Polyfluorenes as Organic Semiconductors for Polymeric Field Effect Transistors

Abstract

Polyfluorenes are a class of polyaromatic macromolecules that are characterized by an alternating backbone structure that consists of a 9,9-dialkylfluorene unit in combination with another aromatic group. The nature of this aromatic unit plays a key role in the electronic properties of the polymers. For example, polyfluorenes which combine chromophoric and charge transporting aromatic units have received a great deal of attention over the last several years as the emissive layer in polymeric light emitting diodes [LUMATION* Light-Emitting Polymers (LEPs)]. More recently, polyfluorenes have also been designed to perform as the organic semiconducting layer in polymeric field effect transistors (PFETs). This effort has led to a class of polymeric semiconductors with an excellent combination of charge mobility, environmental stability, and processability. One such polymer is the polyfluorene based on an alternating backbone of 9,9-dioctylfluorene and 2,2'-bithiophene units. This material has been shown to have charge mobilities as high as 0.02 cm2/V-s with current on/off ratios of up to 106. The poly(fluorene-bithiophene) is more resistant to doping by atmospheric oxygen than other polymeric semiconductors such as poly(3-hexylthiophene). Inks based on solutions of poly(fluorene-bithiophene) in xylene, mesitylene, and other solvents have also been prepared. The paper will focus on the recent advances in the synthesis, fabrication, and electrical characterization of poly(fluorene-bithiophene). *Trademark of The Dow Chemical Company

Synthesis, Characterization, and Transistor Response of Semiconducting Silole Polymers with Substantial Hole Mobility and Air Stability. Experiment and Theory

“…Both the melting and recrystallization peaks are completely reversible over four cycles. The DSC of polymer 12 exhibits two endotherms at 259 and 277 °C and one exotherm at 196 °C upon cooling, consistent with a previous report …”

“…The DSC of polymer 12 exhibits two endotherms at 259 and 277 °C and one exotherm at 196 °C upon cooling, consistent with a previous report. 76 On average, the polymers containing bithiophene units have higher melting temperatures, suggesting closer packing in the solid state. The melting temperatures of pair 6 and 9 and pair 7 and 10 are rather comparable.…”

Field-Induced Stimulated Emission in a Polymer–Liquid Crystal Mixture

“…Both these devices employ, as light-absorbing materials, conjugated polymers (CPs). CPs are organic semiconductors that have gained wide popularity in photonics due to their appealing properties: they display a combination of broad band emission, high optical gain, versatility in processing, they are ductile and can be electrically pumped (so far in LEDs). , Indeed many optoelectronic devices based on CPs have been demonstrated such as solar cells, , phototransistors, , photodetectors, , optically pumped lasers − and organic light emitting diodes (OLEDs). , …”