Quantum chemical simulations of benzothiadiazole (BT) based small molecule donor materials for efficient organic solar cells

Abstract

Four new donor molecules based on benzothiadiazole (BT) core namely BTA1, BTA2, BTA3 and BTA4 have been designed with A-D-A configuration. Quantum chemical simulations represent that these molecules show the best optoelectronic properties just like model compound BTIC-2Cl-γCF3. BTA3 and BTA4 showed the red shifted absorption value (685 nm and 633 nm) respectively as well as lowest band gap 2.31 eV and 2.27 eV respectively. The findings of DOS and FMO for modified acceptormoieties have been found nearly identical, indicating that electron density is distributed over the whole molecule for all designed molecules. BTA3 has minimum electron mobility 0.0086897 eV that makes it a good candidate for efficient solar cell. Binding energy (Eb) of BTA1, BTA2 and BTA4 is less than that of BTIC-2Cl-γCF3 indicating greater dissociation of excitons. BTA4 has the highest dipole moment among all molecules. As a result, this would be the best molecule for fabricating solar cell sheets. These four newly designed A-D-A donor molecules are therefore proposed as appropriate donor materials for highly efficientorganic solar cell (OSC) devices.