Studies on photophysical and electrochemical properties of triphenylamine α, β-unsaturated ketone side-arm PAE CPs

Abstract

A series of polyaryleneethynylene (PAE) conjugated polymers (CPs) have been synthesized using 1-(4-((2,5-diethynylphenyl)ethynyl)phenyl)-3-(4-(diphenylamino)phenyl)prop-2-en-1-one, 1,4-diiodo-2,5-bis(octyloxy)benzene, 1,4-bis(dodecyloxy)-2,5-diiodobenzene and 2,7-diiodo-9,9′-dioctyl-9H-fluorene with terminal hydrogen presented diethynylene and diiodo–substituted precursor as acceptor and donor monomers. The donor and acceptor (D-A) unit network of CPs developed through the Heck–Sonogashira cross-coupling reaction mechanism. The triphenylamine attached α,β unsaturated ketone of phenylethynylene side-arm PAE CPs was studied for their photophysical and electrochemical behaviors based on the molecular-level electronic properties. From the solution-phase UV–visible (UV–Vis) and Fluorescence (FL) measurements explained the π–π* electronic transition and intramolecular charge transfer (ICT) behavior of the CPs. The shift between UV–Vis maxima and FL maxima are well accounted for calculating the Stokes shift, which supports the evidence for the red shift of PAE CPs, namely NPAEC8-127 nm, NPAEC12-131 nm, and NPAEF8-25 nm. The thin-film UV–Vis absorption spectra and electrochemical measurements ascertain the existence of the optical low band gap (Eg) (NPAEC8-2.57 nm, NPAEC12-2.62 nm, and NPAEF8-2.70 nm) and HOMO–LUMO energy levels of the PAE CPs. Based on data obtained from different studies, it is suggested that the synthesized PAE CPs are suitable for the photovoltaic and sensor applications.