We herein report the design and synthesis of three new indole and carbazole based dyes (D1, D2 and D3) with a donor-(π-spacer)-acceptor (D-π-A) configuration with N-methylindole and carbazole as donors, barbituric acid and N-acyloxindole as acceptors/anchoring groups. DFT calculations of three dyes D1, D2 and D3 by using the B3LYP/6-31+G(d) basis set provided the optimized ground-state molecular geometries. Theoretical light harvesting efficiencies (LHE), of all the dyes were studied by time dependent density functional theory (TD-DFT) method in order to shed the light on how the π-conjugation order influence the performance of the dyes. Along with the TD-DFT calculations photophysical and electrochemical properties of the dyes were investigated by UV spectroscopy and cyclic voltammetry (CV), which indicates that D3 could show the best performance among the three dyes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim