Influence of donor and acceptor moieties on photophysical properties of N-naphthylcarbazole based conjugated terpolymers

Abstract

In this context, two novels random terpolymers DFC (D1-A-D2-A) and EFC (D1-D0-D2-D0) based on N-naphthylcarbazole were synthesized with good yield via C–H arylation technique. By adding DPP- an acceptor in terpolymer backbone absorption range, energy levels and photophysical property can be efficiently tuned. The molecular design and integrities of the terpolymers were studied by DFT calculation and the bandgap results were confirmed from cyclic voltammetry and UV–Vis spectroscopy. The synthesized N-naphthylcarbazole based terpolymers showed good thermal stability and solubility which is suitable for the manufacturing of devices. The optical characterization showed that the addition of an electron accepting unit wide the absorption range i.e up to 800 nm in DFC (a redshift of 235 nm to EFC) and narrowed the energy band gap, a strategic concern to increase the efficiency of photovoltaic devices. With complementary absorption, favourable internal morphology and compact molecular packing, from AFM and XRD, DFC as barrier layer in DSSC showed the highest power conversion efficiency of 4.07% and 3.49% with high short circuit current density (Jsc) with both Pt and PEDOT: PSS counter electrodes.