New blue light emitting cyanopyridine based conjugated polymers: From molecular engineering to PLED applications

Abstract

In this work, we report the design of three new cyanopyridine scaffold based polymers, viz. TPy <inf>1-3</inf> as potential blue light emitters for PLED applications. The new polymer design comprise, a cyanopyridine core as an electron accepting entity, thiophene as an electron donating unit with different auxiliary donors, viz. phenylene (TPy <inf>1</inf> ), biphenyl (TPy <inf>2</inf> ), and fluorene (TPy <inf>3</inf> ), and have been synthesized, following standard synthetic protocols including Suzuki-cross coupling polymerization reaction. Further, in order to assess all the prerequisites to act as an active emitter, the polymers TPy <inf>1-3,</inf> were subjected to structural, thermal, linear optical, electrochemical and computational studies. The results revealed that, all the polymers were thermally stable up to 300 ?C and their estimated optical band-gaps were found to be 2.59–2.80 eV. Finally, new polymer light emitting diode (PLED) were fabricated by employing the polymers TPy <inf>1-3,</inf> as active emissive material with a configuration of ITO/PEDOT: PSS/Polymer/Al. Interestingly, all the fabricated devices, exhibited an intense blue electroluminescence at 12 V with low threshold voltages of 4.2–4.8 V, signifying an effective injection of electron in the device. © 2019 Elsevier B.V.