and form a molecule highly soluble in 2-MeTHF, a non-chlorinated solvent, resulting in more environmentally friendly solution processing. 71 Meanwhile, the Gagne group used a nature-inspired branched-chain engineering approach to incorporate galactose-containing moieties into semiconducting polymers to improve their processability in environmentally friendly solvents. The solubility of OSCs in alcohol-based solvents was improved by synthesizing novel isoindigo-based polymers with different relative amounts of galactose-containing side chains.…”

Recent Advances in Smart Organic Sensors for Environmental Monitoring Systems

“…Organic materials, ranging from small molecules to polymers, have various advantages such as excellent flexibility, , stretchability, , biocompatibility, , and suitability for low-cost mass production . A particularly fascinating aspect of organic materials for smart sensors is the capacity for properties such as tunable molecular interaction, , band gap, − and modulus − to be altered through molecular structural modifications that impart sensitivity and selectivity to the target stimulus. Additionally, because of their compatibility with many types of materials, these organic materials can be functionalized by other materials while maintaining their own properties (Figure ).…”