Year: 2016
Type: dissertation
Abstract: To address the need for better n-type organic semiconductors, thiophene-S,S-dioxidized \nindophenine (IDTO) was developed. IDTO is a planar quinoidal molecule with deep energy levels \nwhich facilitate stable and efficient electron transport. IDTO is a promising material in the design and \nfabrication of high performance n-type organic field-effect transistors because it offers simple \nsynthesis, as well as excellent processability and good performance. The work presented in this thesis \nfollows the development of IDTO and its various uses in organic field-effect transistors. Firstly, the \nsynthetic method for IDTO was systematically improved. Two important factors were improved, \nsafety was improved by replacing the solvent, benzene, with the much less hazardous toluene and the \nyield of the synthesis was increased from less than 10% to ~40%. Next, IDTO and two derivatives (5- \nbromo-IDTO and 6-bromo-IDTO) were synthesized and evaluated as new n-type small molecule \norganic semiconductors. The three compounds all exhibited unipolar n-type characteristics in the \nrange of 10-2 to 10-1 cm2V-1s-1. The highest electron mobility of 0.11 cm2V-1s-1 was measured for 6- \nbromo-IDTO. IDTO was then utilized as an electron accepting building block for the synthesis of two \ndonor-acceptor polymers: PIDTOBT and PIDTOBTz. Both polymers showed unipolar n-type \nperformance with electron mobilities on the order of 10-2 to 10-1 cm2V-1s-1. PIDTOBT had the highest \nelectron mobility of 0.18 cm2V-1s-1 after annealing at 200 °C. From the small molecule and polymer \nresults, it is clear that IDTO is a promising material for unipolar n-type organic semiconductors. Since \nIDTO has a strong electron accepting feature, it was thought that IDTO would have another use as an \nelectron trap. By blending IDTO with an ambipolar polymer that has a LUMO energy level above \nthat of IDTO; electron transport could be suppressed under the correct conditions. The three small \nmolecule IDTO compounds were blended with PINDFBT (TT) and PINDFBT (HH) to investigate the \nelectron trapping ability of IDTO. Complete suppression of electron transport was not observed but \nthe overall trend agreed with the theory. 6-bromo-IDTO having the lowest LUMO energy level \nshowed the strongest electron trapping effect while IDTO had the weakest effect due to its higher \nLUMO energy level. This thesis provides a comprehensive study of the development and application \nof the novel material, IDTO.
Source: UWSpace (University of Waterloo)
Author: Jackson Ellard
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2588660485