Stabilization of Charge Carriers in Picket‐Fence Polythiophenes Using Dielectric Side Chains

Abstract

Insulated molecular wires (IMWs) are π-conjugated polymers that are molecularly sheathed with an insulating layer and are structurally analogous to electric power cords at the nanoscale. Such unique architectures are expected in molecular electronics and organic devices. Herein, we propose a new molecular design concept of IMWs, in which the sheaths can be customized, thereby enabling the modulation of the electronic properties of the interior π-conjugated systems. To this end, we focused our attention on the dielectric constant of the sheaths, as it governs the electrostatic interaction between charges. Upon doping, charge carriers, such as polaron and bipolaron, were generated regardless of the dielectric properties of the sheaths. Flash-photolysis time-resolved microwave conductivity measurements revealed that intrawire charge carrier mobility was independent of the sheaths. However, we found that the charge carriers could be stabilized by the sheaths with a high dielectric constant owing to the charge screening effect. We expect that IMWs designed in this way will be useful in a variety of applications, where the nature of charge carriers plays an important role, and particularly when redox switching is required (e.g., electrochromic, magnetic, and memory applications).

Transient Optical-Microwave Spectroscopy for Electron Mobility Assessment in Solids and Gels: A Comprehensive Approach

“…The electromagnetic waves, often referred to as microwaves, are herein employed for the measurement which has been applied for the measurement of mobility in conjugated polymers (intra-chain mobility) [21][22][23][24][25][26][27][28][29], conjugated organic supramolecular architectures [30][31][32][33][34][35][36][37][38][39][40], molecular crystals [41][42][43][44][45], conjugated organic frameworks [49][50][51], etc.…”

Landscape of Charge Carrier Transport in Doped Poly(3-hexylthiophene): Noncontact Approach Using Ternary Combined Dielectric, Paramagnetic, and Optical Spectroscopies

“…The spin states of the doped carriers in polythiophenes (PTs) have been investigated in previous works. − According to recent works, prerequisite charge carrier species in PTs have been considered and categorized as P, PP, − ,, and BP − on a single isolated chain of PT. The existence of the π-dimer, which is a pair of interacting Ps on two different chains in the solution − and condensed states, , has also been confirmed.…”

“…23 As for the carrier species in the solid state, the mechanism of the interchain interaction between charge carriers has not been fully understood to date. 41 To obtain clearer insight into the charge states, "insulated" PT, whose main chain is caged by electrically inactive side chains, 35,36,46 was studied. Because the interchain interaction was sterically hampered, they successfully observed the conversion of carrier species on isolated PT chains from Ps to PPs, followed by conversion into BPs.…”