Microscopic Mobility of Polarons in Chemically Doped Polythiophenes Measured by Employing Photoluminescence Spectroscopy

Abstract

Doped conjugated polymers show high electrical conductivity due to doping-generated polarons, and understanding their transport properties is key to their practical use as transparent flexible electrodes. The transport properties have been widely studied in the field-effect transistor configuration, where the long-range transport affected by grain boundaries and conjugation breaks dominates. In contrast, spectroscopic measurements are sensitive to microscopic transport properties and have a potential to reveal the characteristic transport within an intrachain conjugation region. In this study, we show the photoluminescence of polarons in chemically doped polythiophenes to estimate microscopic carrier mobility through the relaxation dynamics of the photoexcited state of polarons. The estimated carrier mobility is 2 cm2 V–1 s–1 and larger than the reported highest value on the order of 0.1 cm2 V–1 s–1 in field-effect transistors. This study demonstrates the real-time observation of carrier diffusion and scattering in the conductive state of conjugated polymers.

Photoluminescence of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) in the visible region

“…11 In this paper, we report the PL from PEDOT/PSS in the visible region and its decay behavior in the femto-and picosecond time region. 11 In this paper, we report the PL from PEDOT/PSS in the visible region and its decay behavior in the femto-and picosecond time region.…”

“…[3][4][5][6][7][8] Indeed, as the doping level of PEDOT increases, electrical conductivity increases and absorbance in the visible region decreases. PEDOT/PSS shows strong absorption in the infrared region, 1,11 an indication of its narrow optical gap. The spectral position of the PL band can be roughly predicted by measuring the absorption spectrum.…”

“…11,13 The excitation light with a wavelength of 400 nm (3.10 eV) was obtained by the second harmonic generation of the output of the laser. The steady state PL spectra were obtained using a home-built measurement system with an excitation light of a CW laser diode at 402 nm (corresponding photon energy 3.08 eV).…”

Functionalized polythiophenes: Recognition materials for chemosensors and biosensors of superior sensitivity, selectivity, and detectability

“…Advantageously, the selectivity of chemosensors devised using MIP synthetic receptors is in many instances close to that of their biological A c c e p t e d M a n u s c r i p t 28 PT is much more extensive than that with derivatized PTs. Most likely, this trend will soon be reversed.…”

“…In doped PTs, two polaron states arise in the midgap region between the π and π* bands. Emergence of these states results in new optical transitions related to the two states in the infrared region and leading to optical transparency in the visible spectral range [3,28].…”