Thiophene-S,S-dioxidized indophenine for use in organic field effect transistors

organic field effect transistor

Ellard, Jackson

University of Waterloo

关键词: organic field effect transistor;   

Others  :  https://uwspace.uwaterloo.ca/bitstream/10012/11137/1/Ellard_Jackson.pdf

瑞士|英语

来源: UWSPACE Waterloo Institutional Repository

【 摘 要 】

To address the need for better n-type organic semiconductors, thiophene-S,S-dioxidizedindophenine (IDTO) was developed. IDTO is a planar quinoidal molecule with deep energy levelswhich facilitate stable and efficient electron transport. IDTO is a promising material in the design andfabrication of high performance n-type organic field-effect transistors because it offers simplesynthesis, as well as excellent processability and good performance. The work presented in this thesisfollows the development of IDTO and its various uses in organic field-effect transistors. Firstly, thesynthetic method for IDTO was systematically improved. Two important factors were improved,safety was improved by replacing the solvent, benzene, with the much less hazardous toluene and theyield of the synthesis was increased from less than 10% to ~40%. Next, IDTO and two derivatives (5-bromo-IDTO and 6-bromo-IDTO) were synthesized and evaluated as new n-type small moleculeorganic semiconductors. The three compounds all exhibited unipolar n-type characteristics in therange of 10-2 to 10-1 cm2V-1s-1. The highest electron mobility of 0.11 cm2V-1s-1 was measured for 6-bromo-IDTO. IDTO was then utilized as an electron accepting building block for the synthesis of twodonor-acceptor polymers: PIDTOBT and PIDTOBTz. Both polymers showed unipolar n-typeperformance with electron mobilities on the order of 10-2 to 10-1 cm2V-1s-1. PIDTOBT had the highestelectron mobility of 0.18 cm2V-1s-1 after annealing at 200 °C. From the small molecule and polymerresults, it is clear that IDTO is a promising material for unipolar n-type organic semiconductors. SinceIDTO has a strong electron accepting feature, it was thought that IDTO would have another use as anelectron trap. By blending IDTO with an ambipolar polymer that has a LUMO energy level abovethat of IDTO; electron transport could be suppressed under the correct conditions. The three smallmolecule IDTO compounds were blended with PINDFBT (TT) and PINDFBT (HH) to investigate theelectron trapping ability of IDTO. Complete suppression of electron transport was not observed butthe overall trend agreed with the theory. 6-bromo-IDTO having the lowest LUMO energy levelshowed the strongest electron trapping effect while IDTO had the weakest effect due to its higherLUMO energy level. This thesis provides a comprehensive study of the development and applicationof the novel material, IDTO.