Design of a D–Di–π–A Architecture with Different Auxiliary Donors for Dye‐Sensitized Solar Cells: Density Functional Theory/Time‐Dependent‐Density Functional Theory Study of the Effect of Secondary Donors

Abstract

Abstract In this work, five novel D–D i –π–A molecules based on ethoxy donor moiety are designed from the reference molecule R to optimize the photovoltaic performance of dye‐sensitized solar cell (DSSC) systems. The geometrical, electronic, optical, and photovoltaic characteristics of the D1–D5 compounds are analyzed. D1–D5 show band gaps ( E gap ) in the range of 2.13–2.25 eV with the maximum absorption wavelength ( λ abs ) in 427–451 nm. Charge transport characteristics are examined by employing frontier molecular orbitals and density of states. The transition density matrix is employed to predict the characteristics of the electronic excitation mechanisms and the localization of the electronic holes betwixt the donor and acceptor moieties. The data obtained indicate that adding the various auxiliary donors to dye (R) facilitate its electron injection and improve the impact of intramolecular charge‐transfer (ICT), which lead to a red‐shifted absorption. The open‐circuit voltage ( V oc ) data obtained from theoretical computations vary from 1.26 to 1.30 eV, while the data for the light harvesting efficiency range from 0.97 to 1.00. Indeed, this study may help chemists to synthesize efficient dyes for DSSC.