New Organic Semiconductors Based on Polytriarylamines

Dr. Mario Hoyos in collaboration with several universities in the UK, has recently published a paper on the influence of the extended conjugation in poly(triarylamine)s in the performance of field effect transistors (OFETs).

Poly(triarylamine)s are an important class of amorphous semiconducting polymers exhibiting high performance for extended periods of time outdoors. This environmental stability, coupled with its amorphous solid structure, are highly desirable characteristics for use in chemical sensors, allowing a simple and reproducible processing into thin films as compared to more complex processes required for semicrystalline polymers. Poly(triarylamine)s are also used as conductive materials in photocopiers, laser printers, organic emitting diodes (OLEDs), indicative RFID radio frequency type, chemical vapor sensors, electroluminescent devices, as cathode components and electroactive separator material in batteries rechargeable lithium.

Poly(triarylamine)s with extended fused backbones are accessible by the coupling of anilines with dibromoarenes based on substituted indenofluorenes, diindenofluorenes, carbazoles and indolocarbazoles. The optical and electrochemical properties of these polymers show an increase in the HOMO energy levels and the onset of absorption on extending the length of the fused ring segment. The polymer derived from the indenofluorene unit shows the highest reported performance for a polytriarylamine in an OFET and this observation can be rationalized by DFT calculations of model oligomers that show higher calculated reorganization energies for the more extended diindenofluorene units.