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Electric Transport Properties in PEDOT Thin Films
Published in John R. Reynolds, Barry C. Thompson, Terje A. Skotheim, Conjugated Polymers, 2019
Nara Kim, Ioannis Petsagkourakis, Shangzhi Chen, Magnus Berggren, Xavier Crispin, Magnus P. Jonsson, Igor Zozoulenko
Terahertz radiation is conventionally defined as light in the frequency range from 0.1 THz to 10 THz. It is an interesting range since it is at the boundary between electronics (microwaves) and photonics (infrared light).146 Because free charge carriers are sensitive to low energy excitation, low-energy THz radiation (1 THz corresponds to 0.00414 eV) can be used to probe their transport mechanisms in materials, including conducting polymers like PEDOT.147 Among THz characterization tools developed for the study of material properties, terahertz time-domain spectroscopy (THz-TDS) is currently the prevailing method.148 THz-TDS offers non-contact measurements of optical conductivity and permittivity of materials in the THz range, providing information about both free and localized charge carriers. The method has been widely used to characterize conducting polymers, including polyaniline, polypyrrole, polythiophene, and PEDOT.149–153
Introduction to Optical, Infrared, and Terahertz Frequency Bands
Published in Song Sun, Wei Tan, Su-Huai Wei, Emergent Micro- and Nanomaterials for Optical, Infrared, and Terahertz Applications, 2023
Song Sun, Wei Tan, Su-Huai Wei
Spectroscopy. Terahertz spectroscopy could provide valuable information in the fields of astronomy, materials science, and biochemistry. In particular, the terahertz time-domain spectroscopy (THz-TDS) is able to analyze samples that are opaque in the visible and near-infrared regimes. Though it requires the sample to be thin, THz-TDS yields coherent pulse radiation which contains abundant information in a broadband frequency range. In addition, terahertz waves are commonly used to study material properties in high magnetic fields, since the Larmor frequencies of electron spins are in the terahertz band.
Terahertz generation and detection of 1550-nm-excited LT-GaAs photoconductive antennas
Published in Journal of Modern Optics, 2021
Zhi-Chen Bai, Xin Liu, Jing Ding, Hai-Lin Cui, Bo Su, Cun-Lin Zhang
Among typical THz spectroscopy, terahertz time-domain spectroscopy (THz-TDS) is a very effective coherent detection technology [5]. THz wave generation and detection is a crucial technology. Presently, THz waves are mainly generated via optical rectification and photoconductive antennas. Optical rectification generates a low-frequency polarization field through the interaction between a pulsed laser and a non-linear medium to radiate THz. Optical rectification-generated THz waves are related to pulsed lasers and non-linear media [6]. Under the action of an ultrafast laser pulse and a bias electric field, photoconductive materials produce carriers, which accelerate and radiate THz waves. These THz waves are related to the photoconductive material, antenna structure, and ultrafast laser pulse width [7]. Photoconductive antenna-generated THz waves are usually stronger than optical rectification-generated ones because the THz energy generated via optical rectification only comes from the incident laser. In contrast, photoconductive antenna-generated THz waves are also related to the incident laser but can be adjusted by setting a bias voltage. With the development of semiconductor technology, photoconductive antennas [8,9] have attracted increased attention. Currently, gallium arsenide (GaAs), indium gallium arsenide (InGaAs), and indium aluminium arsenide (InAlAs) [10,11] are the main materials used in THz wave generation and detection research.