Influence of Backbone Regioregularity on High-Mobility Conjugated Polymers Based on Alkylated Dithienylacrylonitrile

Abstract

We designed and synthesized two donor–acceptor type conjugated polymers, the regioirregular polymer RI-PDPP-CNTVT-6 and its regioregular counterpart RR-PDPP-CNTVT-6, based on diketopyrrolopyrrole (DPP) and alkylated dithienylacrylonitrile (CNTVT) units. Among them, the 2-decyltetradecyl side chain on the DPP acceptor unit and the hexyl side chain on the CNTVT donor unit were used to ensure enough solubility for them. The backbone regioregularity was used to tune electronic structures and carrier transport of the conjugated system. The two conjugated polymers were characterized for their thermal, photophysical, electrochemical, and solution-processable properties, thin-film microstructures, and morphologies. The top-gate bottom-contact configuration organic field-effect transistor (OFET) devices based on these two conjugated polymers showed excellent ambipolar performances. Remarkably, the regioirregular polymer RI-PDPP-CNTVT-6 exhibited higher charge-carrier mobilities than the regioregular counterpart polymer RR-PDPP-CNTVT-6 did, as their highest hole/electron mobilities (μhmax/μemax) were 1.48/1.27 and 0.48/0.052 cm2 V–1 s–1, respectively. Moreover, the influence of backbone regioregularity on its thermal stability, electrochemical and photophysical properties, solution processability, and charge-carrier mobility was intensively studied. Our results afforded a promising pathway toward the development of excellent ambipolar OFETs with high performance, good solution processability, and thermal stability.

Improving Bias-Stress Stability of p-Type Organic Field-Effect Transistors by Constructing an Electron Injection Barrier at the Drain Electrode/Semiconductor Interfaces

“…Thermionic emission is a common model to describe the electron injection at room temperature, which has been applied successfully for organic semiconductors with metal contacts. Thermionic emission model follows an Arrhenius-type relationship 45 = * − Δ i k j j j y { z z z J A E kT exp (7) where J is the injection current and A* = 4πqm*k 2 T 2 /h 3 . Here, m* is the effective mass of electron in the metal, k is the Boltzmann constant, h is Planck's constant, and T is the operational temperature (298 K).…”

“…Organic field-effect transistors (OFETs) as key components of organic electronics have been researched for the applications in displays, sensors, identification tags, and so on. − The past several decades have witnessed huge success in high-performance OFETs. The carrier mobility of p-type OFETs is now comparable to or even better than that of silicon-based transistors. − However, the consumerization of OFETs still suffers challenges because of their significant bias-stress instability. Bias-stress instability of OFETs manifests as a shift of threshold voltage and a decrease in drain current over operation time, which leads to gradual malfunctioning of devices in real applications. − For instance, a liquid crystal display driven by an OFET might not turn on/off appropriately because of the threshold voltage shift.…”

Recent progress in lactam‐based polymer semiconductors for organic electronic devices

“…Yu et al compared the performance of the OFET fabricated using the regioregular polymer P70 with that using the regioirregular polymer P71 containing the alkylated dithienylacrylonitrile (CNTVT) and DPP units (Figure 5). 35 The surface morphologies of P70 and P71 were studied. It was observed that regioirregular P71 was rougher than regioregular P70.…”

Diketopyrrolopyrrole-based conjugated polymers containing planar benzo[c]cinnoline and tetraazapyrene structures for high-performance and long-term stable triboelectric nanogenerators

“…[29][30][31] In particular, the electronic properties of such polymers can be engineered easily through chemical modification. [32][33][34] Furthermore, most conjugated polymers can be soluble in common solvents. The unique advantages of conjugated polymers open up a new avenue for diverse applications, including organic fieldeffect transistors (OFETs), [35][36][37][38] organic photovoltaic cells (OSCs), [39][40][41] and organic light-emitting diodes (OLEDs).…”