The influence of the structural variations in the π-bridge of D-π-A organic dyes on the efficiency of dye-sensitized solar cells (DSSCs): A DFT computational study

In this study, four donor-$\pi$-acceptor dyes based on on benzocarbazole as donor have been designed by varying the bridge groups. Their optoelectronic and photovoltaic properties have been evaluated using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. Several key parameters have been investigated to reveal the influence of the modulation of the spacer group in improving light-absorbing capacities and enhancing the intramolecular charge transfer. From the results indicated that the molecule Dye-c show the best performance among the designed dyes, showing low-lying HOMO energy level (-5.29 eV), small energy gap (2.47 eV), a maximum wavelength of 446 nm. This contribution can provide an efficient guidance for the design of efficient D-$\pi$-A dyes for dye-sensitized solar cells (DSSCs).