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 BTA(1), BTA(2), BTA(3) and BTA(4) 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-gamma CF3. BTA(3) and BTA(4) 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 acceptor moieties have been found nearly identical, indicating that electron density is distributed over the whole molecule for all designed molecules. BTA(3) has minimum electron mobility 0.0086897 eV that makes it a good candidate for efficient solar cell. Binding energy (E-b) of BTA(1), BTA(2) and BTA(4) is less than that of BTIC-2Cl-gamma CF3 indicating greater dissociation of excitons. BTA(4) 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 efficient organic solar cell (OSC) devices.