Growth of thiophene based oligomers using Stille and direct arylation methods for optoelectronic applications

Abstract

Palladium catalyzed Stille coupling reactions are extensively used for the preparation of functionalised thiophene based polymers. In addition, polycondensation via direct C-H arylation produces alternating copolymers in moderate yields. In the present work, we report the synthesis and optoelectronic properties of thiophene based compounds having rigid cycloalkanone and a novel hexhydro-2H-indazole spacers in between. X-ray diffraction analysis shows the semi-crystalline nature of the synthesized materials with extensive side chain crystallinity. Band-gap energy of the synthesized materials has been obtained experimentally via optical and electrochemical methods and theoretically via computational studies. Open aperture Z-Scan results confirm the competence of these materials as optical limiters (NLO) while the photoluminescence emission characteristics and Schottky diode characteristics indicate their application prospects in Polymer Light Emitting Diodes (PLEDs). Polymers having hexhydro-2H-indazole spacers appear to be promising candidates for optoelectronic applications.