Thermoelectric and Charge Transport in Doped Semi-Crystalline Polymers
type: CreativeWork
description: In recent years, organic semiconductors (OSCs) have generated many research interests from both academia and industry due to the exotic properties and potential applications in flexible displays, light-emitting diodes, solar cells as well as thermoelectrics. Compared with their inorganic counterparts, OSCs have several advantageous features including low cost, lightweight, mechanically robustness, ease of synthesis and tailoring material properties, environmental friendless, flexibility. For many of the mentioned applications, OSCs are doped to improve the conductivity. This is particularly important to improving the thermoelectric performance of OSCs and the figure of merit ZT. However, another equally important parameter, the Seebeck coefficient, tends to decrease when carrier concentration and conductivity increase. Therefore, it is crucial to find a balanced point where ZT maximizes. To achieve this, it is paramount to understand charge and entropy transport as well as the related key parameters affecting the electrical and thermoelectric properties in doped OSCs. Herein, doped poly(2,5-bis(3-tetradecylthiophen2-yl)thieno-[3,2-b]thiophene), PBTTT and its derivates are selected in this thesis for the investigation of thermoelectric and charge transport in highly conducting polymers. An unprecedented doping regime can be achieved via ion-exchange doping method, which is already approaching the metal-insulator (M-I) transition. The enhanced charge delocalization has been evidenced by the systematic spectroscopic as well as transport studies for samples with a broad range of conductivities. The clear Hall effect has been detected by a high-resolution ac Hall set-up, with the heavily doped sample showing a temperature-independent Hall coefficient, which indicates nearly "ideal" band-like transport. The temperature dependences of conductivity and Seebeck coefficient for samples at different doping levels witness the onset of metallic states evolved from pure hopping t…
abstract: In recent years, organic semiconductors (OSCs) have generated many research interests from both academia and industry due to the exotic properties and potential applications in flexible displays, light-emitting diodes, solar cells as well as thermoelectrics. Compared with their inorganic counterparts, OSCs have several advantageous features including low cost, lightweight, mechanically robustness, ease of synthesis and tailoring material properties, environmental friendless, flexibility. For many of the mentioned applications, OSCs are doped to improve the conductivity. This is particularly important to improving the thermoelectric performance of OSCs and the figure of merit ZT. However, another equally important parameter, the Seebeck coefficient, tends to decrease when carrier concentration and conductivity increase. Therefore, it is crucial to find a balanced point where ZT maximizes. To achieve this, it is paramount to understand charge and entropy transport as well as the related key parameters affecting the electrical and thermoelectric properties in doped OSCs. Herein, doped poly(2,5-bis(3-tetradecylthiophen2-yl)thieno-[3,2-b]thiophene), PBTTT and its derivates are selected in this thesis for the investigation of thermoelectric and charge transport in highly conducting polymers. An unprecedented doping regime can be achieved via ion-exchange doping method, which is already approaching the metal-insulator (M-I) transition. The enhanced charge delocalization has been evidenced by the systematic spectroscopic as well as transport studies for samples with a broad range of conductivities. The clear Hall effect has been detected by a high-resolution ac Hall set-up, with the heavily doped sample showing a temperature-independent Hall coefficient, which indicates nearly "ideal" band-like transport. The temperature dependences of conductivity and Seebeck coefficient for samples at different doping levels witness the onset of metallic states evolved from pure hopping t…
author: Chen, Chen
language: eng
keywords: Organic thermoelectrics, Doping, Charge transport
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/a72bae6f-8cec-410a-8b97-5f1b69200476/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2020-05-13
date modified: 2026-07-22T22:24:24Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.54804